Plumbing Aboard a Boat: the Differences

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How Boat Plumbing Differs

Boat plumbing differs from household plumbing, and even to some extent from that aboard an RV. Many articles have been written about plumbing in a house with regard to fixing problems and general maintenance, and a few have addressed the RV'ers.

Boats, however, are yet another "animal." Aboard a boat large enough to have cooking, bathing and toilet facilities, there are 3 different ways the plumbing is handled and routed, and 3 different ways used for dealing with waste water.

Fresh Water Storage Tank

The first storage tank I will address is the freshwater tank. This is filled only with potable (drinkable) water from a city water supply or well. Some may argue that since most don't drink the water from the faucet on a boat, as it is mainly used for washing, it doesn't matter. However, do you want to wash your dishes in water unsafe to drink? I don't.

Depending on the size of the boat, this tank can range from 20 gallons (what we had on our boat), upwards to extreme limits. Large cruise ships may have freshwater tanks holding thousands of gallons. I don't know for certain, but I'm guessing it is possible that these days, some of the largest ships may have on-board de-salinization plants to create fresh water as needed.

Again, depending on the size of the boat, the tank, and level of luxury, there may or may not be a gauge indicating the level of the water left.

A seacock will generally be this type of valve on smaller yachts and pleasure boats Shown in closed position
A seacock will generally be this type of valve on smaller yachts and pleasure boats Shown in closed position | Source

Water From Another Source

On a boat, only the sink(s) and shower draw from the freshwater tank. The toilet uses a device called a sea-cock. This is a special valve that draws water in directly from the water in which you are boating.

The sea-cock has a built-in mesh filter to prevent drawing in debris that could foul the pipes or add unnecessary burden to the holding tank.

The sea-cock must be checked on a very regular basis for proper operation, and the valve must be able to turn easily. If it is frozen, have it replaced. Each time you return from your trip, be sure to close it.

Because this is a direct line to the water in which the boat sits, it holds a potential for disaster. Boats have sunk due to being flooded by a faulty sea-cock. Even though, like a faucet in your home, the water in an open sea-cock valve is not supposed to begin flowing until there is a demand (i.e. flushing the toilet), things can break or wear out.

Can you imagine the nasty mess of finding your boat riding up to the gunwales in water, awash not only in sea or river water, but also the upwelling contents of the holding tank? If you have a small leak, the bilge pumps may handle it--for a while, but if there is a major malfunction, they will not be able to keep up.

The sea-cock and bilge pumps are the single most important pieces of plumbing equipment to have in good working order.

Gray Water Holding

On most pleasure craft, gray water is handled in two ways. I'm going by what was on our boat, but it was probably fairly typical of small yachts.

The water from the sink was routed directly overboard through a small port right behind the sink. The drainage from the sink had the standard P-trap underneath, just as is found in homes and RV's, but instead of connecting to a sewer line or routing into the holding tank, it simply went out the side of the boat and into whatever body of water you were cruising.

Gray water is not harmful, and on board a boat, you are required to use specifically made biodegradable soaps and detergents for this very reason. That way, it breaks down easily and does not harm wildlife.

The shower is similar, but handled in a slightly different way. On many smaller yachts (30 feet or so), the shower is positioned right above the toilet. When using it, you must be sure the toilet lid is closed, so you do not prematurely fill up your black water holding tank.

The shower drain in the floor routes the water back into the bilge where the bilge pumps pick it up and toss it overboard. Like the sink, then, the shower water goes out to the body of water, but via a different means.

Typical Pump-Out Station

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Black Water Tank--the Ugly Stuff

The holding tank from the toilet is separate from everything else. For obvious health reasons, it is illegal to dump black water overboard.

However, on the water, you cannot simply pull up to a dump station, open a valve, and use gravity to dump contents via a hose into the land-based holding tank.

Instead, there are docks with pumping stations. In the majority of cases, this is strictly a do-it-yourself operation. The pump-out station operators may offer help or instructions for newbies, but you are bascially on your own.

You pull up dockside, and attach the screw-in hose from their pump to your pump-out port. Next, you pull in a freshwater hose through the porthole (that's a window for non-boating folks) and aim it down the toilet. Turn on the water, and turn on the pump. The pump-out hose is often a clear material, and you can see when it is no longer pumping out waste but clear water. If the hose is opaque, listen for a change in the pitch of the pump that will tell you it's done. Turn off the water, and pump a little more, so your tank is not full of water.

Disconnect the pump-out hose, replace the cap on the pump-out port. The toilet uses chemicals as in an RV, to both help break down solids and control odor; at this point, refill the chemical into the holding tank via the toilet, as per the dosage directions on the bottle. All done!

Some areas provide free pump-out service; others charge a fee.

For More Information

Know Your Boat : The Guide to Everything That Makes Your Boat Work
Know Your Boat : The Guide to Everything That Makes Your Boat Work

Comprehensive yet simple handbook for all the basics of boat maintenance, not just the plumbing.

 

Maintenance of Boat Plumbing

More than any other situation, maintaining everything in good working order aboard a boat is vital. Even in an RV, you can drive to a repair shop. Not so with a boat.

Plumbers don't make calls out on the water. Nothing, but nothing would be more maddening, inconventient, and possibly dangerous than to be stuck out in the middle of a remote waterway with plumbing problems.

Check all systems for proper operation each time you use your boat, and nip any problems in the bud. Make sure you schedule maintenance days, where you can go over everything with no rush to get underway, and you will have many happy and trouble-free times out on the water.

© 2011 DzyMsLizzy

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Comments 10 comments

K9keystrokes profile image

K9keystrokes 5 years ago from Northern, California

What a great hub! You are spot on with one DML! Our boat had full facilities and it can be trouble if you don't know how to manage it. We were fortunate to have a brother who is very savvy at everything having to with a boat, inside and out. Nothing is worst than not having boat plumbing know-how when it comes to playing on the water! Nautical plumbing, as you say, IS a whole other animal! Up and all across the board!

HubHugs~

K9


WillStarr profile image

WillStarr 5 years ago from Phoenix, Arizona

Informative Hub!


DzyMsLizzy profile image

DzyMsLizzy 5 years ago from Oakley, CA Author

@K9--thanks so much for all the votes and great comment. I kind of miss our boat--and kind of not. The downside was, it amounted to taking all the housework with you at playtime. We sold it a few years back, after it sat most of the year without being used, and no extra money for the inflated gas-dock prices--why keep paying slip fees?

@Will Starr..thank you very much! Glad you liked the article.


PenMePretty 5 years ago from Franklin

With all your knowledge...I want you to be on the boat with me. please. VOTED up, interesting, useful.


DzyMsLizzy profile image

DzyMsLizzy 5 years ago from Oakley, CA Author

Hello, PenMePretty!

Thanks so much for your kind comment and the votes! Come back any time.

Cheers!


Simone Smith profile image

Simone Smith 5 years ago from San Francisco

I've been curious about this for ages, so I really enjoyed reading this Hub! The black water tank... gosh... blehhh... but it's smart that they've got it separated out. Goodness, it's fascinating how boats work. Thanks for sharing the fab explanation!


Robin profile image

Robin 5 years ago from San Francisco

Very interesting! I always wondered how this was done. I think we'll just stick to speed boats where there isn't a bathroom; I'm not good at plumbing issues in the house, so a boat's plumbing would really be difficult! Thanks for the informative Hub!


DzyMsLizzy profile image

DzyMsLizzy 5 years ago from Oakley, CA Author

@ Simone- Hi there! Thanks so much. Nice to know I was able to provide useful info...appreciate the comment!

@Robin- Hello! Thanks so much for stopping by and leaving a comment. ... LOL.. lack of a place to 'go' would be my main problem with a speedboat. I'm not into trying to sit on a coffee can or hanging over the side. ;-)

... As long as everything is taken care of, problems don't normally happen. Glad you found the article interesting.


poetryman6969 profile image

poetryman6969 22 months ago

It confirms my impression that boats are for other folks but interesting nonetheless!


DzyMsLizzy profile image

DzyMsLizzy 22 months ago from Oakley, CA Author

Hello, poetryman6969,

LOL! True, not everyone is "boat-minded." I do miss our boat; it was fun, but the old saying of "a boat is a hole in the water surrounded by wood (or fiberglass, these days), into which you pour money" was pretty true.

Even normal maintenance parts, once you put "marine" in front of the name of the part, the price goes way up. Then, the docking fees, if your boat, (like ours was), is too big to trailer, and the inflated prices for fuel at the gas docks. It all adds up.

On the other side of the coin from your comment is the fact that there are plenty of people who have boats, and who should not. There are many idiots driving about on the water, just as they do on the road. Just because you can afford a boat, does not mean you should buy one, in those cases!

Thanks much for stopping by; I'm pleased you enjoyed the article.

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