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Houseboat Plumbing - installation of sink drains and thru hull fittings?

by David V
(Cincinnati, Ohio)

Houseboat Plumbing - sink drains and thru hull fittings.

Houseboat Plumbing - sink drains and thru hull fittings.

Looking at houseboat plumbing, and have questions about installations of thru hull fitting and drains for the sinks? I need to replace two thru hull fittings that drain my sinks.

Any tips on installing the thru hull fittings in an aluminum hull, and should the pipe draining the sink run down and out or have a upward flow to provide a water trap?

Thanks, Dave in Cincinnati

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Reply - Answer
Well Dave, you have a good question about different houseboat plumbing installations.

When it comes to the thru hull fittings, you can use either brass or the plastic fittings if it's above the waterline. Try to have the fitting located high enough up on the hull as to not take on water when traveling in rough water or waves.

There is different ways to run the drain pipes for sinks, depending on whether you're dumping overboard, into a grey water holding tank, or directly downward through a thru hull fitting in the hull.

If you're going through the sidewall, you can route the drain pipe or hose directly to the thru hull without an "upward loop" water trap.

I've seen a houseboat that had a two-way valve to allow it to either drain the sinks into a gray water holding tank, or directly through the bottom of the hull, and those sinks had a water trap (upward loop).

Lastly, hopefully some of our readers will share and post comments about their houseboat plumbing, sink drains, or thru hull experiences. Feel free to use the "Click here to post comments." link found near the bottom of this page.

Thanks again for sharing, IAN from all-about-houseboats

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Comments for Houseboat Plumbing - installation of sink drains and thru hull fittings?

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by: Amsterdamhouseboats

Don't use any metal through fittings on an aluminum hull, unless they are specially made for an aluminum boat.

Especially under the waterline, you can get dangerous electrolytic corrosion around the fitting, until it just pops out [and you sink].

There are marine grade super strong plastic through hull [sea valve] fittings just for this.

If draining a sink through the hull below the waterline [sneaky of you], you'll need to T in an air vent into the down pipe a few inches above the waterline, or it will get an airlock and won't drain.

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