as requested

code/game/objects/structures/watercloset.dm

@@ -63,7 +63,7 @@
 			return
 		var/obj/item/weapon/reagent_containers/RG = I
 		if(RG.is_open_container())
-			RG.reagents.add_reagent("water", min(RG.volume - RG.reagents.total_volume, RG.amount_per_transfer_from_this))
+			RG.reagents.add_reagent("toiletwater", min(RG.volume - RG.reagents.total_volume, RG.amount_per_transfer_from_this))
 			user << "<span class='notice'>You fill [RG] from [src]. Gross.</span>"
 			return
 

code/modules/reagents/oldchem/reagents/reagents_water.dm

@@ -223,9 +223,18 @@
 			M.fakevomit(1)
 		else
 			M.fakevomit(0)
-		..()
+	..()
 	return
 
+/datum/reagent/fishwater/toiletwater
+	name = "Toilet Water"
+	id = "toiletwater"
+	description = "Filthy water scoured from a nasty toilet bowl. Absolutely disgusting."
+	reagent_state = LIQUID
+	color = "#757547"
+
+/datum/reagent/fishwater/toiletwater/reaction_mob(var/mob/M, var/method=TOUCH, var/volume) //For shennanigans
+	return
 
 /datum/reagent/holywater
 	name = "Water"