Raw to fresh

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Rick L

We use fresh water from a bucket to flush the head in our Hunter 430 - seems to keep holding tank smell down. Head is plumbed to draw from seawater. Have considered plumbing the intake into our fresh water system but not sure if this is safe or would work. When fresh water pump is on, would this put too much pressure on head valves? Will it work with fresh water not pressurized? Is it safe in terms of backflow into fresh water system? Thanks Rick
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
add a small aux. tank.

Rick: Have you considered adding a small aux. tank (5-6 gal) You can have this tank fed from the primary tank with the current pump. Add a shut off valve and/or a one way valve to the system. This way you can have the best of both worlds.
 
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Peggie Hall/Head Mistress

Don't even consider it

ONLY toilets designed to use pressurized water can be connected to the fresh water system without risk of polluting the potable water supply and damage to the toilet. Your only choices are a separate tank used only for toilet flushing, or a new toilet designed to use pressurized water. If the toilet on your boat is electric with integral intake pump (iow, the intake pump, and discharge pump and macerator are all part of the same unit, powered by the same motor), flushing for any length of time with the intake seacock closed has destroyed the intake pump impeller and has most likely irrevocably damaged the intake pump housing. Since you're on a holding tank, instead of installing a separate flush water tank, I suggest you replace the toilet with one designed to use pressurized flush water. They use half the flush water, less than half the current draw and are almost silent (it's the intake pump that makes all the noise and needs most of the power). You should be able to salvage your existing bowl, which means you can go with a conversion kit--the Raritan SeaEra would be my choice...check it out on the Raritan website (link below). When you consider that ou'd need at leat a 20-25 gallons flush water tank to make it worth the effort, plus hoses, a vent thru-hull and a separate deck fill, the cost difference would only be about $100, if that much. Or, for a boat the size of yours, why not go with a Lectra/San that would let you flush waste overboard using seawater? If both the heads on your boat are connected to the same holding tank, one of 'em is at least twice as far from the tank as should be anyway, 'cuz much more than 6' from the head to a tank is guaranteed to leave waste sitting in the hose to permeate it. Check that out on the Raritan website while you're there too.
 
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Peggie Hall/Head Mistress

Sorry, Steve...

Any "interface" between a toilet and the fresh water tank/plumbing without the necessary backflow preventers and siphon breaks in the toilet itself creates the potential to pollute the potable water. Unless connected to a toilet designed to use pressurized water, any flush water supply must be totally separate from the potable water system. Plus, a 5-6 gallon tank would barely last a day. Raw water electric toilets draw at least half a gallon a flush...the average person uses the head 5 times a day. For just two people, that's at least 5 gallons of flush water a day. Add a coouple of kids or guests, and the smallest tank worth the effort to install it is 25 gallons.
 
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Mickey McHugh

Consider this

Our dealer said we should use fresh water when ever possible for the head to keep down the bad smells and keep salt out of the system. So one of the first things we did on our 40.5 was put a tee between the head sink drain and its thru-hull valve and another tee between the head intake thru-hull valve and the head pump. Then we connected the two tees using a valve (cross-connect). Every connection was doubled clamped. To use fresh water, just close both thru-hull valves, open the cross-connect valve, fill the sink with just enough fresh water and flush. To use RAW water, just close the cross-connect valve, open the head intake thru-hull valve and flush. To drain the sink, open the sink thru-hull valve. We NEVER use a sink drain stopper for the head sinks. If you pump the head with a stopper in the sink, it really gets hard to remove. It sounds simple and believe me, we have lived aboard for 5 years and it has been painless (and odorless) to use. When guests come aboard we just tell them to put water in the sink and pump away. No valves to worry about. We spent under $50 and 2 hours to convert 2 heads to fresh water flushing.
 
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Tony

shower head

On my 340, the shower head reaches to the head since it it right above it. i keep thru hull closed and just hold shower head over bowl, run fresh water in and pump away. never have intake line smell. i realize this uses fesh water probably faster than i should and might increase my pumpout frequency ( peequency?)but i am willing to do this in order to have the odor free head . so nice to come back to boat after a week and not have that first flush awfulness. Befor i leave boat for any period of days i fill bowl with fresh water from shower, ad a little KO (great product) and flush to a few inches left, Thus any small joker valve leakage is essentially fresh also. When in port i have a fresh water connection to boat from town ( with pressure reducer and only connected when i am in the boat, Peg !!) It makes the john almost like home. tony
 
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Peggie Hall/Head Mistress

Close intake seacocks ONLY if toilet is manual

Closing the intake for most electric raw water flush toilets will damage the toilet. Mickey, unless your system is designed to close the sink drain line when using raw water (which, since it puts suction on a plug, it doesn't appear to be), I don't know how your toilet is able to prime without a plug in the sink...'cuz the toilet will pull air into the line through the sink. And if you sail with the head intake thru-hull open, in the right conditions the "ram water effect" can turn the sink into a fountain. Since opening the thru-hull drains the sink drain line, it should also relieve the suction holding the plug in the sink. If not, try a slightly larger plug...it sounds like the one you have may be just enough smaller than it should be to let it drop too far into the hole.
 
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Mickey McHugh

Cross-connect Valve

Yes, my heads are manual (I would hope Tony’s is too) so it’s OK to close the intake thru-hull valve. Please note that in my system there is a valve in the line between the tees, (I called it a cross-connect valve). It is always closed if I use RAW water to flush, which as been 2 times in 5 years when we were crossing the Gulf of Mexico and wanted to conserve fresh water. As Peggie points out, it would NOT be safe nor work properly without that valve. GOD, to think I did something right the first time. Right after we installed the system and it was configured to use sink water, the sink drain plug (which fits the drain perfectly) was put in by mistake and the head was pumped (only a quarter of a stroke since the line was plugged and the resulting vacuum sucked the plug in tight). I opened the sink drain thru-hull valve to relieve the suction BUT it was still hard to pull the plug. I just wanted to share one of my mistakes with everyone. (I have lots to share but little time for it!)
 
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Stan Rogacevicz

Fresh Water Flush

Peggy, If you re-read Micky's post you will see that none of the problems you mention will happen if it is properly used. I set up my c28 for 3 years and my c320 for 3 years the same way. The plumbing ends up looking like an H schematically with the valve in the horizontal line of the H. Both thru hulls are allways closed and the valve is open to flush Fresh water from the sink. As long as there is sufficient water in the sink I don't see how an electric would know or care where its water was comming from. Simply close the valve and open the 2 thru hulls (bottom legs of H)and the modification dissapears. I'm sure Micky's comment on sucking down the plug was in the Fresh water flush mode was just a comment not describing a 'problem' because of course when you are sucking water down the sink drain you don't want to plug it. The 'ram water effect'you mention would only be possible if you Forgot to close the valve between the 2 systems when choosing to flush with Raw water by opening the Raw water intake. That same Mistake would also cause the sucking of air down the sink you mentioned when Incorrrectly set up for a Raw water flush. Stan "Christy Leigh" c320 #656
 
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Peggie Hall/Head Mistress

If the thru-hull is closed

And there's no water in the sink either, dry friction heat will "fry" the intake impeller in the toilet if the toilet is run. Even if it's only run dry briefly, dry friction heat wears away the edges of the impeller vanes...it only takes doing that a few times to wear 'em enough to destroy the impeller. "I'm sure Micky's comment on sucking down the plug was in the Fresh water flush mode..." I think you'd better re-read my question, Stan...I was referring to the raw water mode. If there were a plug in the sink in the "fresh water mode," how could the toilet draw any water out of the sink? However, Mickey answered my question: he installed a valve in the system that prevents the problems that can occur in raw water mode.
 
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Peggie Hall/Head Mistress

Mickey, how 'bout sending me a drawing

Of your design? I'm still working on revisions and illustrations in my book...the "intake odor cure" described in it (same one that was in the HM library) was the brainchild of a boat owner...your systems sounds like an improvement on it that I might be able to use (properly credited, of course). My e-mail address is in the directory.
 
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Stan Rogacevicz

Used Properly

..and if you don't open up the thru-hull for your engine you can also fry an impellor. I posted to make sure that it was understood by all that the system Micky and I have been using for years is an excellent addition and if used properly there are no drawbacks. Of course if you don't put water in the sink you will cause a problem trying to flush with Fresh water. So knowing your expertise on the subject my question is - Is there enough space in the average sink and couple feet of line to support 1 flush for an electric head? If so why not use it? If not then my comment in my original post was incorrect. Everything I hear about electrics claims Less water use that's why I made the comment that it didn't matter manual or electric. Stan "Christy Leigh" c320 #656
 
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Mickey McHugh

One and a half gallons

Stan - I measured and my sink holds about one and a half gallons so if you fill it, you should be able to do at least one electric flush. We ALMOST bought one at this year's boat show but opted for a genset. We liked the idea of not having to pump by hand so our boat is more like a house. Just remember to keep the pump quiet by using Super-Lube. Peggie - Will do. I'll contact you by email.
 
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Peggie Hall/Head Mistress

Flush water use depends on the toilet, Stan

Raw water electric toilets on which the intake pump is integral to the discharge need the most flush water of all marine toilets--manual AND electric--because you can't control the amount of flush water. The intake impeller is powered by the same motor as the discharge, and so the toilet must pull in water as long as it's being flushed to prevent frying the intake impeller. Some electric toilets that have separate remote intake pumps use less flush water, because the intake pump has its own motor...high-end toilets can even be wired to include a "dry" flush mode. Toilets that are designed to use pressurized water use the least flush water of any electric toilet because there is no intake pump, just a solenoid valve that starts and stops the flow water, just like opening and closing a faucet. As for whether a sink holds enough water to flush any toilet...no "one size fits all" answer to that one. How big is the sink? How far is the tank from the toilet...iow, how long do you have to keep flushing to move the bowl contents all the way to the tank? If the tank is close, the 1.5 gallons Mickey mentioned may be way more than you need, causing you fill up your tank much faster...if it's more than about 6' away, it may not be enough, giving you a choice of continuing to flush after the water in the sink is gone and frying the impeller or leaving waste sitting in the head discharge hose to permeate it. My advice to people who want to flush with fresh water is: buy a toilet designed to use pressurized water. However, if the boat is too small for that to make any sense, there's still an easy way to eliminate seawater intake odor that works on most boats, and is similar--but not nearly as complex--to what you and Mickey have done: tee the head sink drain line into the head intake line. Once a day--and especially when closing up the boat--close the intake seacock, fill the sink with water, flush the toilet...rinsing all the seawater out of the whole system. Adding a healthy squirt of Raritan C.P. makes it work even better.
 
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Rick Lober

Thanks All

Thanks all for the ideas and discussion. Will probably give Mickeys idea a try - although using the shower head is also pretty simple with no mods.
 
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