Electric Marine Toilet Troubleshooting: Won't Flush, Weak Flush, Won't Stop Filling

Turn off the toilet breaker and, on freshwater models, the water pump. Find both seacocks (intake for raw-water models, and the discharge if it can go overboard) and make sure they work. Put down rags and have a bucket and trash bags ready. Tell everyone aboard not to use the head.

Check the simple things first:

• Is the breaker or fuse for the toilet on and intact? Is the battery switch on and the house battery charged?
• Does the control panel light up, or show a fault or "tank full" warning? Some controls connect to a holding-tank sensor; Raritan's Smart Toilet Control can warn when the tank is full. Pump out and try again.
• Measure voltage at the toilet's motor or control box while someone presses the button. No voltage means the problem is in the wiring, breaker or control, not the toilet.

Low voltage is a common cause. Raritan notes that its older electric heads were very voltage-sensitive: a weak battery or corroded joints made them run slowly and not discharge properly. Measure the voltage at the toilet while it runs and compare with the battery. A big drop means corroded terminals, a tired breaker or undersized wire; clean and tighten connections or call a marine electrician. Charge the batteries or run the charger and test again.

That usually means the macerator or pump is jammed. A stalled motor draws high current and trips the breaker. Common causes are wipes, paper towels, feminine products, hair or a foreign object, or salt and scale left from a raw-water toilet that sat dry. With the breaker off and seacocks closed:

• Don't keep resetting the breaker; you can burn out the motor or wiring.
• Follow your manual to open the pump or macerator housing, or to turn the motor shaft by hand if your model allows it, and remove the jam.
• Check for a damaged blade or impeller while it's open.

If it still trips with nothing jammed, the motor or wiring may be failing; call a pro.

Raritan's checklist: make sure the intake seacock is fully open, the through-hull isn't clogged (barnacles, weed) and the intake strainer, if fitted, is clean. Then check the intake pump: on some models a check ball can stick, and a rubber impeller can take a "set" (vanes bent one way) or be damaged from running dry. Replace a set impeller. Practical Sailor notes that air in the intake line hurts pump performance, which is why some raw-water electric heads use a small solenoid to close the intake's vented loop during the flush; if that solenoid sticks open, the pump can lose suction.

Check that the freshwater pump is on, the tank isn't empty and other faucets have good pressure (see the freshwater pump guide). If the rest of the boat has water but the toilet doesn't, the rinse solenoid valve may be stuck closed, blocked with debris or not getting power.

On a freshwater model, Xylem (Jabsco) says fresh water that keeps rising into the bowl from the rim when nobody is using the toilet usually means debris is holding the rinse solenoid valve open. The fix is to turn off the water pump and power, take the valve apart as the maker shows, clean the diaphragm and seat, and reassemble without losing the small spring and plunger. If cleaning doesn't stop it, replace the valve with the one for your model and voltage. Note Xylem's distinction: water coming up from the bottom of the bowl is a different problem (steps 8 and 9).

On a raw-water model, water that keeps coming in on its own is siphoning through the intake. Close the intake seacock now, then check the intake's vented loop (step 9).

Raritan says the most common cause of waste water flowing back into the bowl after a flush is a worn joker valve. Joker valves stiffen and scale up with age. Replace it with the part for your exact model (some models use two, which should be replaced together). The manual head rebuild guide shows the general idea of working on the discharge side. If the bowl refills from the bottom while the boat is in the water and the discharge goes overboard, siphoning through the discharge line is also possible: close the discharge seacock and check the vented loop.

Raritan explains that its toilets aren't designed to hold water in the bowl unless a vented loop is installed in the discharge line, with the top of the loop generally about 4 inches above the top of the bowl (check your installation manual for the exact height). If a loop is installed but the bowl still empties, the loop's vent is probably clogged, letting water siphon out. Practical Sailor stresses that raw-water intake and discharge lines need vented loops that stay above the waterline at all angles of heel. The small vent valve at the top of each loop clogs with salt and scale over time and needs cleaning or replacing; the vented loop guide shows how.

The telltale sign: in Xylem's Jabsco demonstration, a blocked discharge makes the water swirl around and around in the bowl while the pump runs, because it has nowhere to go. That points to the discharge side: the joker valve, the hose or something past it.

Raritan's test isolates the toilet: with the breaker off and discharge seacock closed (if any), disconnect the discharge hose at the toilet, attach a short spare hose and lead it into a bucket. Restore power and flush.

• Flushes well into the bucket: the toilet is fine; the blockage is in the sanitation hose, Y-valve, vented loop, holding tank vent line or seacock.
• Still flushes poorly: the problem is in the toilet itself (pump, macerator, joker valve); go back to steps 3, 4 and 8. Xylem says waste still swirling in the bowl during this test usually means a clogged joker valve in the discharge elbow.

Empty the bucket at a pump-out or shore toilet, never overboard in restricted waters.

Old sanitation hose builds up hard scale inside that narrows it, especially in raw-water systems. A blocked holding-tank vent makes the tank resist incoming flow, so the toilet struggles and the tank can smell or even burp waste. Check:

• The holding-tank vent line and its filter (see the vent filter guide).
• The Y-valve: does it turn fully, and is it set to the tank?
• The hose: squeeze it and look for scale; descale it or replace it (see the sanitation hose descaling and head hose replacement guides). For light buildup, Jabsco's technicians suggest letting a couple of cups of white vinegar sit in the discharge hose overnight and then flushing it through with water; check that your own toilet maker allows vinegar first.
• Spiders, insects and debris in the holding-tank vent fitting outside the hull. Jabsco says it sees blocked vents often, especially behind overflowing tanks.

Use only cleaners your toilet maker approves. Xylem warns that bleach, drain cleaners and harsh deodorizers degrade rubber seals and joker valves, sometimes within one season.

If the bowl overfills with seawater when you're running fast, Raritan says the most common cause is the intake through-hull scoop facing forward and forcing water in. Reversing the scoop usually fixes it. A properly placed vented loop on the intake also helps. Keep the intake seacock closed when the toilet isn't in use if you're unsure.

Raritan notes that on raw-water toilets, sea life and weed trapped in the rim and intake line die and give off a sulfur smell when the head sits. Flushing with fresh water before you leave the boat helps; some owners convert to freshwater flush. A sewage smell (not rotten eggs) usually comes from permeated hoses, a tank or vent problem; see the holding tank and hose guides.

• Only human waste and marine-safe toilet paper go in. Wipes, paper towels and feminine products go in the trash.
• Flush enough water to clear the hose to the tank each time.
• Before leaving the boat for a while, flush through with fresh water so salt and scale don't dry in the pump.
• Winterize with non-toxic propylene glycol antifreeze only. Xylem warns against alcohol-blend "RV antifreeze" (it swells rubber) and against petroleum or vegetable oils on rubber parts. Run it until antifreeze reaches the end of the discharge line, and don't forget the intake hose from the seacock. If the toilet feeds an onboard treatment system (a Type I MSD such as Raritan's Electro Scan or Purasan), check its manual first: Raritan says antifreeze must not go into its treatment systems, which are winterized dry.