(Excerpt from Practical Boat Improvement Projects)


Countless boats have been flooded or sunk by malfunctioning toilets. Your best defense against these troublesome beasts is to put them where they belong – behind a watertight bulkhead.

One of the least understood and most vilified pieces of equipment aboard our boats is the toilet - or as sailors like to refer to it - The Head. The old salts among us tend to cling to this bit of archaic nautical jargon to remind ourselves of the days when the only toilet facilities aboard sailing ships was to saunter up forward to the bow, or head of the ship, and let your backside hang over the side. Nothing wrong with tradition, but I know a toilet when I see one.

After 20 years of working on and living on boats, I've come to two conclusions. First, the only thing that's more likely to break down and be more disagreeable to work on than the inboard engine is the marine toilet. Second, the only thing more likely to sink your boat than the engine is your toilet. Like the engine, the toilet commonly sits below the waterline and has sea water running through its various intricate and delicate valves and chambers. Most marine toilets built today look like they were designed by the same man who built the first steam engine. They hiss, gurgle, leak and plug up. If you pump too hard to clear an obstruction they may even blow up in your face! The day inevitably comes when every cruising sailor has the memorable experience of attempting to repair a plugged or leaking toilet at sea. Between bouts of seasickness he works with scraped knuckles, covered to the elbows in sewage while the disassembled and unidentifiable toilet components roll around the cabin floor and into the bilge.

After gaining much (unwanted) experience installing and repairing many different types of marine toilets, I eventually discovered a safe and reliable toilet to install aboard my Triton, Atom. The toilet is called a Lavac and is made in England. Its design is simple and ingenious. The toilet itself has no moving parts – it operates by vacuum. It comes with a standard Henderson manual bilge pump that mounts separately on a bulkhead. A hose from the inlet of the bilge pump connects to the toilet outlet. The outlet of the bilge pump leads to the discharge seacock, or to the holding tank, if you have one. To flush the toilet, the lid, which has a rubber seal under it, is lowered. By giving about ten good strokes on the pump, a vacuum is created within the bowl, which sucks the bowl dry, and simultaneously draws rinse water in at the top of the bowl. The Lavac is available through

Since my cockpit mounted bilge pump is also a Henderson, one spare rebuild kit can service either one. I also carry an extra rubber seal for the toilet lid. Another practical point is that a Y-valve can easily be installed in the toilet pump inlet and another hose led from it to the bilge to allow the toilet pump to also work as a bilge pump. If you agree that for safety, every boat should have a hand-operated inside mounted bilge pump, then this is an ideal situation. The only maintenance I've done since installing this toilet four years ago is to occasionally pump some vinegar through the system to prevent calcium deposits in the hoses. The Lavac costs two to three times more than its cheapest competitors, but for me it's worth the price.

Now that I had a reasonably trouble-free toilet I was still concerned about accidental flooding, either through the bowl back-siphoning and overflowing or through a hose or seacock failure. To prevent back-siphoning I raised the toilet so that its rim was above the boats waterline by placing it on a wooden box about 150mm high. To guard against any leaks in the plumbing system I placed a plywood bulkhead in front of the toilet reaching from the floor to above the waterline and just below the toilet seat. The bulkhead was screwed in place to make it removable for future maintenance and was made watertight along its edges with Sikaflex. The top edge of the bulkhead is trimmed with a narrow strip of teak. The bulkhead is placed as close to the toilet as possible and angled in slightly at the bottom to allow for comfortable seating.

The only real complaint I ever heard from a Lavac owner was from a friend who was prone to seasickness. With a Lavac you have to wait about 30 seconds after pumping before you can re-open the lid in order to give the vacuum enough time to bleed off. Normally this is no problem, but on a rough passage around the South African Cape my friend was unhappily embracing the Lavac for the first time and noisily giving up her lunch, when she decided a little too soon that she was finished. She closed the lid, gave it the requisite ten pumps and immediately realized she wasn't finished after all. To her horror she found the lid would not open no matter how many fingernails she broke in the attempt. The result was not a pretty sight.

For further information on Atom's improvement projects, check out his website at