Changes

Regulations require holding tanks to be an integral part of the hull, or similarly securely attached. If attached, a [https://en.wikipedia.org/wiki/Neoprene neoprene ] buffer should be used between the tank and any chafing points. Tanks must have an external level indicator, and a ventilation system fitted with a flame screen. The level indicator must show when the tank is ¾ full (USA regulation 33 CFR 159.83). Consider an alarm when 75% full. If the output pipe is fitted with “Y” valves, to switch between pump-out and overboard discharge, the “Y” valve must be padlocked in Canadian waters so that sewage cannot be pumped overboard. Similar restrictions apply in USA No Discharge areas.

The holding tank is located central to the toilets and mounted as low as possible, especially for gravity-type [[MarineToilet|marine toilets]]. This reduces the length of piping needed, and effects on the trim of the boat.  [[File:HoldingTankLayour.png|250px|thumb|left|Layout of the holding tank (source unknown]] Connections include: