Adds Water Vapor and the Electrolyzer (#30875)

* this will work first try (adds water vapor and the electrolyzer)

* naming fix

* removes a warn

* makes water vapor able to be seen and adds it to the tiny_test atmos map

* Build Rust library

* adds the electrolyzer to all maps, and linter fix

* linter fix part 2

* electrolyzer tweak and more work on the test_atmos map

* tgui rebuilding

* re
rebuilding tgui

* makes the electrolyzer consume power and some small test atmos touch ups

* im axing the test_tiny because i don't want to map it

* clarifies how much power the electrolyzer uses

* Build Rust library

* suggestionss

Co-authored-by: DGamerL <108773801+DGamerL@users.noreply.github.com>
Co-authored-by: JimKil3 <47290811+JimKil3@users.noreply.github.com>
Signed-off-by: Hayden Redacted <91229275+haydenredacted@users.noreply.github.com>

* updating the SM manual

* electrolyzer tweaks

* dg suggestions pt. 2

Co-authored-by: DGamerL <108773801+DGamerL@users.noreply.github.com>
Signed-off-by: Hayden Redacted <91229275+haydenredacted@users.noreply.github.com>

* removed unused code

---------

Signed-off-by: Hayden Redacted <91229275+haydenredacted@users.noreply.github.com>
Co-authored-by: paradisess13[bot] <165046124+paradisess13[bot]@users.noreply.github.com>
Co-authored-by: warriorstar-orion <orion@snowfrost.garden>
Co-authored-by: DGamerL <108773801+DGamerL@users.noreply.github.com>
Co-authored-by: JimKil3 <47290811+JimKil3@users.noreply.github.com>

code/modules/admin/verbs/diagnostics.dm

@@ -15,7 +15,7 @@
 		if(T.active_hotspot)
 			burning = 1
 
-	to_chat(usr, "<span class='notice'>@[target.x],[target.y]: O:[GM.oxygen()] T:[GM.toxins()] N:[GM.nitrogen()] C:[GM.carbon_dioxide()] N2O: [GM.sleeping_agent()] Agent B: [GM.agent_b()] Hydrogen: [GM.hydrogen()] w [GM.temperature()] Kelvin, [GM.return_pressure()] kPa [(burning)?("<span class='warning'>BURNING</span>"):(null)]</span>")
+	to_chat(usr, "<span class='notice'>@[target.x],[target.y]: O:[GM.oxygen()] T:[GM.toxins()] N:[GM.nitrogen()] C:[GM.carbon_dioxide()] N2O: [GM.sleeping_agent()] Agent B: [GM.agent_b()] Hydrogen: [GM.hydrogen()] Water Vapor: [GM.water_vapor()] w [GM.temperature()] Kelvin, [GM.return_pressure()] kPa [(burning)?("<span class='warning'>BURNING</span>"):(null)]</span>")
 
 	message_admins("[key_name_admin(usr)] has checked the air status of [target]")
 	log_admin("[key_name(usr)] has checked the air status of [target]")

code/modules/atmospherics/environmental/LINDA_system.dm

@@ -147,4 +147,7 @@
 	if(flag & LINDA_SPAWN_HYDROGEN)
 		G.set_hydrogen(G.hydrogen() + amount)
 
+	if(flag & LINDA_SPAWN_WATER_VAPOR)
+		G.set_water_vapor(G.water_vapor() + amount)
+
 	blind_release_air(G)

code/modules/atmospherics/environmental/LINDA_turf_tile.dm

@@ -13,6 +13,7 @@
 		air.set_sleeping_agent(sleeping_agent)
 		air.set_agent_b(agent_b)
 		air.set_hydrogen(hydrogen)
+		air.set_water_vapor(water_vapor)
 		air.set_temperature(temperature)
 	else
 		air.set_oxygen(0)
@@ -22,6 +23,7 @@
 		air.set_sleeping_agent(0)
 		air.set_agent_b(0)
 		air.set_hydrogen(0)
+		air.set_water_vapor(0)
 		air.set_temperature(0)
 	return air
 
@@ -74,6 +76,8 @@
 			return GLOB.plmaster
 		if("sleeping_agent")
 			return GLOB.slmaster
+		if("water_vapor")
+			return GLOB.wvmaster
 	return null
 
 /turf/simulated/proc/tile_graphic(datum/gas_mixture/air)
@@ -86,6 +90,9 @@
 
 	if(air.sleeping_agent() > 1)
 		return "sleeping_agent"
+
+	if(air.water_vapor() > MOLES_WATER_VAPOR_VISIBLE)
+		return "water_vapor"
 	return null
 
 /turf/proc/high_pressure_movements(flow_x, flow_y)
@@ -180,7 +187,7 @@
 /turf/proc/Initialize_Atmos(milla_tick)
 	// This is one of two places expected to call this otherwise-unsafe method.
 	var/list/connectivity = private_unsafe_recalculate_atmos_connectivity()
-	var/list/air = list(oxygen, carbon_dioxide, nitrogen, toxins, sleeping_agent, agent_b, hydrogen, temperature)
+	var/list/air = list(oxygen, carbon_dioxide, nitrogen, toxins, sleeping_agent, agent_b, hydrogen, water_vapor, temperature)
 	milla_data = connectivity[1] + list(atmos_mode, SSmapping.environments[atmos_environment]) +  air + connectivity[2]
 
 /turf/simulated/Initialize_Atmos(milla_tick)

code/modules/atmospherics/gasmixtures/gas_mixture.dm

@@ -9,14 +9,16 @@ What are the archived variables for?
 #define SPECIFIC_HEAT_N2O		40
 #define SPECIFIC_HEAT_AGENT_B	300
 #define SPECIFIC_HEAT_HYDROGEN  15
+#define SPECIFIC_HEAT_WATER_VAPOR  33
 
-#define HEAT_CAPACITY_CALCULATION(oxygen, carbon_dioxide, nitrogen, toxins, sleeping_agent, agent_b, hydrogen, innate_heat_capacity) \
+#define HEAT_CAPACITY_CALCULATION(oxygen, carbon_dioxide, nitrogen, toxins, sleeping_agent, agent_b, hydrogen, water_vapor, innate_heat_capacity) \
 	(carbon_dioxide * SPECIFIC_HEAT_CDO + \
 	(oxygen + nitrogen) * SPECIFIC_HEAT_AIR + \
 	toxins * SPECIFIC_HEAT_TOXIN + \
 	sleeping_agent * SPECIFIC_HEAT_N2O + \
 	agent_b * SPECIFIC_HEAT_AGENT_B + \
 	hydrogen * SPECIFIC_HEAT_HYDROGEN + \
+	water_vapor * SPECIFIC_HEAT_WATER_VAPOR + \
 	innate_heat_capacity)
 
 #define MINIMUM_HEAT_CAPACITY	0.0003
@@ -40,6 +42,7 @@ What are the archived variables for?
 	var/private_sleeping_agent = 0
 	var/private_agent_b = 0
 	var/private_hydrogen = 0
+	var/private_water_vapor = 0
 	var/private_temperature = 0 //in Kelvin
 	var/private_hotspot_temperature = 0
 	var/private_hotspot_volume = 0
@@ -54,6 +57,7 @@ What are the archived variables for?
 	var/private_sleeping_agent_archived = 0
 	var/private_agent_b_archived = 0
 	var/private_hydrogen_archived = 0
+	var/private_water_vapor_archived = 0
 	var/private_temperature_archived = 0
 
 	/// Is this mixture currently synchronized with MILLA? Always true for non-bound mixtures.
@@ -140,6 +144,17 @@ What are the archived variables for?
 		stack_trace("Out-of-bounds value [value] clamped to [clamped].")
 	private_hydrogen = clamped
 
+/datum/gas_mixture/proc/water_vapor()
+	return private_water_vapor
+
+/datum/gas_mixture/proc/set_water_vapor(value)
+	if(isnan(value) || !isnum(value))
+		CRASH("Bad value: [value]")
+	var/clamped = clamp(value, 0, 1e10)
+	if(value != clamped)
+		stack_trace("Out-of-bounds value [value] clamped to [clamped].")
+	private_water_vapor = clamped
+
 
 /datum/gas_mixture/proc/temperature()
 	return private_temperature
@@ -163,14 +178,14 @@ What are the archived variables for?
 
 	///joules per kelvin
 /datum/gas_mixture/proc/heat_capacity()
-	return HEAT_CAPACITY_CALCULATION(private_oxygen, private_carbon_dioxide, private_nitrogen, private_toxins, private_sleeping_agent, private_agent_b, private_hydrogen, innate_heat_capacity)
+	return HEAT_CAPACITY_CALCULATION(private_oxygen, private_carbon_dioxide, private_nitrogen, private_toxins, private_sleeping_agent, private_agent_b, private_hydrogen, private_water_vapor, innate_heat_capacity)
 
 /datum/gas_mixture/proc/heat_capacity_archived()
-	return HEAT_CAPACITY_CALCULATION(private_oxygen_archived, private_carbon_dioxide_archived, private_nitrogen_archived, private_toxins_archived, private_sleeping_agent_archived, private_agent_b_archived, private_hydrogen_archived, innate_heat_capacity)
+	return HEAT_CAPACITY_CALCULATION(private_oxygen_archived, private_carbon_dioxide_archived, private_nitrogen_archived, private_toxins_archived, private_sleeping_agent_archived, private_agent_b_archived, private_hydrogen_archived, private_water_vapor_archived, innate_heat_capacity)
 
 	/// Calculate moles
 /datum/gas_mixture/proc/total_moles()
-	return private_oxygen + private_carbon_dioxide + private_nitrogen + private_toxins + private_sleeping_agent + private_agent_b + private_hydrogen
+	return private_oxygen + private_carbon_dioxide + private_nitrogen + private_toxins + private_sleeping_agent + private_agent_b + private_hydrogen + private_water_vapor
 
 /datum/gas_mixture/proc/total_trace_moles()
 	return private_agent_b
@@ -198,6 +213,7 @@ What are the archived variables for?
 	private_sleeping_agent_archived = private_sleeping_agent
 	private_agent_b_archived = private_agent_b
 	private_hydrogen_archived = private_hydrogen
+	private_water_vapor_archived = private_water_vapor
 
 	private_temperature_archived = private_temperature
 
@@ -223,6 +239,7 @@ What are the archived variables for?
 	private_sleeping_agent += giver.private_sleeping_agent
 	private_agent_b += giver.private_agent_b
 	private_hydrogen += giver.private_hydrogen
+	private_water_vapor += giver.private_water_vapor
 
 	set_dirty()
 	return TRUE
@@ -252,6 +269,7 @@ What are the archived variables for?
 	removed.private_sleeping_agent = QUANTIZE((private_sleeping_agent / sum) * amount)
 	removed.private_agent_b = QUANTIZE((private_agent_b / sum) * amount)
 	removed.private_hydrogen = QUANTIZE((private_hydrogen / sum) * amount)
+	removed.private_water_vapor = QUANTIZE((private_water_vapor / sum) * amount)
 
 	private_oxygen = max(private_oxygen - removed.private_oxygen, 0)
 	private_nitrogen = max(private_nitrogen - removed.private_nitrogen, 0)
@@ -260,6 +278,7 @@ What are the archived variables for?
 	private_sleeping_agent = max(private_sleeping_agent - removed.private_sleeping_agent, 0)
 	private_agent_b = max(private_agent_b - removed.private_agent_b, 0)
 	private_hydrogen = max(private_hydrogen - removed.private_hydrogen, 0)
+	private_water_vapor = max(private_water_vapor - removed.private_water_vapor, 0)
 
 	removed.private_temperature = private_temperature
 
@@ -284,6 +303,7 @@ What are the archived variables for?
 	removed.private_sleeping_agent = QUANTIZE(private_sleeping_agent * ratio)
 	removed.private_agent_b = QUANTIZE(private_agent_b * ratio)
 	removed.private_hydrogen = QUANTIZE(private_hydrogen * ratio)
+	removed.private_water_vapor = QUANTIZE(private_water_vapor * ratio)
 
 	private_oxygen = max(private_oxygen - removed.private_oxygen, 0)
 	private_nitrogen = max(private_nitrogen - removed.private_nitrogen, 0)
@@ -292,6 +312,7 @@ What are the archived variables for?
 	private_sleeping_agent = max(private_sleeping_agent - removed.private_sleeping_agent, 0)
 	private_agent_b = max(private_agent_b - removed.private_agent_b, 0)
 	private_hydrogen = max(private_hydrogen - removed.private_hydrogen, 0)
+	private_water_vapor = max(private_water_vapor - removed.private_water_vapor, 0)
 
 	removed.private_temperature = private_temperature
 	set_dirty()
@@ -307,6 +328,7 @@ What are the archived variables for?
 	private_sleeping_agent = sample.private_sleeping_agent
 	private_agent_b = sample.private_agent_b
 	private_hydrogen = sample.private_hydrogen
+	private_water_vapor = sample.private_water_vapor
 
 	private_temperature = sample.private_temperature
 	set_dirty()
@@ -323,6 +345,7 @@ What are the archived variables for?
 	private_sleeping_agent = model.sleeping_agent
 	private_agent_b = model.agent_b
 	private_hydrogen = model.hydrogen
+	private_water_vapor = model.water_vapor
 
 	//acounts for changes in temperature
 	var/turf/model_parent = model.parent_type
@@ -348,6 +371,7 @@ What are the archived variables for?
 	var/delta_sleeping_agent = QUANTIZE(private_sleeping_agent_archived - sharer.private_sleeping_agent_archived) / (atmos_adjacent_turfs + 1)
 	var/delta_agent_b = QUANTIZE(private_agent_b_archived - sharer.private_agent_b_archived) / (atmos_adjacent_turfs + 1)
 	var/delta_hydrogen = QUANTIZE(private_hydrogen_archived - sharer.private_hydrogen_archived) / (atmos_adjacent_turfs + 1)
+	var/delta_water_vapor = QUANTIZE(private_water_vapor_archived - sharer.private_water_vapor_archived) / (atmos_adjacent_turfs + 1)
 
 	var/delta_temperature = (private_temperature_archived - sharer.private_temperature_archived)
 
@@ -402,6 +426,13 @@ What are the archived variables for?
 			else
 				heat_capacity_sharer_to_self -= hydrogen_heat_capacity
 
+		if(delta_water_vapor)
+			var/water_vapor_heat_capacity = SPECIFIC_HEAT_WATER_VAPOR * delta_water_vapor
+			if(delta_water_vapor > 0)
+				heat_capacity_self_to_sharer += water_vapor_heat_capacity
+			else
+				heat_capacity_sharer_to_self -= water_vapor_heat_capacity
+
 		old_self_heat_capacity = heat_capacity()
 		old_sharer_heat_capacity = sharer.heat_capacity()
 
@@ -426,7 +457,10 @@ What are the archived variables for?
 	private_hydrogen -= delta_hydrogen
 	sharer.private_hydrogen += delta_hydrogen
 
-	var/moved_moles = (delta_oxygen + delta_carbon_dioxide + delta_nitrogen + delta_toxins + delta_sleeping_agent + delta_agent_b + delta_hydrogen)
+	private_water_vapor -= delta_water_vapor
+	sharer.private_water_vapor += delta_water_vapor
+
+	var/moved_moles = (delta_oxygen + delta_carbon_dioxide + delta_nitrogen + delta_toxins + delta_sleeping_agent + delta_agent_b + delta_hydrogen + delta_water_vapor)
 
 	if(abs(delta_temperature) > MINIMUM_TEMPERATURE_DELTA_TO_CONSIDER)
 		var/new_self_heat_capacity = old_self_heat_capacity + heat_capacity_sharer_to_self - heat_capacity_self_to_sharer
@@ -457,6 +491,7 @@ What are the archived variables for?
 	var/delta_sleeping_agent = QUANTIZE(private_sleeping_agent_archived - model.sleeping_agent) / (atmos_adjacent_turfs + 1)
 	var/delta_agent_b = QUANTIZE(private_agent_b_archived - model.agent_b) / (atmos_adjacent_turfs + 1)
 	var/delta_hydrogen = QUANTIZE(private_hydrogen_archived - model.hydrogen) / (atmos_adjacent_turfs + 1)
+	var/delta_water_vapor = QUANTIZE(private_water_vapor_archived - model.water_vapor) / (atmos_adjacent_turfs + 1)
 
 	var/delta_temperature = (private_temperature_archived - model.temperature)
 
@@ -497,6 +532,11 @@ What are the archived variables for?
 			heat_transferred -= hydrogen_heat_capacity * model.temperature
 			heat_capacity_transferred -= hydrogen_heat_capacity
 
+		if(delta_water_vapor)
+			var/water_vapor_heat_capacity = SPECIFIC_HEAT_WATER_VAPOR * delta_water_vapor
+			heat_transferred -= water_vapor_heat_capacity * model.temperature
+			heat_capacity_transferred -= water_vapor_heat_capacity
+
 		old_self_heat_capacity = heat_capacity()
 
 	private_oxygen -= delta_oxygen
@@ -506,8 +546,9 @@ What are the archived variables for?
 	private_sleeping_agent -= delta_sleeping_agent
 	private_agent_b -= delta_agent_b
 	private_hydrogen -= delta_hydrogen
+	private_water_vapor -= delta_water_vapor
 
-	var/moved_moles = (delta_oxygen + delta_carbon_dioxide + delta_nitrogen + delta_toxins + delta_sleeping_agent + delta_agent_b + delta_hydrogen)
+	var/moved_moles = (delta_oxygen + delta_carbon_dioxide + delta_nitrogen + delta_toxins + delta_sleeping_agent + delta_agent_b + delta_hydrogen + delta_water_vapor)
 
 	if(abs(delta_temperature) > MINIMUM_TEMPERATURE_DELTA_TO_CONSIDER)
 		var/new_self_heat_capacity = old_self_heat_capacity - heat_capacity_transferred
@@ -518,7 +559,7 @@ What are the archived variables for?
 
 	set_dirty()
 	if((delta_temperature > MINIMUM_TEMPERATURE_TO_MOVE) || abs(moved_moles) > MINIMUM_MOLES_DELTA_TO_MOVE)
-		var/delta_pressure = private_temperature_archived * (total_moles() + moved_moles) - model.temperature * (model.oxygen + model.carbon_dioxide + model.nitrogen + model.toxins + model.sleeping_agent + model.agent_b + model.hydrogen)
+		var/delta_pressure = private_temperature_archived * (total_moles() + moved_moles) - model.temperature * (model.oxygen + model.carbon_dioxide + model.nitrogen + model.toxins + model.sleeping_agent + model.agent_b + model.hydrogen + model.water_vapor)
 		return delta_pressure * R_IDEAL_GAS_EQUATION / volume
 	else
 		return 0
@@ -532,6 +573,7 @@ What are the archived variables for?
 	var/delta_sleeping_agent = (private_sleeping_agent_archived - model.sleeping_agent) / (atmos_adjacent_turfs + 1)
 	var/delta_agent_b = (private_agent_b_archived - model.agent_b) / (atmos_adjacent_turfs + 1)
 	var/delta_hydrogen = (private_hydrogen_archived - model.hydrogen) / (atmos_adjacent_turfs + 1)
+	var/delta_water_vapor = (private_water_vapor_archived - model.water_vapor) / (atmos_adjacent_turfs + 1)
 
 	var/delta_temperature = (private_temperature_archived - model.temperature)
 
@@ -541,7 +583,8 @@ What are the archived variables for?
 		|| ((abs(delta_toxins) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_toxins) >= private_toxins_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
 		|| ((abs(delta_sleeping_agent) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_sleeping_agent) >= private_sleeping_agent_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
 		|| ((abs(delta_agent_b) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_agent_b) >= private_agent_b_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
-		|| ((abs(delta_hydrogen) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_hydrogen) >= private_hydrogen_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)))
+		|| ((abs(delta_hydrogen) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_hydrogen) >= private_hydrogen_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
+		|| ((abs(delta_water_vapor) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_water_vapor) >= private_water_vapor_archived * MINIMUM_AIR_RATIO_TO_SUSPEND)))
 		return FALSE
 	if(abs(delta_temperature) > MINIMUM_TEMPERATURE_DELTA_TO_SUSPEND)
 		return FALSE
@@ -613,6 +656,9 @@ What are the archived variables for?
 	if((abs(private_hydrogen - sample.private_hydrogen) > MINIMUM_AIR_TO_SUSPEND) && \
 		((private_hydrogen < (1 - MINIMUM_AIR_RATIO_TO_SUSPEND) * sample.private_hydrogen) || (private_hydrogen > (1 + MINIMUM_AIR_RATIO_TO_SUSPEND) * sample.private_hydrogen)))
 		return FALSE
+	if((abs(private_water_vapor - sample.private_water_vapor) > MINIMUM_AIR_TO_SUSPEND) && \
+		((private_water_vapor < (1 - MINIMUM_AIR_RATIO_TO_SUSPEND) * sample.private_water_vapor) || (private_water_vapor > (1 + MINIMUM_AIR_RATIO_TO_SUSPEND) * sample.private_water_vapor)))
+		return FALSE
 
 	if(total_moles() > MINIMUM_AIR_TO_SUSPEND)
 		if((abs(private_temperature - sample.private_temperature) > MINIMUM_TEMPERATURE_DELTA_TO_SUSPEND) && \
@@ -628,6 +674,7 @@ What are the archived variables for?
 	var/delta_sleeping_agent = (private_sleeping_agent - model.sleeping_agent)
 	var/delta_agent_b = (private_agent_b - model.agent_b)
 	var/delta_hydrogen = (private_hydrogen - model.hydrogen)
+	var/delta_water_vapor = (private_water_vapor - model.water_vapor)
 
 	var/delta_temperature = (private_temperature - model.temperature)
 
@@ -637,7 +684,8 @@ What are the archived variables for?
 		|| ((abs(delta_toxins) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_toxins) >= private_toxins * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
 		|| ((abs(delta_sleeping_agent) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_sleeping_agent) >= private_sleeping_agent * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
 		|| ((abs(delta_agent_b) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_agent_b) >= private_agent_b * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
-		|| ((abs(delta_hydrogen) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_hydrogen) >= private_hydrogen * MINIMUM_AIR_RATIO_TO_SUSPEND)))
+		|| ((abs(delta_hydrogen) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_hydrogen) >= private_hydrogen * MINIMUM_AIR_RATIO_TO_SUSPEND)) \
+		|| ((abs(delta_water_vapor) > MINIMUM_AIR_TO_SUSPEND) && (abs(delta_water_vapor) >= private_water_vapor * MINIMUM_AIR_RATIO_TO_SUSPEND)))
 		return FALSE
 	if(abs(delta_temperature) > MINIMUM_TEMPERATURE_DELTA_TO_SUSPEND)
 		return FALSE
@@ -729,7 +777,7 @@ What are the archived variables for?
 		// Burn a portion of our hydrogen equal to reaction_rate, but no more than we have or have oxygen for.
 		var/burned_hydrogen = min(reaction_rate * private_hydrogen, private_hydrogen, private_oxygen * 2)
 		var/burned_oxygen = min(burned_hydrogen / 2, private_oxygen)
-		// var/produced_water_vapor = (burned_hydrogen / H2_NEEDED_FOR_H2O)
+		var/produced_water_vapor = (burned_hydrogen / H2_NEEDED_FOR_H2O)
 
 
 		var/old_heat_capacity = heat_capacity()
@@ -737,7 +785,7 @@ What are the archived variables for?
 		// Burn gasses
 		private_hydrogen -= burned_hydrogen
 		private_oxygen -= burned_oxygen
-		// private_water_vapor += produced_water_vapor
+		private_water_vapor += produced_water_vapor
 
 		// Calculate gained energy
 		var/energy_released = HYDROGEN_BURN_ENERGY * burned_hydrogen
@@ -774,6 +822,7 @@ What are the archived variables for?
 	private_sleeping_agent = milla[MILLA_INDEX_SLEEPING_AGENT]
 	private_agent_b = milla[MILLA_INDEX_AGENT_B]
 	private_hydrogen = milla[MILLA_INDEX_HYDROGEN]
+	private_water_vapor = milla[MILLA_INDEX_WATER_VAPOR]
 	innate_heat_capacity = milla[MILLA_INDEX_INNATE_HEAT_CAPACITY]
 	private_temperature = milla[MILLA_INDEX_TEMPERATURE]
 	private_hotspot_temperature = milla[MILLA_INDEX_HOTSPOT_TEMPERATURE]
@@ -789,6 +838,7 @@ What are the archived variables for?
 	var/total_sleeping_agent = 0
 	var/total_agent_b = 0
 	var/total_hydrogen = 0
+	var/total_water_vapor = 0
 	var/must_share = FALSE
 
 	// Collect all the cheap data and check if there's a significant temperature difference.
@@ -810,11 +860,12 @@ What are the archived variables for?
 		total_sleeping_agent += G.private_sleeping_agent
 		total_agent_b += G.private_agent_b
 		total_hydrogen += G.private_hydrogen
+		total_water_vapor += G.private_water_vapor
 
 	if(total_volume == 0)
 		return
 
-	if(total_volume < 0 || isnan(total_volume) || !isnum(total_volume) || total_oxygen < 0 || isnan(total_oxygen) || !isnum(total_oxygen) || total_nitrogen < 0 || isnan(total_nitrogen) || !isnum(total_nitrogen) || total_toxins < 0 || isnan(total_toxins) || !isnum(total_toxins) || total_carbon_dioxide < 0 || isnan(total_carbon_dioxide) || !isnum(total_carbon_dioxide) || total_sleeping_agent < 0 || isnan(total_sleeping_agent) || !isnum(total_sleeping_agent) || total_agent_b < 0 || isnan(total_agent_b) || !isnum(total_agent_b) || total_hydrogen < 0 || isnan(total_hydrogen) || !isnum(total_hydrogen))
+	if(total_volume < 0 || isnan(total_volume) || !isnum(total_volume) || total_oxygen < 0 || isnan(total_oxygen) || !isnum(total_oxygen) || total_nitrogen < 0 || isnan(total_nitrogen) || !isnum(total_nitrogen) || total_toxins < 0 || isnan(total_toxins) || !isnum(total_toxins) || total_carbon_dioxide < 0 || isnan(total_carbon_dioxide) || !isnum(total_carbon_dioxide) || total_sleeping_agent < 0 || isnan(total_sleeping_agent) || !isnum(total_sleeping_agent) || total_agent_b < 0 || isnan(total_agent_b) || !isnum(total_agent_b) || total_hydrogen < 0 || isnan(total_hydrogen) || !isnum(total_hydrogen) || total_water_vapor < 0 || isnan(total_water_vapor) || !isnum(total_water_vapor))
 		CRASH("A pipenet with [length(mixtures)] connected airs is corrupt and cannot flow safely. Pipenet root is [root] at ([root.x], [root.y], [root.z]).")
 
 	// If we don't have a significant temperature difference, check for a significant gas amount difference.
@@ -843,6 +894,9 @@ What are the archived variables for?
 			if(abs(G.private_hydrogen - total_hydrogen * G.volume / total_volume) > 0.1)
 				must_share = TRUE
 				break
+			if(abs(G.private_water_vapor - total_water_vapor * G.volume / total_volume) > 0.1)
+				must_share = TRUE
+				break
 
 	if(!must_share)
 		// Nothing significant, don't do any more work.
@@ -877,6 +931,7 @@ What are the archived variables for?
 		G.private_sleeping_agent = total_sleeping_agent * G.volume / total_volume
 		G.private_agent_b = total_agent_b * G.volume / total_volume
 		G.private_hydrogen = total_hydrogen * G.volume / total_volume
+		G.private_water_vapor = total_water_vapor * G.volume / total_volume
 
 		G.private_temperature = temperature
 		// In theory, we should G.set_dirty() here, but that's only useful for bound mixtures, and these can't be.
@@ -890,6 +945,7 @@ What are the archived variables for?
 #undef SPECIFIC_HEAT_N2O
 #undef SPECIFIC_HEAT_AGENT_B
 #undef SPECIFIC_HEAT_HYDROGEN
+#undef SPECIFIC_HEAT_WATER_VAPOR
 #undef HEAT_CAPACITY_CALCULATION
 #undef MINIMUM_HEAT_CAPACITY
 #undef MINIMUM_MOLE_COUNT
@@ -917,6 +973,7 @@ What are the archived variables for?
 		readonly.private_sleeping_agent = private_sleeping_agent
 		readonly.private_agent_b = private_agent_b
 		readonly.private_hydrogen = private_hydrogen
+		readonly.private_water_vapor = private_water_vapor
 		readonly.private_temperature = private_temperature
 		readonly.private_hotspot_temperature = private_hotspot_temperature
 		readonly.private_hotspot_volume = private_hotspot_volume
@@ -955,6 +1012,10 @@ What are the archived variables for?
 	private_hydrogen = value
 	set_dirty()
 
+/datum/gas_mixture/bound_to_turf/set_water_vapor(value)
+	private_water_vapor = value
+	set_dirty()
+
 /datum/gas_mixture/bound_to_turf/set_temperature(value)
 	private_temperature = value
 	set_dirty()
@@ -975,6 +1036,7 @@ What are the archived variables for?
 		sleeping_agent = private_sleeping_agent,
 		agent_b = private_agent_b,
 		hydrogen = private_hydrogen,
+		water_vapor = private_water_vapor,
 		temperature = private_temperature
 	)
 /datum/gas_mixture/bound_to_turf/proc/get_readonly()
@@ -993,6 +1055,7 @@ What are the archived variables for?
 	private_sleeping_agent = parent.private_sleeping_agent
 	private_agent_b = parent.private_agent_b
 	private_hydrogen = parent.private_hydrogen
+	private_water_vapor = parent.private_water_vapor
 
 	private_temperature = parent.private_temperature
 	private_hotspot_temperature = parent.private_hotspot_temperature
@@ -1023,5 +1086,8 @@ What are the archived variables for?
 /datum/gas_mixture/readonly/set_hydrogen(value)
 	CRASH("Attempted to modify a readonly gas_mixture.")
 
+/datum/gas_mixture/readonly/set_water_vapor(value)
+	CRASH("Attempted to modify a readonly gas_mixture.")
+
 /datum/gas_mixture/readonly/set_temperature(value)
 	CRASH("Attempted to modify a readonly gas_mixture.")

code/modules/atmospherics/machinery/airalarm.dm

@@ -152,6 +152,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 		"plasma"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 		"nitrous oxide"  = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 		"hydrogen"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
+		"water vapor"      = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 		"other"          = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 		"pressure"       = new/datum/tlv(ONE_ATMOSPHERE*0.80,ONE_ATMOSPHERE*0.90,ONE_ATMOSPHERE*1.10,ONE_ATMOSPHERE*1.20), /* kpa */
 		"temperature"    = new/datum/tlv(T0C, T0C+10, T0C+40, T0C+66), // K
@@ -165,6 +166,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				"plasma"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 				"nitrous oxide"  = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 				"hydrogen"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
+				"water vapor"      = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 				"other"          = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 				"pressure"       = new/datum/tlv(ONE_ATMOSPHERE*0.80,ONE_ATMOSPHERE*0.90,ONE_ATMOSPHERE*1.10,ONE_ATMOSPHERE*1.20), /* kpa */
 				"temperature"    = new/datum/tlv(T0C, T0C+10, T0C+40, T0C+66), // K
@@ -177,6 +179,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				"plasma"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 				"nitrous oxide"  = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
 				"hydrogen"         = new/datum/tlv(-1.0, -1.0, 0.2, 0.5), // Partial pressure, kpa
+				"water vapor"      = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 				"other"          = new/datum/tlv(-1.0, -1.0, 0.5, 1.0), // Partial pressure, kpa
 				"pressure"       = new/datum/tlv(ONE_ATMOSPHERE*0.80,ONE_ATMOSPHERE*0.90,ONE_ATMOSPHERE*1.50,ONE_ATMOSPHERE*1.60), /* kpa */
 				"temperature"    = new/datum/tlv(T0C-50, T0C-20, T0C, T20C), // K
@@ -189,6 +192,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				"plasma"         = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"nitrous oxide"  = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"hydrogen"         = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
+				"water vapor"      = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"other"          = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"pressure"       = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), /* kpa */
 				"temperature"    = new/datum/tlv(0, 0, T20C + 5, T20C + 15), // K
@@ -202,6 +206,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				"plasma"         = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"nitrous oxide"  = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"hydrogen"         = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
+				"water vapor"      = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"other"          = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // Partial pressure, kpa
 				"pressure"       = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), /* kpa */
 				"temperature"    = new/datum/tlv(-1.0, -1.0, -1.0, -1.0), // K
@@ -302,6 +307,9 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 	cur_tlv = TLV["hydrogen"]
 	var/hydrogen_dangerlevel = cur_tlv.get_danger_level(environment.hydrogen() * GET_PP)
 
+	cur_tlv = TLV["water vapor"]
+	var/water_vapor_dangerlevel = cur_tlv.get_danger_level(environment.water_vapor() * GET_PP)
+
 	cur_tlv = TLV["other"]
 	var/other_dangerlevel = cur_tlv.get_danger_level(environment.total_trace_moles() * GET_PP)
 
@@ -317,6 +325,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 		plasma_dangerlevel,
 		sleeping_agent_dangerlevel,
 		hydrogen_dangerlevel,
+		water_vapor_dangerlevel,
 		other_dangerlevel,
 		temperature_dangerlevel
 	)
@@ -420,6 +429,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				S.scrub_Toxins = FALSE
 				S.scrub_N2O = FALSE
 				S.scrub_H2 = FALSE
+				S.scrub_H2O = FALSE
 				S.scrubbing = TRUE
 				S.widenet = FALSE
 				S.update_icon(UPDATE_ICON_STATE)
@@ -442,6 +452,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				S.scrub_Toxins = TRUE
 				S.scrub_N2O = TRUE
 				S.scrub_H2 = TRUE
+				S.scrub_H2O = TRUE
 				S.scrubbing = TRUE
 				S.widenet = TRUE
 				S.update_icon(UPDATE_ICON_STATE)
@@ -482,6 +493,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 				S.scrub_Toxins = FALSE
 				S.scrub_N2O = FALSE
 				S.scrub_H2  = FALSE
+				S.scrub_H2O = FALSE
 				S.scrubbing = TRUE
 				S.widenet = FALSE
 				S.update_icon(UPDATE_ICON_STATE)
@@ -635,6 +647,10 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 	var/hydrogen_dangerlevel = cur_tlv.get_danger_level(environment.hydrogen() * GET_PP)
 	var/hydrogen_percent = total ? environment.hydrogen() / total * 100 : 0
 
+	cur_tlv = TLV["water vapor"]
+	var/water_vapor_dangerlevel = cur_tlv.get_danger_level(environment.water_vapor() * GET_PP)
+	var/water_vapor_percent = total ? environment.water_vapor() / total * 100 : 0
+
 	cur_tlv = TLV["other"]
 	var/other_moles = total - known_total
 	var/other_dangerlevel = cur_tlv.get_danger_level(other_moles*GET_PP)
@@ -656,6 +672,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 	percentages["plasma"] = plasma_percent
 	percentages["n2o"] = sleeping_agent_percent
 	percentages["hydrogen"] = hydrogen_percent
+	percentages["water_vapor"] = water_vapor_percent
 	percentages["other"] = other_percent
 	data["contents"] = percentages
 
@@ -668,8 +685,9 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 	danger["plasma"] = plasma_dangerlevel
 	danger["n2o"] = sleeping_agent_dangerlevel
 	danger["hydrogen"] = hydrogen_dangerlevel
+	danger["water_vapor"] = water_vapor_dangerlevel
 	danger["other"] = other_dangerlevel
-	danger["overall"] = max(pressure_dangerlevel,oxygen_dangerlevel,nitrogen_dangerlevel,co2_dangerlevel,plasma_dangerlevel,hydrogen_dangerlevel,other_dangerlevel,temperature_dangerlevel)
+	danger["overall"] = max(pressure_dangerlevel,oxygen_dangerlevel,nitrogen_dangerlevel,co2_dangerlevel,plasma_dangerlevel,hydrogen_dangerlevel,water_vapor_dangerlevel,other_dangerlevel,temperature_dangerlevel)
 	data["danger"] = danger
 	return data
 
@@ -744,6 +762,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 			scrubber_info["filter_toxins"] = S.scrub_Toxins
 			scrubber_info["filter_n2o"] = S.scrub_N2O
 			scrubber_info["filter_h2"] = S.scrub_H2
+			scrubber_info["filter_h2o"] = S.scrub_H2O
 			scrubbers += list(scrubber_info)
 	data["scrubbers"] = scrubbers
 	return data
@@ -772,6 +791,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 		"plasma"         = "Toxin",
 		"nitrous oxide"  = "N2O",
 		"hydrogen"		 = "H2",
+		"water vapor"    = "H2O",
 		"other"          = "Other")
 	for(var/g in gas_names)
 		thresholds += list(list("name" = gas_names[g], "settings" = list()))
@@ -886,6 +906,7 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 					"n2_scrub",
 					"o2_scrub",
 					"h2_scrub",
+					"h2o_scrub",
 					"widenet",
 					"scrubbing",
 					"direction")
@@ -950,6 +971,8 @@ GLOBAL_LIST_INIT(aalarm_modes, list(
 								S.scrub_O2 = val
 							if("h2_scrub")
 								S.scrub_H2 = val
+							if("h2o_scrub")
+								S.scrub_H2O = val
 							if("widenet")
 								S.widenet = val
 							if("scrubbing")

code/modules/atmospherics/machinery/components/trinary_devices/filter.dm

@@ -13,6 +13,8 @@
 #define FILTER_N2O 4
 /// Hydrogen only.
 #define FILTER_H2  5
+/// Water vapor only.
+#define FILTER_H2O 6
 
 /obj/machinery/atmospherics/trinary/filter
 	name = "gas filter"
@@ -32,6 +34,7 @@
 		"CO2" = FILTER_CO2,
 		"N2O" = FILTER_N2O,
 		"H2"  = FILTER_H2,
+		"H2O" = FILTER_H2O,
 	)
 
 // So we can CtrlClick without triggering the anchored message.
@@ -151,6 +154,11 @@
 			if(FILTER_H2)
 				filtered_out.set_hydrogen(removed.hydrogen())
 				removed.set_hydrogen(0)
+
+			if(FILTER_H2O)
+				filtered_out.set_water_vapor(removed.water_vapor())
+				removed.set_water_vapor(0)
+
 			else
 				filtered_out = null
 
@@ -248,3 +256,4 @@
 #undef FILTER_CO2
 #undef FILTER_N2O
 #undef FILTER_H2
+#undef FILTER_H2O

code/modules/atmospherics/machinery/components/unary_devices/vent_scrubber.dm

@@ -24,6 +24,7 @@
 	var/scrub_Toxins = FALSE
 	var/scrub_N2O = FALSE
 	var/scrub_H2 = FALSE
+	var/scrub_H2O = FALSE
 
 	var/volume_rate = 200
 	var/widenet = FALSE //is this scrubber acting on the 3x3 area around it.
@@ -168,6 +169,8 @@
 		return TRUE
 	if(environment.hydrogen() > 0.001)
 		return TRUE
+	if(environment.water_vapor() > 0.001)
+		return TRUE
 
 	return FALSE
 
@@ -216,6 +219,10 @@
 				filtered_out.set_hydrogen(removed.hydrogen())
 				removed.set_hydrogen(0)
 
+			if(scrubber.scrub_H2O)
+				filtered_out.set_water_vapor(removed.water_vapor())
+				removed.set_water_vapor(0)
+
 			//Remix the resulting gases
 			scrubber.air_contents.merge(filtered_out)
 

code/modules/atmospherics/machinery/portable/canister.dm

@@ -8,6 +8,7 @@
 		list("name" = "\[Toxin (Bio)\]", "icon" = "orange"),
 		list("name" = "\[CO2\]", "icon" = "black"),
 		list("name" = "\[H2\]", "icon" = "white"),
+		list("name" = "\[H2O\]", "icon" = "lightgrey"),
 		list("name" = "\[Air\]", "icon" = "grey"),
 		list("name" = "\[CAUTION\]", "icon" = "yellow"),
 		list("name" = "\[SPECIAL\]", "icon" = "whiters")
@@ -445,6 +446,11 @@ GLOBAL_DATUM_INIT(canister_icon_container, /datum/canister_icons, new())
 	name = "Canister \[H2\]"
 	icon_state = "white" //See Initialize()
 	can_label = FALSE
+/obj/machinery/atmospherics/portable/canister/water_vapor
+	name = "Canister \[H2O\]"
+	icon_state = "lightgrey" //See Initialize()
+	can_label = FALSE
+	
 /obj/machinery/atmospherics/portable/canister/air
 	name = "Canister \[Air\]"
 	icon_state = "grey" //See Initialize()
@@ -504,6 +510,14 @@ GLOBAL_DATUM_INIT(canister_icon_container, /datum/canister_icons, new())
 
 	update_icon()
 
+/obj/machinery/atmospherics/portable/canister/water_vapor/Initialize(mapload)
+	. = ..()
+	
+	canister_color["prim"] = "lightgrey"
+	air_contents.set_water_vapor((maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature()))
+	
+	update_icon()
+
 /obj/machinery/atmospherics/portable/canister/air/Initialize(mapload)
 	. = ..()
 

code/modules/atmospherics/machinery/portable/scrubber.dm

@@ -93,6 +93,9 @@
 		filtered_out.set_hydrogen(removed.hydrogen())
 		removed.set_hydrogen(0)
 
+		filtered_out.set_water_vapor(removed.water_vapor())
+		removed.set_water_vapor(0)
+
 		//Remix the resulting gases
 		air_contents.merge(filtered_out)
 

code/modules/buildmode/submodes/atmos.dm

@@ -11,6 +11,7 @@
 	var/nitrox = 0
 	var/agentbx = 0
 	var/hydrogen = 0
+	var/water_vapor = 0
 
 
 /datum/buildmode_mode/atmos/show_help(mob/user)
@@ -33,6 +34,7 @@
 	nitrox = tgui_input_number(user, "N2O ratio", "Input", 0, 100000, 0, round_value = FALSE)
 	agentbx = tgui_input_number(user, "Agent B ratio", "Input", 0, 100000, 0, round_value = FALSE)
 	hydrogen = tgui_input_number(user, "Hydrogen ratio", "Input", 0, 100000, 0, round_value = FALSE)
+	water_vapor = tgui_input_number(user, "Water Vapor ratio", "Input", 0, 100000, 0, round_value = FALSE)
 
 /datum/buildmode_mode/atmos/proc/ppratio_to_moles(ppratio)
 	// ideal gas equation: Pressure * Volume = Moles * r * Temperature
@@ -54,6 +56,7 @@
 		air.set_sleeping_agent(ppratio_to_moles(nitrox))
 		air.set_agent_b(ppratio_to_moles(agentbx))
 		air.set_hydrogen(ppratio_to_moles(hydrogen))
+		air.set_water_vapor(ppratio_to_moles(water_vapor))
 
 		for(var/turf/T in block(cornerA,cornerB))
 			if(issimulatedturf(T))
@@ -70,6 +73,7 @@
 				T.sleeping_agent = air.sleeping_agent()
 				T.agent_b = air.agent_b()
 				T.hydrogen = air.hydrogen()
+				T.water_vapor = air.water_vapor()
 
 		// admin log
 		log_admin("Build Mode: [key_name(user)] changed the atmos of region [COORD(cornerA)] to [COORD(cornerB)]. T: [temperature], P: [pressure], Ox: [oxygen]%, N2: [nitrogen]%, Plsma: [plasma]%, CO2: [cdiox]%, N2O: [nitrox]%. [ctrl_click ? "Overwrote base space turf gases." : ""]")

code/modules/mob/mob.dm

@@ -112,6 +112,7 @@
 	t+= "<span class='notice'>N2O: [environment.sleeping_agent()] \n</span>"
 	t+= "<span class='notice'>Agent B: [environment.agent_b()] \n</span>"
 	t+= "<span class='notice'>Hydrogen: [environment.hydrogen()] \n</span>"
+	t+= "<span class='notice'>Water Vapor: [environment.water_vapor()] \n</span>"
 
 	usr.show_message(t, EMOTE_VISIBLE)
 

code/modules/pda/core_apps.dm

@@ -115,7 +115,8 @@
 			var/plasma_level = environment.toxins() / total_moles
 			var/n2o_level = environment.sleeping_agent() / total_moles
 			var/h2_level = environment.hydrogen() / total_moles
-			var/unknown_level = 1 - (o2_level + n2_level + co2_level + plasma_level + n2o_level + h2_level)
+			var/h2o_level = environment.water_vapor() / total_moles
+			var/unknown_level = 1 - (o2_level + n2_level + co2_level + plasma_level + n2o_level + h2_level + h2o_level)
 			results = list(
 				list("entry" = "Pressure", "units" = "kPa", "val" = "[round(pressure,0.1)]", "bad_high" = 120, "poor_high" = 110, "poor_low" = 95, "bad_low" = 80),
 				list("entry" = "Temperature", "units" = "C", "val" = "[round(environment.temperature()-T0C,0.1)]", "bad_high" = 35, "poor_high" = 25, "poor_low" = 15, "bad_low" = 5),
@@ -125,6 +126,7 @@
 				list("entry" = "Plasma", "units" = "%", "val" = "[round(plasma_level*100,0.01)]", "bad_high" = 0.5, "poor_high" = 0, "poor_low" = 0, "bad_low" = 0),
 				list("entry" = "Nitrous Oxide", "units" = "%", "val" = "[round(n2o_level*100,0.01)]", "bad_high" = 0.5, "poor_high" = 0, "poor_low" = 0, "bad_low" = 0),
 				list("entry" = "Hydrogen", "units" = "%", "val" = "[round(h2_level*100,0.01)]", "bad_high" = 0.5, "poor_high" = 0, "poor_low" = 0, "bad_low" = 0),
+				list("entry" = "Water Vapor", "units" = "%", "val" = "[round(h2o_level*100,0.1)]", "bad_high" = 100, "poor_high" = 80, "poor_low" = 0, "bad_low" = 0),
 				list("entry" = "Other", "units" = "%", "val" = "[round(unknown_level*100,0.01)]", "bad_high" = 1, "poor_high" = 0.5, "poor_low" = 0, "bad_low" = 0)
 			)
 

code/modules/power/electrolyzer.dm

@@ -0,0 +1,142 @@
+/obj/machinery/power/electrolyzer
+	name = "gas electrolyzer"
+	desc = "A nifty little machine that is able to produce hydrogen when supplied with water vapor and enough power, allowing for on-the-go hydrogen production! Nanotrasen is not responsible for any accidents that may occur from sudden hydrogen combustion or explosions. It seems it needs around 350 kW of power to funtion properly."
+	anchored = FALSE
+	icon = 'icons/obj/atmos.dmi'
+	icon_state = "electrolyzer_off"
+	density = TRUE
+	active_power_consumption = 350000
+	/// whether or not we're actively using power/seeking water vapor in the air
+	var/on = FALSE
+	var/datum/gas_mixture/gas
+	var/board_path = /obj/item/circuitboard/electrolyzer
+
+/obj/machinery/power/electrolyzer/Initialize(mapload)
+	. = ..()
+	component_parts = list()
+	component_parts += new /obj/item/circuitboard/electrolyzer(src)
+	component_parts += new /obj/item/stock_parts/micro_laser(src)
+	component_parts += new /obj/item/stock_parts/micro_laser(src)
+	component_parts += new /obj/item/stock_parts/matter_bin(src)
+	component_parts += new /obj/item/stock_parts/matter_bin(src)
+	component_parts += new /obj/item/stock_parts/capacitor(src)
+	component_parts += new /obj/item/stack/cable_coil(src, 5)
+	if(!powernet)
+		connect_to_network()
+
+	if(powernet)
+		RegisterSignal(powernet)
+
+	RefreshParts()
+
+/obj/machinery/power/electrolyzer/wrench_act(mob/living/user, obj/item/I)
+	if(on)
+		return
+	. = TRUE
+	if(!I.use_tool(src, user, I.tool_volume))
+		return
+	if(!anchored)
+		connect_to_network()
+		to_chat(user, "<span class='notice'>You secure the generator to the floor.</span>")
+	else
+		disconnect_from_network()
+		to_chat(user, "<span class='notice'>You unsecure the generator from the floor.</span>")
+	anchored = !anchored
+
+/obj/machinery/power/electrolyzer/screwdriver_act(mob/user, obj/item/I)
+	. = TRUE
+	if(!anchored)
+		to_chat(user, "<span class='warning'>[src] needs to be secured down first!</span>")
+		return
+	if(on)
+		to_chat(user, "<span class='warning'>[src] needs to be turned off first!</span>")
+		return
+	if(!I.use_tool(src, user, 0, volume = I.tool_volume))
+		return
+	panel_open = !panel_open
+	if(panel_open)
+		SCREWDRIVER_OPEN_PANEL_MESSAGE
+		panel_open = TRUE
+		icon_state = "electrolyzer_open"
+	else
+		SCREWDRIVER_CLOSE_PANEL_MESSAGE
+		icon_state = "electrolyzer_off"
+		panel_open = FALSE
+
+/obj/machinery/power/electrolyzer/crowbar_act(mob/living/user, obj/item/I)
+	if(panel_open)
+		deconstruct(TRUE)
+		to_chat(user, "<span class='notice'>You disassemble [src].</span>")
+		I.play_tool_sound(user, I.tool_volume)
+		return TRUE
+	return FALSE
+
+/obj/machinery/power/electrolyzer/AltClick(mob/user)
+	if(anchored)
+		to_chat(user, "<span class='warning'>[src] is anchored to the floor!</span>")
+		return
+	pixel_x = 0
+	pixel_y = 0
+
+/obj/machinery/power/electrolyzer/Destroy()
+	if(powernet)
+		UnregisterSignal(powernet, COMSIG_POWERNET_POWER_CHANGE)
+	return ..()
+
+/datum/milla_safe/electrolyzer_process
+
+/obj/machinery/power/electrolyzer/process()
+	if(on && get_surplus() >= active_power_consumption)
+		consume_direct_power(active_power_consumption)
+		var/datum/milla_safe/electrolyzer_process/milla = new()
+		milla.invoke_async(src)
+
+// Turns the electrolyzer on and off
+/obj/machinery/power/electrolyzer/attack_hand(mob/user)
+	if(stat & BROKEN)
+		return
+	if(!anchored)
+		to_chat(user, "<span class='warning'>[src] must be anchored first!</span>")
+		return
+	if(panel_open)
+		to_chat(user, "<span class='warning'>Close the panel first!</span>")
+		return
+	var/area/A = get_area(src)
+	if(!istype(A) || !A.powernet.has_power(PW_CHANNEL_EQUIPMENT))
+		to_chat(user, "<span class='warning'>[src] must be powered!</span>")
+		return
+	. = ..()
+	if(on)
+		on = FALSE
+		to_chat(user, "<span class='notice'>[src] switches off.</span>")
+		icon_state = "electrolyzer_off"
+	else
+		on = TRUE
+		to_chat(user, "<span class='notice'>[src] begins to hum quietly.</span>")
+		icon_state = "electrolyzer_on"
+	add_fingerprint(usr)
+
+/obj/machinery/power/electrolyzer/proc/process_atmos_safely(turf/T, datum/gas_mixture/env)
+	var/datum/gas_mixture/removed = new()
+	if(env.water_vapor() > 3)
+		removed.set_water_vapor(env.water_vapor())
+		env.set_water_vapor(0)
+	return removed
+
+/obj/machinery/power/electrolyzer/proc/has_water_vapor(datum/gas_mixture/gas)
+	if(!gas)
+		return FALSE
+	return gas.water_vapor() > 3
+
+/datum/milla_safe/electrolyzer_process/on_run(obj/machinery/power/electrolyzer/electrolyzer, datum/gas_mixture)
+	var/turf/T = get_turf(electrolyzer)
+	var/datum/gas_mixture/env = get_turf_air(T)
+	var/datum/gas_mixture/removed = electrolyzer.process_atmos_safely(T, env)
+
+	if(electrolyzer.on && electrolyzer.has_water_vapor(removed))
+		var/water_vapor_to_remove = removed.water_vapor()
+		var/hydrogen_produced = water_vapor_to_remove
+		var/oxygen_produced = water_vapor_to_remove / 2
+		removed.set_water_vapor(removed.water_vapor() - water_vapor_to_remove)
+		env.set_hydrogen(env.hydrogen() + hydrogen_produced)
+		env.set_oxygen(env.oxygen() + oxygen_produced)

code/modules/power/engines/supermatter/supermatter.dm

@@ -16,10 +16,12 @@
 #define CO2_HEAT_PENALTY 0.1
 #define NITROGEN_HEAT_PENALTY -1.5
 #define HYDROGEN_HEAT_PENALTY 20
+#define H2O_HEAT_PENALTY 5
 
 #define OXYGEN_TRANSMIT_MODIFIER 1.5   //Higher == Bigger bonus to power generation.
 #define PLASMA_TRANSMIT_MODIFIER 4
 #define HYDROGEN_TRANSMIT_MODIFIER 3
+#define H2O_TRANSMIT_MODIFIER -10
 
 #define N2O_HEAT_RESISTANCE 6          //Higher == Gas makes the crystal more resistant against heat damage.
 
@@ -33,6 +35,7 @@
 #define N2O_CRUNCH 0.55
 #define PLASMA_CRUNCH 4
 #define HYDROGEN_CRUNCH 2
+#define H2O_CRUNCH 0.75
 
 #define MOLE_CRUNCH_THRESHOLD 1700           //Above this value we can get lord singulo and
 #define MOLE_PENALTY_THRESHOLD 1800           //Above this value we can get lord singulo and independent mol damage, below it we can heal damage
@@ -156,6 +159,7 @@
 	var/co2comp = 0
 	var/n2ocomp = 0
 	var/h2comp = 0
+	var/h2ocomp = 0
 
 	///The last air sample's total molar count, will always be above or equal to 0
 	var/combined_gas = 0
@@ -522,13 +526,14 @@
 		n2ocomp = max(removed.sleeping_agent() / combined_gas, 0)
 		n2comp = max(removed.nitrogen() / combined_gas, 0)
 		h2comp = max(removed.hydrogen() / combined_gas, 0)
+		h2ocomp = max(removed.water_vapor() / combined_gas, 0)
 
-		gasmix_power_ratio = min(max(plasmacomp + o2comp + co2comp + h2comp - n2comp, 0), 1)
+		gasmix_power_ratio = min(max(plasmacomp + o2comp + co2comp + h2comp + h2ocomp - n2comp, 0), 1)
 
-		dynamic_heat_modifier = max((plasmacomp * PLASMA_HEAT_PENALTY) + (o2comp * OXYGEN_HEAT_PENALTY) + (co2comp * CO2_HEAT_PENALTY) + (n2comp * NITROGEN_HEAT_PENALTY) + (h2comp * HYDROGEN_HEAT_PENALTY), 0.5)
+		dynamic_heat_modifier = max((plasmacomp * PLASMA_HEAT_PENALTY) + (o2comp * OXYGEN_HEAT_PENALTY) + (co2comp * CO2_HEAT_PENALTY) + (n2comp * NITROGEN_HEAT_PENALTY) + (h2comp * HYDROGEN_HEAT_PENALTY) + (h2ocomp * H2O_HEAT_PENALTY), 0.5)
 		dynamic_heat_resistance = max(n2ocomp * N2O_HEAT_RESISTANCE, 1)
 
-		power_transmission_bonus = max((plasmacomp * PLASMA_TRANSMIT_MODIFIER) + (o2comp * OXYGEN_TRANSMIT_MODIFIER), 0)
+		power_transmission_bonus = max((plasmacomp * PLASMA_TRANSMIT_MODIFIER) + (o2comp * OXYGEN_TRANSMIT_MODIFIER) + (h2comp * HYDROGEN_TRANSMIT_MODIFIER) + (h2ocomp * H2O_TRANSMIT_MODIFIER), 0)
 
 		//more moles of gases are harder to heat than fewer, so let's scale heat damage around them
 		mole_heat_penalty = max(combined_gas / MOLE_HEAT_PENALTY, 1)
@@ -568,7 +573,7 @@
 
 		var/crush_ratio = combined_gas / MOLE_CRUNCH_THRESHOLD
 
-		gas_coefficient = 1 + (crush_ratio ** 2 * (crush_ratio <= 1) + (crush_ratio > 1) * 2 * crush_ratio / (crush_ratio + 1)) * (plasmacomp * PLASMA_CRUNCH + o2comp * O2_CRUNCH + co2comp * CO2_CRUNCH + n2comp * N2_CRUNCH + n2ocomp * N2O_CRUNCH + h2comp * HYDROGEN_CRUNCH)
+		gas_coefficient = 1 + (crush_ratio ** 2 * (crush_ratio <= 1) + (crush_ratio > 1) * 2 * crush_ratio / (crush_ratio + 1)) * (plasmacomp * PLASMA_CRUNCH + o2comp * O2_CRUNCH + co2comp * CO2_CRUNCH + n2comp * N2_CRUNCH + n2ocomp * N2O_CRUNCH + h2comp * HYDROGEN_CRUNCH + h2ocomp * H2O_CRUNCH)
 
 		radiation_pulse(src, 6 * power * (gas_coefficient + max(0, ((power_transmission_bonus / 10)))), GAMMA_RAD)
 
@@ -1282,9 +1287,11 @@
 #undef CO2_HEAT_PENALTY
 #undef NITROGEN_HEAT_PENALTY
 #undef HYDROGEN_HEAT_PENALTY
+#undef H2O_HEAT_PENALTY
 #undef OXYGEN_TRANSMIT_MODIFIER
 #undef PLASMA_TRANSMIT_MODIFIER
 #undef HYDROGEN_TRANSMIT_MODIFIER
+#undef H2O_TRANSMIT_MODIFIER
 #undef N2O_HEAT_RESISTANCE
 #undef POWERLOSS_INHIBITION_GAS_THRESHOLD
 #undef POWERLOSS_INHIBITION_MOLE_THRESHOLD
@@ -1328,3 +1335,4 @@
 #undef N2O_CRUNCH
 #undef PLASMA_CRUNCH
 #undef HYDROGEN_CRUNCH
+#undef H2O_CRUNCH

code/modules/power/engines/supermatter/supermatter_event.dm

@@ -120,6 +120,15 @@
 	air.set_hydrogen(2000)
 	supermatter_turf.blind_release_air(air)
 
+//water vapor
+/datum/engi_event/supermatter_event/charlie_tier/water_vapor
+	name = "C-5"
+
+/datum/engi_event/supermatter_event/charlie_tier/water_vapor/on_start()
+	var/datum/gas_mixture/air = new()
+	air.set_water_vapor(2000)
+	supermatter_turf.blind_release_air(air)
+
 //Class B events
 /datum/engi_event/supermatter_event/bravo_tier
 	threat_level = SM_EVENT_THREAT_B

code/modules/procedural_mapping/mapGeneratorModules/mapgen_helpers.dm

@@ -19,6 +19,7 @@
 		air.set_sleeping_agent(T.sleeping_agent)
 		air.set_agent_b(T.agent_b)
 		air.set_hydrogen(T.hydrogen)
+		air.set_water_vapor(T.water_vapor)
 		air.set_temperature(T.temperature)
 		T.blind_set_air(air)
 

code/modules/station_goals/bluespace_tap_events.dm

@@ -30,7 +30,7 @@
 
 /datum/engi_event/bluespace_tap_event/gas/on_start()
 	var/datum/gas_mixture/air = new()
-	var/picked_gas = pick("N2O", "N2", "O2", "CO2", "Plasma", "Unknown", "H2")
+	var/picked_gas = pick("N2O", "N2", "O2", "CO2", "Plasma", "Unknown", "H2", "H2O")
 	switch(picked_gas)
 		if("N2")
 			name = "G-1"
@@ -53,6 +53,9 @@
 		if("H2")
 			name = "G-7"
 			air.set_hydrogen(250)
+		if("H2O")
+			name = "G-8"
+			air.set_water_vapor(250)
 
 	air.set_temperature(T20C)
 	var/turf/tap_turf = get_turf(tap)