Boat toilet maintenance tips for Kiwi boaties
The first warm weekends of spring bring a lot of boats out for their first proper outing. They're also when the toilet tends to make itself known. A head that has sat unused over winter can be stiff, smelly or blocked, and once that happens on board, the day is pretty much over.
Most toilet problems are slow to develop. Scale builds up, seals dry out and hoses start to smell. A quick check before your first trip, alongside the rest of your spring boat preparation, then a simple routine through the season, will head off nearly all of them.
How a marine toilet works
Most launches and yachts in New Zealand have a manual marine toilet. A hand pump draws seawater in through an inlet seacock to rinse the bowl, then pushes waste out through a discharge hose to a holding tank or overboard.
A rubber one-way valve called the joker valve stops waste flowing back into the bowl. Many boats also have a Y-valve to switch between the tank and overboard, and an anti-siphon valve to stop seawater siphoning back in. Electric toilets work the same way, with a motor and macerator doing the pumping.
Spring recommissioning checklist
- Seacocks. Open and close the inlet and outlet seacocks several times. A seacock that has seized over winter needs freeing up or servicing before you head out.
- Hoses and clamps. Check every hose for cracks, bulging or stiffness. Connections below the waterline should be double clamped with stainless steel clamps, and any rusty clamps replaced.
- Joker valve. If water creeps back into the bowl after flushing, the joker valve is likely worn. Many owners replace it every season or two, since it's cheap and easy to change.
- Lubrication. Use a lubricant made for marine toilets, or the one your toilet's manufacturer recommends. To reach the intake side, close the inlet seacock, disconnect the intake hose, pour a little lubricant in, reconnect and pump it through.
- Holding tank vent. Insects like to nest in vent fittings over winter, and a blocked vent can push odours back into the cabin.
Preventing calcium build-up
If your toilet flushes with seawater, scale is the most common cause of trouble. Minerals in seawater react with urine to form hard calcium deposits in the pump, valves and discharge hose. The toilet gets gradually harder to pump until it partially or fully blocks.
A monthly vinegar flush helps stop scale forming. Pour around 250 to 500 ml of white vinegar into the bowl and pump it slowly through, a stroke every few minutes, so it reaches the full length of the discharge hose. Then rinse well. Push it all the way through rather than leaving it in the bowl, as long soaks can swell and distort the joker valve.
Pumping a few litres of fresh water through before you leave the boat also slows scale formation. Check the anti-siphon valve while you're at it, as scale can make it stick. Most can be removed, soaked in warm water and cleaned.
If scale has already built up to the point where the toilet is hard to pump, vinegar won't shift it. Replacing the discharge hose is often the most reliable fix, and a marine plumber can advise on your system.
Smells and blockages
A smelly head is rarely the bowl itself. Wipe a damp cloth along the hoses and smell it. If the cloth smells, the hose has become permeated and needs replacing with odour-resistant sanitation hose.
Seawater left sitting in the system is another culprit. Tiny marine organisms die and produce a sulphur smell, which a freshwater flush before you leave largely solves. Small leaks at clamps or fittings, and holding tanks that aren't emptied and rinsed regularly, add to the problem.
For blockages, only human waste and marine-friendly toilet paper should go in. Wet wipes and household paper are common causes. A quick briefing for guests and kids before they use a manual toilet saves a lot of grief.
On smaller trailer boats, portable toilets need far less upkeep. Empty and rinse the waste tank after each trip, and check the seals before storing it.
Sewage discharge rules in New Zealand
National rules under the Resource Management (Marine Pollution) Regulations, summarised by Maritime NZ, say untreated sewage must not be discharged
- within 500 metres of land
- in water less than 5 metres deep
- within 500 metres of a marine farm or mātaitai (customary fishing reserve)
- within 200 metres of a marine reserve.
Regional councils can add further restrictions. In Auckland, untreated sewage cannot be discharged anywhere in the Waitematā or Mahurangi harbours, Bostaquet Bay on Kawau Island, or Port Fitzroy, Nagle Cove and Tryphena Harbour on Great Barrier Island. Auckland Council has the details. Northland Regional Council also offers a free app showing your position relative to the restricted areas in Northland and Auckland. Elsewhere, check your regional council's rules before you go.
In popular anchorages, a holding tank and a marina pump-out station are the simplest way to stay within the rules and keep your boating greener.
Why a small leak matters
Toilet seacocks and hoses sit below the waterline. If a hose splits or a clamp fails while the boat is unattended, water can come in for hours or days. Boats have sunk on their moorings from a toilet hose failure that started as a small weep. Knowing what to do if your boat starts sinking is worth a refresher too.
That's why the spring check matters, and why it pays to close the toilet seacocks whenever you leave the boat. A few minutes of maintenance now is far easier than dealing with a flooded cabin later.
Sources Maritime NZ, Auckland Council, Northland Regional Council