Oh, that kind of list

code/game/objects/structures/janicart.dm

@@ -232,11 +232,11 @@
 
 /obj/structure/janitorialcart/New()
 	create_reagents(100)
-	janitorialcarts += src
+	janitorial_equipment += src
 
 
 /obj/structure/janitorialcart/Destroy()
-	janitorialcarts -= src
+	janitorial_equipment -= src
 	return ..()
 
 /obj/structure/janitorialcart/proc/wet_mop(obj/item/weapon/mop, mob/user)

code/game/objects/structures/mop_bucket.dm

@@ -11,11 +11,16 @@
 	var/datum/reagents/R = new/datum/reagents(100)
 	reagents = R
 	R.my_atom = src
+	janitorial_equipment += src
 
 /obj/structure/mopbucket/full/New()
 	..()
 	reagents.add_reagent("water", 100)
 
+/obj/structure/mopbucket/Destroy()
+	janitorial_equipment -= src
+	return ..()
+
 /obj/structure/mopbucket/examine(mob/user)
 	if(..(user, 1))
 		usr << text("\icon[] [] contains [] units of water left!", src, src.name, src.reagents.total_volume)