The Small Duck Valve That Can Cause a Big Problem

Vacuum flush toilets, like the VacuFlush systems found on many cruisers, use very little water and are a pleasure to use when they’re working. But they rely on a few small rubber valves to hold the vacuum, and when one of those valves fails, the whole system stops working properly.

What does a duck valve do?

Duck valves (named for their shape, like a duck’s bill) are one-way rubber valves that let waste through and then close tightly to hold the vacuum in the system. Most vacuum systems have several of them, usually in the vacuum pump.

How build-up causes problems

Every flush leaves a little urine and waste on the valve lips. Over time this forms crystallisation and sludge that stops the valve from sealing. The signs are easy to spot:

the vacuum pump cycles on and off when no one has flushed
the toilet takes longer to build vacuum
odours come from the pump area
the pump runs for longer than it should.

Replacing duck valves is a messy job, and the new valves will clog in exactly the same way unless the cause is treated.

A preventative clean you can do every trip

ProPower Marine‘s microbes break down the organic material and crystallisation on the valves, keeping them supple and sealing properly. The trick is to get the product into the vacuum system and leave it there:

Mix 20 mL of ProPower Marine into a glass of water.
Pour it into the toilet bowl.
Turn off the vacuum system.
Flush once. The mixture goes into the vacuum tank and lines without being pumped away.
Leave it there until you’re next on board.

Used regularly, this can form part of a preventative maintenance routine for the valves, vacuum tank and the start of the pipework.

Shop and learn more: ProPower Marine Tank Treatment · Dosing guides