# Plumbing sink drain to head intake



## CLucas (Feb 10, 2007)

Having done some research, I'm convinced of the benefits of plumbing my head sink drain to my head intake, allowing me to flush using fresh water and avoid the stink of dying sea critters, etc. I don't think I'm missing anything here (pretty straightforward), but the below diagram is how I'll be proceeding. My only question is whether I need another diverter valve where the sink drain Ts into the head intake line -- don't think so, but am putting it out there.


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## sailingdog (Mar 19, 2006)

Clucas—

The simplest way to do this is to eliminate the sink drain seacock and diverter valve at the sink. There's no reason you can't drain the sink through the head intake seacock. If you want to flush the sink using fresh water from the head, just close the seacock. This is actually the method suggested by Peggie Hall, diva of marine heads and plumbing. 

That said, what you've drawn is basically how my head sink is setup, excep there's no seacock on the sink drain, since it drains above the waterline, by about two feet, and there's little risk of heeling to submerse it on a trimaran.


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## CLucas (Feb 10, 2007)

sailingdog said:


> Clucas-
> 
> The simplest way to do this is to eliminate the sink drain seacock and diverter valve at the sink. There's no reason you can't drain the sink through the head intake seacock. If you want to flush the sink using fresh water from the head, just close the seacock. This is actually the method suggested by Peggie Hall, diva of marine heads and plumbing.


I think you responded within about 90 seconds -- make that 60... 

Your suggestion (and Peggie's) is even simpler, except that... 
a) the head intake seacock is under the vberth and access requires either lifting cushions and an access panel or pulling out a drawer and reaching a long way (if it's even reachable). I've updated the image to indicate the forward bulkhead between the head sink and head intake. As it is in the diagram, I can leave the head intake seacock closed (so long I want to flush using fresh water). I routinely close all my seacocks (except cockpit drains) when we leave the boat.

b) Removing the sink drain seacock turns this into a much bigger project if I wanted to remove the thru-hull. I suppose I could just cap off the seacock... Ironically, I actually just replaced it last year -- completely seized (open!) and badly corroded.


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## christyleigh (Dec 17, 2001)

I did essentially what you are considering on my previous C28 and C320. I basically made the plumbing into an *H *with the left vertical being the salt water to head, and the right vertical being the sink drain to outlet. I added the horizontal line being the tee'd connection between the existing lines with an On/Off valve in the middle of the horizontal line of the *H*.
Now on my Nauticat even though I have a separate shower stall and faucet I also have a (second) hand-held shower type faucet at the sink which is right next to the head bowl. Now I just use that hand-held to add, and more importantly Pressure Spray, the exact amount of water I need to clean things up. My point is if you have a shower head fixture, as many boats do, within reach of your head bowl I have found that to work much better than simply to have it flooded with fresh water.


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## sailingdog (Mar 19, 2006)

In that case, carry on... should work just fine... it does on my boat. Makes winterizing the head a cinch. 



CLucas said:


> I think you responded within about 90 seconds -- make that 60...
> 
> Your suggestion (and Peggie's) is even simpler, except that...
> a) the head intake seacock is under the vberth and access requires either lifting cushions and an access panel or pulling out a drawer and reaching a long way (if it's even reachable). I've updated the image to indicate the forward bulkhead between the head sink and head intake. As it is in the diagram, I can leave the head intake seacock closed (so long I want to flush using fresh water). I routinely close all my seacocks (except cockpit drains) when we leave the boat.
> ...


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## TSOJOURNER (Dec 16, 1999)

*sink drain/ head inlet one seacock?*

Whoa. Glad I checked out this topic.
Im getting ready to redo my seacocks and found the suggestions here that there is no reason that I cant tee into the head inlet line (below waterline) and use that for the head sink drain too (also below waterline). Hardly ever use the sink anyway. Right now I have two seacocks right next to each other. Always seemed kind of excessive. I would love to glass over one of them. Less seacocks = less maintainence and worry. 
Am I overlooking anything even if I dont intend to use the sink drain for flushing the head. Can I do it, please say yes again as I believe I heard you in this post. And where do I get a link to the Diva of head plumbing, Peggy?


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## sailingdog (Mar 19, 2006)

Yes, you can scosch...  But you'll find that the head stinks a lot less if you flush it with clean fresh water if you have to leave the boat for an extended period of time. Often, the head smell isn't caused by the waste or hoses, but by the salt water critters being in the hoses and dying and decomposing there.


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## CLucas (Feb 10, 2007)

scosch said:


> ...And where do I get a link to the Diva of head plumbing, Peggy?


Peggy Hall, "The Head Mistress" is at The Head Mistress - SailboatOwners.com. As mentioned here, she also has a popular book.


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## Valiente (Jun 16, 2006)

I did something like this in reverse for my head in my Viking 33. Keep in mind I am in Lake Ontario and therefore flush relatively clean fresh water already.

Basically, this boat is cleared out for racing and daysailing. I got rid of the evil old 10 gallon tanks in the galley and the head, and the Whale pumps were half dead anyway. People can wash their hands with "city water" brought aboard in jugs...they just have to soap up in the basin and then rinse with a "gravity bag". No different from camping, really...except the head is in full working order!

Anyway, I "stacked" the drain and the head water intake as follows:

Seacock---short length of double clamped hose---plastic T-fitting to head---short length of double clamped hose---plastic stopcock---short length of double clamped hose to sink drain SS outlet.

Method if you want to flush: Open seacock, close sink stopcock. Pump away.

Method for wash-up: Fill sink, prior or after, wash up, and either let greywater go straight out, or close seacock and pump greywater through the head.

Method for winterizing head, sink, etc. Close seacock, fill sink with pink stuff, open plastic stopcock, pump system. Slosh pink stuff in head bowl, shut 'er down.

I use the same "divert antifreeze from sink" method to winterize my engine and Lavac head on my steel boat using a simple bypass from the drain to the standpipe, which I seal from the outside to make the standpipe into a nice tall reservoir for antifreeze.


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## JohnRPollard (Mar 26, 2007)

This topic comes up occasionally, and at first it seems like such an obvious solution that everyone begins to wonder why all builders don't set-up their systems like this at the factory. But they don't typically do it this way, probably for a variety of reasons.

One issue is that sink drain seacocks/thru-hulls are usually much larger than the head/engine intake sea-cocks. So there could be a concern about constricting the flow, especially if any debris goes down the drain. If that drain/intake gets clogged by sink debris, it could take the toilet partially out of commission.

Also, drain thru-hulls usually are not as far below the waterline as intake thru-hulls. If your head intake thru-hull is a foot or two below the waterline, you could easily end-up with a lot of "standing water" in your sink drain. This may lead to as much or more stink than you are trying to cure by giving the head a fresh water rinse.

One more concerning is healing. If your head intake/sink drain is closer to the centerline of the boat, and the sink is outboard, the sink can easily end-up below the waterline, or even below the intake/drain when the boat is healed. So if you open the thru-hull to flush the toilet, you had better have a way to prevent the water from gravity draining up, into, and out of the sink.

So think it through a bit before taking the plunge. We've had good results with simply adding water to the head (we have the same shower arrangement as Christyleigh, but a cup of water from the sink works almost as well).


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## CLucas (Feb 10, 2007)

JohnRPollard said:


> This topic comes up occasionally, and at first it seems like such an obvious solution that everyone begins to wonder why all builders don't set-up their systems like this at the factory. But they don't typically do it this way, probably for a variety of reasons.
> 
> One issue is that sink drain seacocks/thru-hulls are usually much larger than the head/engine intake sea-cocks. So there could be a concern about constricting the flow, especially if any debris goes down the drain. If that drain/intake gets clogged by sink debris, it could take the toilet partially out of commission.
> 
> ...


Good thoughts to consider, John. In my situation, my head intake is closer to center line than the sink drain seacock. The head intake is also underneath the vberth -- while access is not difficult, it is not convenient (need to move a vberth cushion and raise a panel. My plan is to not even open the head seacock (unless fresh water stores are low), so the chance of any backflow is unlikely or impossible. Fair warning regarding sink debris, but the head sink is used pretty much only for hand/face washing.

Unless I'm missing something, I think the concerns you raise are more applicable to those who use the same thru-hull for sink drain and head intake.


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## JohnRPollard (Mar 26, 2007)

CLucas said:


> Good thoughts to consider, John. In my situation, my head intake is closer to center line than the sink drain seacock. The head intake is also underneath the vberth -- while access is not difficult, it is not convenient (need to move a vberth cushion and raise a panel. My plan is to not even open the head seacock (unless fresh water stores are low), so the chance of any backflow is unlikely or impossible. Fair warning regarding sink debris, but the head sink is used pretty much only for hand/face washing.
> 
> Unless I'm missing something, I think the concerns you raise are more applicable to those who use the same thru-hull for sink drain and head intake.


Okay, let me see if I've got this straight now:

Your goal is to have a freshwater flush for the head. You will get the fresh water for flushing the toilet from the head sink. You plan to "T" off the sink drain, and run a line to the toilet pump intake. You will run the faucets in the sink whenever you need water for flushing the toilet.

You will no longer be using the salt/lake-water intake for the toilet. That seacock is not easily accessible and will remain closed pretty much all the time.

Therefore, you will not be using the head intake seacock as the sink drain. Instead, you will continue to use the sink drain for its intended purpose.

Okay, now that I've walked myself through it, I see your plan better. Something in your initial post led me to think you'd be doing it a bit differently.

The remaining question is about the need for the diverter valve at the "T". Without it, you will have to close the sink drain seacock and first fill the drain line with water before it will divert at the "T". So, depending on how long that drain line is -- you might want the diverter valve. Personally, I'd install it.

You may still have issues when the boat is heeled with being able to operate the sink faucets when you need flush water. Gravity may conspire against you.

Again, this is where the set-up that Christyleigh and we have is in many respects simpler and more fail-safe. What we do is we grab the combination shower/faucet head (which is on a 6-8 foot retractable hose) and simply spray the fresh water in the toilet bowl directly. (With the added benefit that Christyleigh pointed out of a pressure wash!)


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## Valiente (Jun 16, 2006)

CLucas said:


> Unless I'm missing something, I think the concerns you raise are more applicable to those who use the same thru-hull for sink drain and head intake.


Perhaps I should emphasize that the head intake/sink drain combo thruhull seacock is normally CLOSED at all times...except when the head is being pumped or the sink is being drained directly out.

In fact, all thru-hulls except the seawater engine intake and the two cockpit drains are closed at all times...except when a sink needs draining.

My goal in life is to reduce open holes in boats and to reroute all vent lines to the top of the cabin, insofar as this is practical. The common way of doing things makes me nuts.


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