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rmeador 06-23-2010 11:04 PM

converting raw water head to fresh water
The boat I'm thinking about buying currently has a manual raw water flush head. I've been told that using raw water can lead to smells. Since I'm going to be living aboard, at a marina most of the time, I think I can spare the fresh water to use for flushing. How hard/expensive is it to convert a head? Do you think it would be worth it? Sadly I do not know the brand of head currently installed in the boat. Would it be better to replace it entirely? Does a fresh water flushing head work more like the ones you find in a camper (i.e. no pumping, just step on a lever or push a button)? Thanks.

mitiempo 06-24-2010 12:07 AM

You can use the same head. Just change the intake from the through hull to a fresh water tank or use a T and insert fresh water that way. In my experience a head used often should not smell, but one where the water sits for a long time will. I am also a liveaboard.

Omatako 06-24-2010 02:27 AM

Salt water that is trapped in the lines for a few days will give you a hydrogen disulphide smell but it will come and go in seconds - it does not linger. And as has been already posted, if you're living aboard and using the head regularly it won't smell at all.

The smell you're worried about is IMHO definitely not worth replumbing the head to fresh water. Eventually you're going to want to sail overnight or longer then you won't have the marina fawcet to rely on.

christyleigh 06-24-2010 06:28 AM

There are a couple options that don't leave you stuck with fresh water only if you are away from your marina.

On my last 2 Catalinas the head and head sink drains were close by so I plumbed in a valved connection from the head sink drain to the head pump intake to grab fresh water from the sink drain. Picture an H with the left side being the head sink drain, the right side being the head input, and the horizontal being my connection with a valve/switch in the middle. Depending on your existing plumbing it can be simple and switchable using the 'wet bowl' setting on your head and proper settings of the thru-hulls.

Another option that can be used with most boats that have the shower head within reach of the head is to simply use the shower faucet to flush with..... which actually cleans the bowl much better than the normal head flow. My current boat has a separate shower but at the sink it has a second shower faucet which I use to flush with using the 'dry bowl' setting on the head.

svHyLyte 06-24-2010 07:21 AM

Should you choose to add fresh water, it would be wise to install a -Y-Valve allowing you to use sea water when appropriate; and, a dedicated fresh water tank for the head (perhaps a bladder tank). Do not connect the head to the same fresh water system that might be used for food preparation or consumption. The consequences are obvious.

sailingdog 06-24-2010 08:22 AM

First, as svHyLyte has pointed out, you should NEVER connect a head to the potable water system without a really good and positive vacuum break and disconnect between the two. The most common way to set up the head to pump freshwater is to plumb the head intake line in to the head sink drain line. This is really simple if the head sink drains via a through hull that is below the waterline. To flush with sea water, just plug the sink and it will draw water up through the seacock. To flush with freshwater, close the seacock and fill the sink.

I'd point out that if you're actively using the boat and head, flushing with seawater is fine, since the water doesn't stay in the lines long enough for the plankton and such to die off. However, if you're going to be away from the boat for a while, flushing the head intake line and such with fresh water makes sense. This allows you to conserve the fresh water for when you need to use it. BTW, don't use the shower to flush the head, since that will leave the intake side still full of salt water and lead to that side stinking... :D

CLucas 06-24-2010 08:25 AM

On the advice of others here on Sailnet (thanks, SD), I tapped the head sink drain into the head intake line so that the fresh water from the sink drain (i.e. after washing your hands) is used to flush the head. A diverter valve, a T-fitting and a bit of hose did the trick. It's a very simple solution to a stinky problem. Here's a diagram:

EDIT: Just re-read your post and noticed you're going to be living aboard, so this solution may or may not be workable for you.

christyleigh 06-24-2010 10:54 AM


Originally Posted by sailingdog (Post 616392)
BTW, don't use the shower to flush the head, since that will leave the intake side still full of salt water and lead to that side stinking... :D

It won't stink if you never flush with it. My head smells fine. Since we only visit the boat on weekends salt water flushing is not an option because of the smell. The salt water has been sitting in my intake for 5 years and it will stay there. The 100 gallons of fresh water I carry does fine for our week long vacations on a mooring.

The O.P. was a live aboard so there is no reason not to use the shower. If he goes on a trip one or two flushes will clean out the dead sea water and then he can use the salt water daily if needed.

RichH 06-24-2010 11:46 AM

You should consider to follow standard 'sanitary' piping rules and regs. so that the fresh water system isnt 'retrograde contaminated' from the toilet/head !!!!

... and this isnt easy to do on a boat. Check valves, y valves, etc. CAN NOT do the job of protecting a fresh water system from retrograde contamination.
To do this job properly you have to 'cobble' a system that functions similarly to a household toilet .... the water system delivers to ***separate Tank*** and the separate tank delivers to the toilet ****through an 'air gap'****. The separate tank has a valve on the INLET of the fresh water to the separate tank and that valve ***IS ABOVE THE LEVEL OF THE WATER in the separate tank***. Thats the NSF and 'sanitary' regs.' for all 'toilets' in the USA where the 'supply water' is connected to POTABLE water. This PREVENTS harmful bacteria from entering 'retrograde' into the potable water supply ... bacteria moving against the normal flow of water.

jjablonowski 06-24-2010 04:32 PM

The sink drain and the head raw-water intake on my Catalina 25 share the same through-hull with a T connection.

When I want to flush fresh water into the head, I fill the sink, close the through-hull ball valve, then suck the sink dry with the head.

(Works great for pulling pink antifreeze into the head, too.)

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