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Kathleen C. Matlock
Username: kcmatlock

Post Number: 8
Registered: 01-2008
Posted on Friday, August 19, 2011 - 11:55 am:   Edit Post Print Post

I forgot to add that, like Gritz, I'm a big vinegar user in my head. A little splash goes a long way toward eliminating crusties and nasties on a regular basis.

Eric Gritzmacher
Intermediate Member
Username: eneveaux

Post Number: 12
Registered: 08-2008
Posted on Friday, August 19, 2011 - 11:10 am:   Edit Post Print Post

Like KC, i keep my seawater intake closed, especially when in a harbor or marina where the water is usually nasty. Also, when pumping into the holding tank, i try and use fresh water whenever possible. I just use the faucet from the head sink - it has an extension. About the only time i use seawater is when i need to conserve fresh water. Even then, i will flush through some fresh water after using seawater. A little diluted vinegar from time to time also helps.

David Sheriff
Board Administrator
Username: admin

Post Number: 343
Registered: 01-2004
Posted on Tuesday, August 16, 2011 - 10:52 am:   Edit Post Print Post

What a terrific, simple idea Kathleen. Actually, I do the same thing when I have some surplus fresh water, like a thermos of hot water that has finally cooled. I find, however, that it takes a few days for the seawater intake in my head to go anerobic. Once I purge it with the first flush, it's pretty good after that.

I'm slightly overboard on working out ways to minimize fresh water use on my 28' Islander. The tank holds 24 gallons and I like to see sometimes how long I can make it last.

I also have a powered vent fan in the head. I've accepted that there will be some head odor and do what I can to get rid of it. The fan was originally a solar powered Nicro, but the motor lasted just a few months longer than the 3 year warranty. On inspection, the commutator and brushes were metal as the fan ran on 2 volts. Wear is inevetable, so figure on replacing every three years. I put a 12 volt computer fan in mine, but your mileage may vary. The way you have to put in the fan, it is very sensitive to saltwater, so it's easy to kill if you don't shut the vent religiously every time out.

The latest on the fan: I put in a on-off switch in the head so I don't have to listen to the fan whine when i close the vent. Also, I ran a 4 inch aluminum flexible duct to the vent opening and moved the fan down to waist-level in the corner. If you suck stale air out there you don't draw fragrance past your nose standing in the head.

Kathleen C. Matlock
Username: kcmatlock

Post Number: 7
Registered: 01-2008
Posted on Monday, August 15, 2011 - 09:46 pm:   Edit Post Print Post

I can vouch for the fact that the entire system smells a million times better with the elimination of a salt water flush. I have my salt water intake thru-hull closed and don't use it. However, in my case, it was an easy option to use fresh water. My head has a foot pump that is fresh water plumbed. I just use that to put fresh water in a cup, then dump it in the bowl to flush using fresh water. Easy solution, no modification.

David Sheriff
Board Administrator
Username: admin

Post Number: 342
Registered: 01-2004
Posted on Friday, August 12, 2011 - 03:43 pm:   Edit Post Print Post


Something for your board. I forgot how to post.

Once before a trip I installed a new hose between the thru-hull valve and toilet which eliminated the bad smell. A bit challenging to change a hose out before every trip, so I'm toying with the idea of installing a "T" in hose at the toilet end, running a hose form the "T" up to above waterline and installing a valve with garden hose connection. Before a trip, could attach garden hose and back-flush the nasties into the ocean. Anybody else tried this?


Anything that flushes out the stagnant water should help. I put in a head once that drew from two through-hull fittings with a tee at the head. The water in the hose circulated enough to stay oxygenated.

David Sheriff
Board Administrator
Username: admin

Post Number: 341
Registered: 01-2004
Posted on Thursday, August 11, 2011 - 04:52 pm:   Edit Post Print Post

Using seawater to flush the head on a boat has one large drawback. Returning to the boat after an absence, the first flush will probably smell awful. As I also have seawater plumbed to my galley sink, I have the problem in spades.

The traditional explanation is that animal and vegetable organisms in the water die when they sit in a hose for a while. Their decay produces the stink. This is the explanation provided in the best book on marine sanitation: Get Rid of Boat Odors by Peggy Hall.

I have never been happy with the "death and decay" explanation. Now I think the answer is simply aerobic vs. anaerobic conditions in the stagnant hose. Anaerobic bacteria produce many substances that smell bad to us.

Seawater contains both types of micro-organisms but the aerobic ones flourish in surface waters. Once the biochemical oxygen demand in stagnant water uses up the dissolved oxygen, the anaerobes quickly spring into action. They continue to feed on organic matter, fermenting it. Products of different fermentation reactions include lactic acid (sour milk smell), propanoic acid (sweat, swiss cheese), butyric acid, well - enough right there.

Humans can detect butyric acid in very low concentrations. It's a predominant smell in b.o., feces, rancid butter and more.

Anaerobic bacteria also make holding tanks smell bad. Add enough oxygen to keep the tank aerobic and it should smell better, according to Ms Hall. I have been injecting air into my boat's holding tank via an aquarium pump for several years. This is basically the Groco Sweet Tank system. Yes, it works. There are enough qualifiers to that statement, however, that it deserves a report of it's own.

I have seen a number of boats eliminate the seawater intake smell by plumbing fresh water to their toilet fixtures. This does take care of the odor. Do not do this unless the fixture is designed specifically for pressurized water. Connecting fresh water to your old head fixture will cross connect the two systems to the possible detriment of your health.

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