Winning the Battle Against Holding Tank Odors

Posted by Darrell Nicholson at 12:51PM - Comments: (11)


Drew Frye "sniffs" his test tanks with a gas sensor.

Take a look at this photo and imagine it is your backyard. Or your patio, or balcony. Yep, those are sealed 5-gallon buckets full of iguana poop and “other” waste, ripening in the Chesapeake Bay area's autumn sun.

Do you ever wonder whether those bright blue bottles of chemicals that claim to eliminate your head odors actually work? So did we. Did you ever wonder how the neighbors would react if you set up a head odor testing facility in your backyard? So did PS contributor Drew Frye. So far, it seems, “Operation Potty Odor,” has not alarmed the local zoning tipsters, but it is yielding some interesting results.

“They [the neighbors] have learned not to ask questions about what goes on over here,” says Drew’s wife, Laura, only half-joking.

The February issue of Practical Sailor, due out next week, features the results of our first two articles in a series on controlling head odors. For the main article, a test of odor-control chemicals, Frye collected, “flushed,” stored, and sniffed (both with his nose and a four-gas sensor) iguana poop and other waste, then added various products designed to control odor. Yes, I did say iguana poop. It came—if you must ask—courtesy of the Frye family pet, Ziggy.

Readers may remember Frye as the tester who nearly reduced the family washing machine to a bucket of bolts in his quest for a safe and effective method for washing ropes. He’s just that kind of guy.

The results of Frye’s olfactory adventures so far are mixed. As Frye is quick to point out, chemical additives are just part of the equation, and likely a small one. The real trick to achieving a sweet-smelling boat is in designing a system that promotes the biological processes that help eliminate odor. Cut off air-flow, and you’re sealing in the stink. Add chemicals, like chlorine or formaldehyde—still found in some products despite its recent classification as a known carcinogen—and you may stop the process altogether.

Apart from Frye’s finding that a holding tank is an excellent reservoir for highly explosive gases, one of his more exciting discoveries was that any product's claims of “odor-eating bacteria" should not be taken at face value. Frye’s attempts to nurture a bacterial culture from the four products that made this claim failed in all but one case. And wouldn’t you know it? The most effective product that used active bacteria — as opposed to enzymes, bleaches, and perfumes — is no longer on the market. When we called Dustin Stroth to tell him his VanishOdor product was holding its own in Frye’s test, he sighed, as if he’d expected as much. The Sarasota, Fla. entrepreneur who developed the product had recently decided to throw in the towel after several years of lukewarm sales.

Our test field faces off before the event. VanishOdor is the green-labeled bottle on the right.

“I’m not surprised,” he said. “It’s a good product, but it never really caught on.” Stroth shut down the supply line last fall. “I had bills to pay, and it was time to move on to something else.”

Stroth says he still has a few bottles on hand, and his website is still up for orders. Anyone who wants to give the product a whirl can order some of the remaining stock from his website, Because this is a product that boosts the biological processes, it will not work as well in poorly-ventilated holding tanks. Warmer temperatures are preferred. Our test identifies four other products that will effectively combat holding tank odors, one for less than $10 per season.

Frank Lanier's stealthy holding tank test setup demonstrates his cunning.

In a companion article to Frye’s piece on holding tank chemical treatments, tester Frank Lanier looks at holding tanks. For this test, he pits the Trionic holding tank against the latest polyethylene tank from SeaLand. Lanier is also located in the Chesapeake area. Judging from the pictures, the test platform for his project took up a good portion of his front driveway. All for a good cause, as they say.


Comments (11)

If you wrap the hoses with aluminim tape there will be no odors from the hoses. I have used aluminim tape on three boats over the past 15 years and it works every time.

Posted by: ROBERT E MCGHGHY | February 1, 2012 11:25 PM    Report this comment

Thanks for the great write up, Practical Sailor. Although I am running low on available product, I still have some available. The article has produced some great response and it's quite possible to see VanishOdor back on the market soon.


Posted by: vanishodor | January 12, 2012 5:12 PM    Report this comment

With many of the cures mentioning flushing with fresh water in some way, you might want to check out FreshFlush

Posted by: Unknown | January 11, 2012 6:41 PM    Report this comment

Our solution for the past four years, away from all facilities for four to five months every year, has been our "Nature's Head", Composting Marine Toilet. Our head has never smelled so clean or been so trouble free. We've met others with the same experience. No power needed other than 0.9 ma to run the integral muffin fan pushing air over our coconut coir composting mixture. No marina stops, no wharf stops, no port stops, just plain ole anchoring in Canada's paradise. Occasional pruning of the mixture and burying of some desiccated, odourless lumps OR once a month dumping of the compost into an outhouse or dug hole in the ground is the only maintenance chore -- a negligible price to pay for no more clogs, no more smell, no more annual breakdown and cleaning of a smelly toilet AND, ABOVE ALL, NO MORE HOLDING TANK !!!

Loren and Sandy, s/v SeaWeed, Fisher Northeaster 30, Canada

Posted by: loren a | January 11, 2012 6:08 PM    Report this comment

Religiously flush the head with a bowlful of fresh water supplemented by holding tank deodorant fluid. The so called white samitary hose will stink soon if you don't do this.

Posted by: Scott R | January 11, 2012 4:49 PM    Report this comment

Bucket and chuck it

Posted by: ROBERT D | January 11, 2012 1:08 PM    Report this comment

Ventilation, ventilation, ventilation. A single vent only acts to equalize the tank's internal pressure with the atmosphere; it does NOT allow effective ventilation. Keep the holding tank as aerobic as possible and odors will be minimal or non-existent. That means having TWO vent lines in each tank, with their deck fittings placed as far apart as possible, to allow continual cross ventilation of the tank.

Posted by: Edmond P | January 11, 2012 12:47 PM    Report this comment

One of the biggest culprits for holding tank order is a plugged vent line. Build up of crud in the line, at joints, and at the deck outlet is common. Occasionally the line will have a dip in it and water can gather and stand, blocking the line.

Posted by: James W | January 11, 2012 10:53 AM    Report this comment

I have a SS holding tank, and I rarely notice any odors coming from the head. The only time I every notice anything is when I'm away form the boat for a week or more in warm weather. The problem I've had is rotting sea water in the toilet bowl. To solve the problem I put a cap full of chlorine in the bow when I expect to be away for a while. This seems to kill any growth in the sea water, and keeps my head smelling sweet.

The other source of order that a lot of sailors ignore is the bilge. There the culprit is all manner of organic matter that makes its way from the table to the floor and then the bilge, but one of the worst sources of bilge odor is rotting oil that is spilled during engine maintenance. The only cure for this is vigilance, and elbow grease. Every Fall I clean my bilge meticulously with Dawn for the oil, and Sporiclean and bleach to eliminate mildew. A few years back I installed a bilge sump drain plug which I remove when the boat is on land. This prevents water that enters the bilge through the mast from building up in the bilge and freezing, but it also keeps the bilge dry and ventilated so that the source of bilge order never has a chance to grow while the boat is laid up.

Posted by: WILLIAM C | January 11, 2012 10:10 AM    Report this comment

The use of a fresh water flushing system helps a great deal in minimizing odors. Our system is a vacu-flush (there are several similar)_, and using the chemical regularly stocked at West Marine we have had no odor problems whatever.Of course, you need sufficient fresh water capacity for this,.

Posted by: WALLACE F | January 11, 2012 10:09 AM    Report this comment

Pack the area around the holding tank with kitty litter - the crystal type - it's lighter than the stuff made from clay. It is, after all, designed to absorb odor and will absorb any minor leaks. Use a shop vac to remove it at the end of the season.


Posted by: Peter E | January 11, 2012 8:37 AM    Report this comment

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