Waste and Trash/garbage should be added to the house system. The bathroom items like Latrine should generate "waste" like the stove generates pollution. You must use pipes to empty the latrine in order to continue gaining SP from the bathroom. The latrine item's SP should be doubled to reflect this.
Further, there should be a "wastebin" added to the bathroom/general that turns trash/garbage into pollution that can be piped out, instead of stored as solid. The trash bin could also be used for things such as creating compost/fertlizer from the trash.
Trash should also be able to be "compacted" into smaller units that create more pollution. Alternatively, you could be able to turn liquid latrine waste into permanent solid waste if you cannot pipe it out yet.