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In this section I will disscuss some common plumbing subjects and try to enlighten you on some of the types of toilets,  valves,   and pumps. I recommend reading this whole section but you can use the links to quickly access information.

Marine toilets

Winterizing toilets

Water pumps

Engine cooling pumps


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 Marine tiolets

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Marine sanitation devices (MSD's) in US vessels less than 65' must conform to one of three main types.

Type 1)These chemically treat and break up raw sewage so when discharged overboard no floating solids or bacteria remain.

Type 2)These are similar to type one's but teat sewage to higher standards.

Type 3)These are the most common systems and the only one I will get into in this chapter.They include portable toilets and toilets that store sewage in a holding tank on board.The tank can be emptied at a dockside pump out facility or beyond the 3 mile from shore limit.It is legal to have a Y valve fitted so you can choose to pump overboard or to the holding tank.If you are within the 3 mile limit you must the valve must be locked in the holding tank position.This can be done by either removing the handle, padlocking or even a ziptie will do the trick.

Vented Loops

When installing any marine toilet that is below the waterline you must install vented loops in the inlet and discharge hoses.The purpose of the vented loops is to break any effort to reverse syphon water or waste back into th toilet.This has been a very common cause of boats sinking.

On a powerboat you want the vented loops to be a minimum of 12'' above the waterline.

To stop odour run a small hose from the top of the discharge vented loop to a vent fitting on the hull of the boat.Ensure it is positioned slightly higher than the vented loop.

On a sailboat we are aiming to get the vented loops as close as we can to 6" to 8" above the maximum heeled over waterline.

Use good quality sanitation hose for both inlet and outlet hoses and good quality vented loops.Use good quality stainless steel hose clamps and double clamp every connection that is below the waterline.

Routine Maintenance

To help keep clean occasionally put some biodegradable laundry soap in about 1/2 bowl of warm water and flush through system.Then 1/2 fill bowl again with warm water and add a little mineral or baby oil and pump through.This will help keep all the rubber valves and seals in good condition.It's also a good idea to go round and inspect the vented loops and make sure the are clean and in good condition.Also visually inspect all hose clamps.

Another problem is calcium build up.If it's not bad try flushing some vinegar through the system once a month to keep the build up from forming.If it's bad a Muriatic Acid treatment may be necessary.You can usually get it at the hardware store.It will disolve calcium but will also attack metal parts although at a very slow rate.Fill the bowl with a 10% mixture of muriatic acid and water (10% muriatic + 90%water).Observe any warnings on the bottle.Let stand in bowl untill almost all fizzing has stopped.Then pump the bowl almost empty so now the mixture is in the pump body.Wait a few minutes then pump a couple more times to move the mixture into the discharge hose.Again wait a few minutes then pump all the mixture overboard and flush with plenty of water.In severe cases several treatments maybe necessary. If this still wont allow system to operate smoothly you will have to disassemble the toilet any manually remove calcium from the parts.Banging the hoses on the dock will usually break the calcium out of them but I would recommend replacing them.

Electric Toilets

There are a three types of these toilets which are the most common.

One uses an electric motor to automatically operate the top of a piston type pump.This is a nice design because you can disconnect the electric motor push rod and then manually pump it if necessary.(Raritan makes one such model)

Another model uses an electric pump to do several jobs.First it has an inlet pump section to pump flushing water to the bowl.Second ,the pump also has a section which pumps out waste while breaking it down also.These pumps work well but have the disadvantage of being electric only.

My personal favourite is the Lavac toilet because of its duribilty and simplicity.The lid has an air tight seal so when the diapham discharge pump is pumped it creats a vacuum in the bowl.This serves two purpose's. 1)Removes waste from the bowl. 2)The suction created brings in flushing water.These are very reliable and robust systems.The system I like best uses an electric diapham pump in line with a backup manual pump.

Macerator pumps

Macerator pumps are primarily used to break up and pump out the waste from holding tanks.They are similar to electric toilet pumps except there is no flushing pump built into them.


Winterizing toilet system's

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Not winterizing toilets is quite a common reason for toilet failure.Here are some steps to prevent that.

1)Pump bowl dry and go get holding tank pumped out.

2)Get a gallon of propelene glycol *(Do not use ethlylene glycol)*

3)Shut off tiolet water inlet valve( seacock). Remove hose from seacock and put into the bottle of propylene glycol.

4)Switch to flush and flush 2/3 of gallon through system to holding tank.

5)Switch to overboard discharge and pump remainder of gallon out of discharge hose. I like to leave a couple inches left standing in the bowl.

6)Connect inlet hose back onto seacock but leave it in closed position.Also switch selecter switch back to holding tank and legally secure again.

Type 1or 2(MSD's)

If you have one of these systems please check with manufacturer for safe winterization procedures.


Be smart and keep a "head" of possible toilet problems.Have fun.


Water pumps

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There are several types of pumps which are common on boats .You can read about them all or click the link to read on a particular pump.Also there is some advice on how to choose a pump for certain jobs.

Electric pumps

1)Variable volume impeller pumps (most common)

2)Positive displacement pumps.

3)Centrifugal pumps.

Manual pumps

1)Diapham pumps

2)Piston pumps

Engine cooling pumps

Choosing a pump

Variable volume impeller pumps

There are three common styles of this pump.

A)The most common is the flexible impeller pump which uses a flexible impeller turning in a pump body .

B)The vane pump which uses hard material vanes which slide in and out slots as pump impeller turns.

C)Rotary pumps which are a little complicated to describe but are good pumps.(not that common though)

Positive displacement pumps

These pumps work by an electric motor moving a diaphram up and down.When moving up it will draw fluid into the pump chamber through the inlet valve.When pushing down the inlet valve will close so the fluid will be pushed out the outlet valve.

Centrifugal pumps

These pumps are mostly used for bilge pumps and livewell pumps and sometimes washdown systems.They have the advantage of no moving parts in contact with the pump housing and good quality ones can run dry indefinitly without damage.The down side is they will not self prime and they will not push fluid very high.

Continuous Duty Pumps

Another thing to consider is if you intend to regularly use the pump for more than 4 or 5 minutes at a time you should invest in a continuous duty pump.(except centrifugal pumps which are already continuous duty).

Manual pumps

There are two common types of manual pumps used on boats.

A)Piston pumps.

B)Diaphram pumps.

Piston pumps

These use a cylinder with a piston in it.With the use of a one way valve in the base of the cylinder and a one way valve in the sliding piston these pumps can pull water to them and pump out the outlet.They are commonly used in the galley to draw water from the tanks.They are also used to draw oil out of the engine for oil changes.Either through the dipstick hole or the bottom of the sump.If you have just pumped oil it pays to pump some warm soapy water through the pump after use to help preserve the seals in the pump.One of my favourites is the "Little Pal" from Jabsco.If you buy a piston pump it's worth picking up a couple rebuild kits to last over the years.If you can't get the kits I wouldn't get the pump.

Diapham pumps

If you want a really good manual water pump either in the galley or for emergency water removal these pumps can't be beat.The big pumps can remove a lot of water fast and are extremely durable and reliable and can be easily rebuilt if necessary.For galley use they make some great foot operated models which allow your hands to be free for washing dishes etc.Again if you get any pump also purchase a couple of rebuild kits even though it will probably be years before you will need them.

Engine cooling pumps

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The majority of engine cooling pumps are engine driven impeller pumps.I recommend referring to your engine manual for appropriate maintenance and overhaul of your pump.Generally I recomend you inspect your pump impeller annually.Usually to do this you remove the front plate carefully from the pump.If you damage the gasket replace it with one of the same thickness.Likewise if it's an O ring.If too thick of a gasket water will pass around the end of the impeller and you will lose performance.If you have too little thickness you will have extra friction which could cause pump failure.

Once the end plate is off on most pumps you can draw out the impeller with needle nose pliers.If this is not possible it may be that it is keyed to the shaft with a locking screw.If so you will have to try to get side access to it through one of the ports.If this is not an option you may have to remove the pump and tap the shaft out with the impeller still attached.

Once removed inspect the impeller for flexibility and wear.If there is any doubt replace the impeller.Also check the condition of the front plate for excessive scoring.Sometimes if you have a badly scored front plate you clean up the outside surface and assemble it as the inside surface.This is only to get you out of a tight spot.First chance you get you should replace it with a new plate.Reassemble with a light coating of petroleum jelly or a teflon based waterproof grease.Sometimes it's hard to get the impeller back into the housing.I've had luck using a hose clamp to help squish the blades in enough to get them started into the housing.Position the clamp about 1/4'' in from the leading end of the impeller you are trying to install.Good Luck.



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Types of Valves(seacocks)

1) Traditional tapered plug bronze seacocks.

This type uses a tapered plug fitting into a tapered body.The plug is hollow with an opening in the plug that when lined up with the opening in the valve body will allow water to flow.It takes a 1/4 turn to go from on to off.It is open when the handle is lined up with the tailpiece and closed when at 90 degree's to the tailpiece.Ideally these should be dissassembled and greased every year or at least every haulout for boats normally in the water.If the plug has wear and starts to leak first we try to fix it with grinding paste(usually found at the autoparts store). Pull plug out and smear paste on the seating surface.Put plug into body and work round and round.Wipe away and inspect.You are looking to see smooth even surface to surface wear ,keep repeating till you do.When happy that it's good wipe all paste off , regrease and assemble.If this doesn't work replacement of valve may be necessary.

Rubber plug seacocks

These are similar to our traditional style but use a rubber plug with a metal lined hole in the center.These should also be greased annually if possible.Tighten just untill water stops dripping as you can easily deform the rubber plug.If the plug is already deformed you can try filing off the deformaties off with a large flat file or with "CAREFULL" use of a belt sander.It's worth a try before replacement.

Ball Valves

Ball valves are efficient and foolproof.You can get metal versions and plastic versions.They should also be annually greased if possible.The plastic versions have a couple downsides.

A) They could melt in a fire.

B)In time the plastic could get brittle and snap if decent pressure is applied.

But one BIG advantage is that they are not subject to galvanic corrosion which may be an out weighing plus in some marina's.

Gate Valves

I you have any gate valves on the boat get rid of them as soon as possible.They have not place on a boat in regards to a seacock.Check figure below for what they look like.I've had too many bad experiences with these valves to ever trust them.


If your valves are not turning you on they should be.Have fun Boatcando guy.