MarineToilet

Heads

Marine toilets are gravity, push or pull.

Gravity types are simple but have to be placed higher then the holding tank. Plumbing has to be fairly straight and downhill. The best location for a gravity head is on the main deck more or less above the holding tank.

The push type uses gravity, compressed air, water-hydraulics, or a manual or electrical pump to evacuate the toilet and push the contents through the pipes to the holding tank.

The pull type uses a vacuum to suck the contents from the toilet down to the holding tank. Of these, only three types are suited to a yacht:

• Manual pump (push)
• Electric (including macerating) (push)
• Vacuum (pull)

In all cases, look for a four-bolt model that minimizes the amount of water in a flush, to avoid the need for an overly large holding tank.

Manual Pump

AAmpere (amp), SI unit of electrical current manual-pump head typically uses a foot pedal or handle to activate a manual pump to send the effluent to the holding tank. Manual pump heads are not dependent on electrical power, thus reducing the demand on the electrical system. They are very dependable and easier to install, and have relatively low maintenance costs. They can use seawater for flushing. Chief disadvantages are that users must learn how to use the pump (open the intake valve, select a dry or a wet position); users may not know if the flush is complete to the holding tank; and pipes can get clogged.

Typical vendors are Groco, Jabsco (includes Par], Blake Lavac, Raritan and Wilcox Crittenden (now Thetford).

Electric Head

An electric head uses an electrical pump, operated by a switch. Electric heads obviously impose a demand on the electrical system. They are moderately difficult to install. Typically they also macerate solid waste, reducing the possibility of clogged pipes. They are easy to use, and can be fitted with a manual pump for backup.

The chief disadvantage of electric heads is that users may not know if the flush is complete to the holding tank. So they either flush too little, leaving waste in the pipes, or flush too much, using excessive water. Macerating heads require more water to flush than any other type of head – as much as three gallons for solids. Typical vendors are Headhunter, Jabsco (includes Par], Blake Lavac, Raritan, Tecma, Vetus and Wilcox Crittenden (now Thetford).

Vacuum Flush

There are only two vacuum flush systems on the market: Dometic’sSecond electric SeaLand VacuFlush [13] and Lavac’s manual or electric Zenith [8]. The VacuFlush uses an electric pump to create a vacuum in the system. When a lever is operated, the vacuum sucks the sewage into the holding tank. It uses pressurized fresh water, and only uses 1-3 pints per flush. It requires very little preventative maintenance. Because it uses the onboard water supply, it is subject to ABYCAmerican Boat and Yacht Council standard H-23, Installation of Potable Water System.

Marine bidets are available from Dometic Corporation, Headhunter, and Tecma (Silence, Sarinautico).

Pumps

Pumps are diaphragm- or piston-types. Diaphragm pumps can be manual or electric. They pass solids better than piston pumps. They can be run dry without damage. Their simple design makes them more robust and easier to maintain.

Macerator electric pumps are used at the toilet to mush up the solids. They reduce the amount of water needed for flushing and minimize the risk of clogged pipes. They can burn up if the pump is run dry.

Pumps should be rated for sewage. Bronze pumps are the most rugged. Aluminium pumps are subject to corrosion. Plastic pumps are resistant to corrosion but likely to leak.

Through Hulls and Hoses

See HoldingTank#Through_Hulls for toilet intake and overboard discharge lines.