My Lavac empties into a custom ply/epoxy holding tank
, mounted as high up under the foredeck as possible, allowing for the curve of the hose entering the top. At the base of the holding tank, I have installed a tee in the exhaust
line, with the additional hose leading to a deck
pumpout fitting. The direct waste drain then goes to a large plastic ball valve, turns 90 degrees into the thruhull fitting (located just ABOVE the waterline). With the waste valve closed (and LOCKED, per USCG), the unit is perfectly acceptable by the authorities. In open ocean areas, simply open the ball valve for instant, GRAVITY-FED, not electrically macerated and pumped, discharge.
The vent lines on the tank reveal the secret, though. Instead of the usual single
1/2 inch hose found on most holding tanks
, mine has two vent lines, each 1 1/2 inches in diameter, which lead to opposite sides of the bow, near deck
level. This is to allow strong cross drafting of air through the top of the holding tank. The reason for all of this? Aerobic digestion of the waste in the tank, supported by bacteria from K.O., a product sold at West Marine
, and other sites. My boat is the only one on the dock
that doesn't have a smelly head
. The odors are generated by anerobic (live in the absence of oxygen) bacteria, as well as the formaldehyde and perfumes added by conventional head chemicals. The stuff works and is the perfect complement to the Lavac installation
When underway, there is no need to lug along a hundred pounds of toilet waste. If you are in open waters and feel the need to have a personal waste discharge, the Lavac pumps the poop up and into the tank, where it flows downward and out the throughhull. A couple more pumps and the lines and tank are rinsed relatively clean. Later, with a fresh batch of K.O. and some seawater, the bugs are gobbling up any available waste in the lines or tank, turning them into environmentally safe building blocks for other forms of marine
life. This is actually how septic tanks
work on land, and allow human waste to enter the earth safely, even when one is pumping drinking water
a hundred yards away.
The best parts
, though, beside the good vibes and no nasty smells, are that things work without costly maintenance
, they work flawlessly, and don't cost you very much at all. And it weighs very little, in the bargain.
Pictures: Pump up -gravity out holding tanks