Fresh water toilet - thoughts?

[Gard]

We all know that salt water and urine makes the head stink. We all have many stink prevention tricks and remedies up our sleeve that we would like to share. Please keep those to yourself and focus on the question - flushing with fresh water.

Flushing with fresh water would take care of any stink and estetics problems, and be friendly to pipes, pumps, etc.

You would of course need an abundance of fresh water. You would either have
to have a watermaker, or you would need to carry the equivalent to the ammount of septic you will produce on a given trip (if you dump to sea and not to land - who knows how much that could be?).

Presupposing a water naker: Fresh water flushing, with the option to switch to sea water - does it sound enticing?

I think my only concern would be bacteria contamination of the watersupply that I use for everything else. I would really like to get your thoughts on this.

I think the only sure way to keep bacteria away would be to have a separate water tank or cistern dedicated to flushing - and keep this tank filled from the top by a pump from the main tank. The downside is of course the extra space and weight. I'm not sure I would trust membranes or baffles to prevent backflow and spread of bacteria through piping and back to the main tank.

[Chotu]

Lots of boats use fresh water for flushing. I have ones two of them.

It’s not necessary to have separate water tanks or cisterns. All of the freshwater flush systems I have seen use a check valve. That keeps water flowing in one direction, into the bowl.

In addition, and in reality, it’s not really that common anyway for the water to come from the bowl and go backwards upward and against gravity through the holes at the top of the bowl into your freshwater system.

There’s definitely no problem using a check valve for this.

This is what every RV in the world does. And all of the boats I have ever seen.

So just plumb it straight in. You don’t have to alter anything about your water tankage or plumbing at all. Just the check valve.

The only time it might get slightly more complicated is when you have a manual pump on the head. I guess there are some potentials of that pump failing and mixing up the two things. Technically the check valve should work in that situation also. But more peace of mind if you Use an electric head.

[Gard]

Originally Posted by Chotu

Lots of boats use fresh water for flushing. I have ones two of them.

It’s not necessary to have separate water tanks or cisterns. All of the freshwater flush systems I have seen use a check valve. That keeps water flowing in one direction, into the bowl.

In addition, and in reality, it’s not really that common anyway for the water to come from the bowl and go backwards upward and against gravity through the holes at the top of the bowl into your freshwater system.

There’s definitely no problem using a check valve for this.

This is what every RV in the world does. And all of the boats I have ever seen.

So just plumb it straight in. You don’t have to alter anything about your water tankage or plumbing at all. Just the check valve.

The only time it might get slightly more complicated is when you have a manual pump on the head. I guess there are some potentials of that pump failing and mixing up the two things. Technically the check valve should work in that situation also. But more peace of mind if you Use an electric head.

Do you install a "Y" valve to be able to seitch to seawater - "just in case"?

Also, what are your thoughts on being able to flush with fresh water? Great, good, sucks?

[Chotu]

Originally Posted by Gard

Do you install a "Y" valve to be able to seitch to seawater - "just in case"?

Also, what are your thoughts on being able to flush with fresh water? Great, good, sucks?

No Y valve. The 2 fresh water flush boats I’ve had (and all RVs) just come straight off the pressurized fresh water system. They just view it as another use of fresh water. I think they are right in that philosophy. It doesn’t take much extra water, surprisingly. Like doing another sink full of dishes each day.

The “just in case” is have adequately sized tanks, be more careful of water consumption all over the boat, or have a watermaker.

Flushing with fresh absolutely keeps the head from stinking.

I know that theoretically it’s supposed to cut down on the crystals in the sewage hoses, but, I still found plenty of crystals in the boats that I had that were freshwater flush. Ha ha. Overall it’s a lot more pleasant though.

And it does eliminate some other annoyances that have to do with saltwater flushing. The thru hull. I don’t know how many times my through hulls have had a big oyster or whatever plug them up. And all sorts of growth in them. That same growth can make it through to your pump and cause issues.

All in all, I’d say the fresh water flush is more reliable

Definitely preferable if you can handle the water usage. Which really isn’t all that much, but it is Additional.

[Jolly Roger]

Chotu answers the questions perfectly, and I concur.
I converted both my electric Raritan Elegance heads to fresh water when I dumped the manual contraptions years ago. Raritan has a conversion kit, but it’s pricey, and only has one check-valve.
I had worries about back flushing, so I incorporated a one-way valve, a manual ball valve, and a water solenoid/cut-off, the seacock is also closed when on freshwater flush. I can change to seawater flush in about ten minutes.
Of course, I helps to carry 325 gallons of water, and we recently did a four-day passage with five adults on board, without even bothering to change over.
The effort to incorporate freshwater flush completely eliminates the stink.
Take a look at the article I wrote on this subject on my website.
Installing two electric toilets

[sailorboy1]

Originally Posted by Gard

You would of course need an abundance of fresh water. You would either have
to have a watermaker, or you would need to carry the equivalent to the ammount of septic you will produce on a given trip (if you dump to sea and not to land - who knows how much that could be?). I wouldn't call the water needed an "abundance". There are 2 of us on our boat and I can not really tell the difference in water use now with fresh water flush than from before

Presupposing a water naker: Fresh water flushing, with the option to switch to sea water - does it sound enticing? no, I switched to fresh water flush for a reason.

I think my only concern would be bacteria contamination of the watersupply that I use for everything else. I would really like to get your thoughts on this. not an issue. the flush water is under pressure and comes in at the top. The waste in the bowl isn't ever going to get in the system

I think the only sure way to keep bacteria away would be to have a separate water tank or cistern dedicated to flushing - and keep this tank filled from the top by a pump from the main tank. The downside is of course the extra space and weight. I'm not sure I would trust membranes or baffles to prevent backflow and spread of bacteria through piping and back to the main tank.over thinking wasted worry

Odor from fresh water flushing has been much less. There has been a lot less scaling, but there is still scaling unless you are willing to flush a lot of water each time.

No reason to reinvert the fresh water flush wheel.

[Shrew]

I wouldn't re-invent the wheel or over-engineer this. Raritan makes either the Sea Era or Marine Elegance models of freshwater and dual (selectable fresh or raw water) flush. There is no need to allocate a new tank. The system protects your potable water.

We installed a Sea Era because we didn't have room for a Marine Elegance. They both work exactly the same way. We love ours. We got the dual flush model, but never bothered installing the raw water pump and simply capped off the seacock instead.

[Little Song]

Use saltwater to flush. After the job is done flush some freshwater from the shower/tap. Once in .every two weeks add some drips of vegetable oil to lubricate the toilet system rubbers.

[Shrew]

Originally Posted by Little Song

Use saltwater to flush. After the job is done flush some freshwater from the shower/tap.

We used to do this with a manual flush head we had on a previous boat. Though we were only weekending then, so we would pump back enough freshwater to flush the entire discharge hose. We'd flush with a little freshwater at night before we went to bed to reduce odors.

You'd have to flush a lot of freshwater to displace the volume saltwater in the discharge hose. Which is what would be needed to reduce the calcium build-up in the line. I guess it depends on what you're trying to prevent..odor, or scale build-up.

[steve1122]

In the plumbing trade, this is called a backflow preventer. There are various ways of doing it- here are a couple:

with an air gap:

https://www.watts.com/products/plumb...s-watts/919agc

or a double check valve assembly:

https://www.supplyhouse.com/Watts-00...xoCDOgQAvD_BwE

hope this helps

-Steve

[flightlead404]

Originally Posted by Gard

Do you install a "Y" valve to be able to seitch to seawater - "just in case"?

Also, what are your thoughts on being able to flush with fresh water? Great, good, sucks?

I'm considering doing this for the opposite reason.

We use fresh in the summer day sailing etc because its plumbed that way and an electric head.

We use buckets and salt/brackish/river water in winter when we're cruising because we don't have a water maker.

We don't have any smell.

[Dockhead]

I think it's a great idea to fresh water flush. I'm not concerned about the smell -- my toilets don't smell except when first flushed after seawater has been standing for a long time in the supply lines, and that's a trivial issue. What I'm concerning about is precipitated deposits in the waste lines.


This can be prevented by flushing through with a LOT of seawater, but if you are on a holding tank for a long time, you have a problem.



I will probably replace my aft toilet this winter with a convertible fresh-sea flushing one.

[accomplice]

We have freshwater flush heads (3 x Jabsco 37275). Each head has a pump that draws from one of the water tanks. There is also the option of closing the line from the tanks and drawing instead from seawater. There is a checkvalve on the line from the water tank.

On occasion when the watermaker was not working we switched to seawater flush. Not only was the smell much worse, but the hoses quickly built up scale. It is my understanding that the hose diameter for the fresh water flush is smaller than for the seawater flush, and thus it blocks sooner.

I have found that the water used by the freshwater heads is a small fraction of the water used onboard.