Here’s a Primer on Manual Marine Toilets.
Manual marine toilets that use a single piston pump all work the same. They may be laid out a little differently from brand to brand and model to model, but their principle and method of operation remain the same, be it a Jabsco, Wilcox-Crittenden, Raritan, RM69 from Holland, and any others you may run across.
The pumps are all oriented vertically, where you pump it straight up and down. Inside the pump cylinder is a double-acting piston. It is not a “plunger” - it is a piston. Double-acting means that a single piston accomplishes two different operations. The area inside the cylinder that is above the piston is used to draw in outside water to rinse the bowl. The area in the cylinder that is beneath the piston is used to draw the contents out of the toilet bowl and pump them off somewhere (to a holding tank, treatment system, or overboard).
Each pump has 4 check valves (one-way valves), two on the top half of the cylinder and two on the lower half of the cylinder. The check valves are used to direct the flow of water in only one direction.
On the intake half of the pump, either spring-loaded balls or weighted rubber flappers are used, to direct the flow of incoming water into and out of the top side of the pump, to supply rinse water to the toilet bowl. On the discharge side of the pump, a weighted rubber flapper valve is used, together with a joker valve (also called a duckbill valve), to draw some of the contents out of the toilet bowl, and pump it off to the ultimate destination (holding tank, treatment system or overboard).
The most common problem that arises, other than various pump leaks which are usually minor and won’t be addressed here, is that the toilet doesn’t want to pump the contents out of the toilet bowl. Here’s how the discharge half of the pump works: On the upstroke of the piston, a vacuum is created in the area beneath the piston. This causes the joker valve to close tightly, and the flapper valve beneath the pump to open, allowing some of the contents of the toilet bowl to be drawn into the bottom half of the pump. Then, on the down stroke of the piston, the flapper valve is slammed shut, and the effluent is forced out of the bottom of the pump, through the joker valve, and off down the line.
Now, when it doesn’t want to pump out, the joker valve nearly always needs to be replaced. Note: the joker valve should be changed every other year, as a matter of preventive maintenance. What happens is that dissolved minerals that are in the water, settle out during periods of non-use, and build up on the joker valve, making it hard and causing it to lose its flexibility. When this happens, it can’t seal tightly on the upstroke of the piston, and no vacuum is generated when you pump it. The water simply moves up and down a bit, but doesn’t go anywhere. Sometimes the flapper valve needs to be replaced too, but 80+ percent of the time, simply replacing the joker valve will solve the problem.
The joker valve also serves a second function; it acts as a check valve to stop backflow from returning to the toilet when there’s a partial clog somewhere down the line, or if you must pump upward to a vented loop fitting. If the joker valve can’t seal tightly, two problems arise; 1) the toilet won’t empty the bowl, and 2) you may get backflow into the bowl. Joker valves generally, are self-cleaning. So if you get a wad of toilet paper caught in it, or a cigarette filter caught in it, it will usually work free within a little time. But if it has a mineral buildup on it, or if it has been attacked and deformed from detergents or other non-recommended cleaning and deodorizing products, the only cure will be to replace it. The joker valve is the single most-crucial consumable part in a manual toilet, and definitely needs to be replaced at or before the manufacturer’s recommended intervals.
Other problems that can arise are that the toilet won’t draw in outside water to rinse the bowl. This can be caused by: 1) Marine vegetation or other detritus (tiny mussels, minnows, jellyfish, et al) was drawn into the toilet, along with the incoming water, and is stopping the check valves in the top half of the pump from sealing tightly. This necessitates that the appropriate area of the pump be disassembled and the check valves, and their seats, cleaned. It may be necessary to replace the check valves, depending on their condition. 2) A worn out “O” ring on the piston. If the “O” ring is worn out, the overall efficiency of the toilet will drop, and it may not generate enough suction to draw in outside water, to send to the toilet bowl for rinsing purposes. If it becomes worn enough, you can actually get bypass from one side of the piston to the other, and you may begin recycling “dirty” water through the toilet, and will see it coming out the drain holes on the underside of the top rim of the toilet bowl.
This (bypass from one side of the piston to the other) is the reason a manual toilet MUST NEVER be connected to any source of water that you may also drink or wash yourself, your clothing, your food, or your dishes, pots and pans with. Bypass can occur within the pump, to re-circulate the water from the “dirty” side of the pump to the clean side of the pump due to the piston “O” ring not sealing tightly within the pump cylinder. You’d be taking a helluva risk of contaminating your water source. The piston “O” ring NEVER seals tightly enough inside the cylinder to stop bacteria from crossing over; not even in a brand-new pump. If you want a manual toilet to flush with fresh water, rather than raw water, install another, dedicated, tank that WILL ONLY be used for the toilet, then when the tank is empty, refill it as needed.
Manual marine toilets that use a single piston pump all work the same. They may be laid out a little differently from brand to brand and model to model, but their principle and method of operation remain the same, be it a Jabsco, Wilcox-Crittenden, Raritan, RM69 from Holland, and any others you may run across.
The pumps are all oriented vertically, where you pump it straight up and down. Inside the pump cylinder is a double-acting piston. It is not a “plunger” - it is a piston. Double-acting means that a single piston accomplishes two different operations. The area inside the cylinder that is above the piston is used to draw in outside water to rinse the bowl. The area in the cylinder that is beneath the piston is used to draw the contents out of the toilet bowl and pump them off somewhere (to a holding tank, treatment system, or overboard).
Each pump has 4 check valves (one-way valves), two on the top half of the cylinder and two on the lower half of the cylinder. The check valves are used to direct the flow of water in only one direction.
On the intake half of the pump, either spring-loaded balls or weighted rubber flappers are used, to direct the flow of incoming water into and out of the top side of the pump, to supply rinse water to the toilet bowl. On the discharge side of the pump, a weighted rubber flapper valve is used, together with a joker valve (also called a duckbill valve), to draw some of the contents out of the toilet bowl, and pump it off to the ultimate destination (holding tank, treatment system or overboard).
The most common problem that arises, other than various pump leaks which are usually minor and won’t be addressed here, is that the toilet doesn’t want to pump the contents out of the toilet bowl. Here’s how the discharge half of the pump works: On the upstroke of the piston, a vacuum is created in the area beneath the piston. This causes the joker valve to close tightly, and the flapper valve beneath the pump to open, allowing some of the contents of the toilet bowl to be drawn into the bottom half of the pump. Then, on the down stroke of the piston, the flapper valve is slammed shut, and the effluent is forced out of the bottom of the pump, through the joker valve, and off down the line.
Now, when it doesn’t want to pump out, the joker valve nearly always needs to be replaced. Note: the joker valve should be changed every other year, as a matter of preventive maintenance. What happens is that dissolved minerals that are in the water, settle out during periods of non-use, and build up on the joker valve, making it hard and causing it to lose its flexibility. When this happens, it can’t seal tightly on the upstroke of the piston, and no vacuum is generated when you pump it. The water simply moves up and down a bit, but doesn’t go anywhere. Sometimes the flapper valve needs to be replaced too, but 80+ percent of the time, simply replacing the joker valve will solve the problem.
The joker valve also serves a second function; it acts as a check valve to stop backflow from returning to the toilet when there’s a partial clog somewhere down the line, or if you must pump upward to a vented loop fitting. If the joker valve can’t seal tightly, two problems arise; 1) the toilet won’t empty the bowl, and 2) you may get backflow into the bowl. Joker valves generally, are self-cleaning. So if you get a wad of toilet paper caught in it, or a cigarette filter caught in it, it will usually work free within a little time. But if it has a mineral buildup on it, or if it has been attacked and deformed from detergents or other non-recommended cleaning and deodorizing products, the only cure will be to replace it. The joker valve is the single most-crucial consumable part in a manual toilet, and definitely needs to be replaced at or before the manufacturer’s recommended intervals.
Other problems that can arise are that the toilet won’t draw in outside water to rinse the bowl. This can be caused by: 1) Marine vegetation or other detritus (tiny mussels, minnows, jellyfish, et al) was drawn into the toilet, along with the incoming water, and is stopping the check valves in the top half of the pump from sealing tightly. This necessitates that the appropriate area of the pump be disassembled and the check valves, and their seats, cleaned. It may be necessary to replace the check valves, depending on their condition. 2) A worn out “O” ring on the piston. If the “O” ring is worn out, the overall efficiency of the toilet will drop, and it may not generate enough suction to draw in outside water, to send to the toilet bowl for rinsing purposes. If it becomes worn enough, you can actually get bypass from one side of the piston to the other, and you may begin recycling “dirty” water through the toilet, and will see it coming out the drain holes on the underside of the top rim of the toilet bowl.
This (bypass from one side of the piston to the other) is the reason a manual toilet MUST NEVER be connected to any source of water that you may also drink or wash yourself, your clothing, your food, or your dishes, pots and pans with. Bypass can occur within the pump, to re-circulate the water from the “dirty” side of the pump to the clean side of the pump due to the piston “O” ring not sealing tightly within the pump cylinder. You’d be taking a helluva risk of contaminating your water source. The piston “O” ring NEVER seals tightly enough inside the cylinder to stop bacteria from crossing over; not even in a brand-new pump. If you want a manual toilet to flush with fresh water, rather than raw water, install another, dedicated, tank that WILL ONLY be used for the toilet, then when the tank is empty, refill it as needed.
