Dumb toilet ("head") question

[Blackduck]

Showing my rank amateur status etc.etc. I was wondering why you can't "adapt" a house cistern to your head. Mine is a catamaran so while it moves and yaws and rolls a bit, it's not a big heeler. So why wouldn't a small house cistern fitted above the intake pump (in my case in one of the over-sink cupboards) and adjusted down in capacity by lowering the float work?. Feed the pressurised water into the inlet (just like a house fitting) so that the "float" turns it on when needed and off when full (as I say I would imagine setting the float low so full is not really overflow style full). Silicone the standard outlet (the one that lifts when you press the flush button on the cistern so it is closed) and pipe the "overflow" to the sink waste pipe. Then drill a new outlet into the bottom of the cistern and attach that to the inlet of the pump for the toilet. You press the flush button (electric toilet) the pump draws water from the cistern. The pump stops, the float opens the inlet and refills the cistern.
I know I must be missing something? Is it just the rock of the boat making it hard to set the float? Or is it something else. If this idea is too ridiculous for words then I stand in the dunces corner.

[catsketcher]

No ideas is ever ridiculous and some ridiculous ideas find their way back in favour - foils took 50 years to be viable in multihulls (Search Dave Kieper and Wiiliwaw if you want a trip down multi history)

Most boat toilets are below the waterline and need pumping UP to get the waste out of the toilet. As normal toilets are gravity fed they can't work in this way. On my cat the top of the toilet is 100m above the waterline (it helps not sink the boat) but I still couldn't use a normal dunny.

If you decided to put the toilet on the bridgedeck then go ahead. It will work especially well if you plumb it straight down. I have heard of Hitchiker 40 with this arrangement. You could even plumb it into a holding tank that was also above the waterline so you could discharge easily when sailing. (That is what we do when cruising - holding tank on when anchored, discharge at sea when 5-10 miles away from anywhere doing 6 knots or more with a gravity discharge tank).

So if you have a space in the bridgedeck then go for it but there are few cats with bathroom soles high enough for it to work.

cheers

Phil

[StuM]

May be OK if it's fresh water flush and you've got enough fresh water storage. Personally, I'll stick with sea water flushing. And I wouldn't want sea water sitting in a cistern for too long. It can get a bit funky once the microscopic organisms start to die off

The other thing to worry about is back-contamination if your head/cistern are plumbed into your fresh water supply in any way and things get stirred up by boat motion.

[StuM]

Originally Posted by catsketcher

On my cat the top of the toilet is 100m above the waterline (it helps not sink the boat) but I still couldn't use a normal dunny.

Do you have to climb the mast to take a dump?

[44'cruisingcat]

That's a long drop!

[44'cruisingcat]

Originally Posted by Blackduck

Showing my rank amateur status etc.etc. I was wondering why you can't "adapt" a house cistern to your head. Mine is a catamaran so while it moves and yaws and rolls a bit, it's not a big heeler. So why wouldn't a small house cistern fitted above the intake pump (in my case in one of the over-sink cupboards) and adjusted down in capacity by lowering the float work?. Feed the pressurised water into the inlet (just like a house fitting) so that the "float" turns it on when needed and off when full (as I say I would imagine setting the float low so full is not really overflow style full). Silicone the standard outlet (the one that lifts when you press the flush button on the cistern so it is closed) and pipe the "overflow" to the sink waste pipe. Then drill a new outlet into the bottom of the cistern and attach that to the inlet of the pump for the toilet. You press the flush button (electric toilet) the pump draws water from the cistern. The pump stops, the float opens the inlet and refills the cistern.
I know I must be missing something? Is it just the rock of the boat making it hard to set the float? Or is it something else. If this idea is too ridiculous for words then I stand in the dunces corner.

Should work, but you'd need to make sure the cistern lid was watertight, so that sloshing around doesn't leak.

I'd also suggest a non return valve between the toilet and cistern, you can't have too much backflow prevention in this area.

[Blackduck]

Thank you for your thoughts. I will continue to investigate. What I am intending this "house cistern" to serve as is simply an automatic fresh water reservoir with an air gap (and yes I would add non return valves) to change the toilets from salt to fresh water. So it wouldn't work the way it does in a home using gravity, the pump for the head would still do all the work.

[seahag]

Interesting idea. For our boat, it would be a great thing but not for the toilet. We could use a fresh water gravity fed tank to supply the sinks, or even to fill small jugs or have a spigot into our filter tank.

[StuM]

Why do you want fresh water flush? How much water do you store and how do you replenish it?

[Blackduck]

I am looking to go fresh to avoid the odour associated with salt water flushing

[44'cruisingcat]

Another thought. You'd need to mount the cistern so it's about the same height as the toilet, otherwise water from it will just run down into the toilet, probably overflowing it. Or install a shutoff valve between toilet and cistern, which you'd only open when flushing.

[Kenomac]

Originally Posted by Blackduck

I am looking to go fresh to avoid the odour associated with salt water flushing

If your boat is here in the Adriatic, you won't detect any odor from the salt water.

In Southern California the ocean water stunk, mainly due to harbor pollution in LA harbor and the red tide plankton blooms, so changing over to fresh water was always on our list to do. But over here in the Med, we've never experienced the issue. You'd never even guess the water is salt water being flushed through the heads... clear and odorless.

Save you money for another project.

[Blackduck]

In fact it was purely an idea based on hearsay: of salt water odour. ( add to that and the fact I have been in a river for winter I haven't yet smelled it. But wanted the best I could in advance. So good advice I shall hold off.

[Kenomac]

Where are you located? I'm also up an estuary here in Italy.

[DMCantor]

The only time there is odor with salt-water flushing is if the head hasn't been used for several days. The plankton in the seawater dies for lack of oxygen, and releases all kinds of smelly gasses. If you are using your head every day (ie cruising), no reason at all for any odor.