Combatting Onboard Toilet Odors
Posted by Darrell Nicholson at 05:01PM - Comments: (11)
August 5, 2013
We’ve had a lot of fun with toilets and sanitation systems in the last couple of years, and after last weekend, when I descended into the smelliest brokerage boat I’d ever set foot on, I thought I’d revisit some of our findings here. The good news is that a stinky head is curable. The better news is that it need not cost you an arm and a leg. That’s not to say a cure is cheap—this is a cruising boat we’re talking about—but in many cases, a change in maintenance habits and less than $20 can put you on the path to deep breathing again.
What follows is just a brief capsule of our recent findings. For more extensive reading, I recommend checking out the full versions of the articles cited below, or one (or both) of the following sources: Peggie Hall’s “Get Rid of Boat Odors” or Volume II of our two-part eBook on marine sanitation.
Odor control doesn’t necessarily start at the marine head (hoses are often the chief culprit), but that seems like the logical place to start. A big step toward reducing head odors is to use fresh water for flushing. Salt water is alive with microscopic critters that add to the odor problem when they die and decay in your holding tank. That is not practical for most long-term cruising boats, but the owner of a big boat with extra tankage can get by with a freshwater flush, particularly if he uses a vacuum-flush toilet system like those we tested in 2011.
The newer electric toilets we tested also cut down on water usage, and just as importantly, they help clear the hose better with their high-velocity flushes. These heads use a high-speed centrifugal “Vortex” pump, which has a unique convex rotor and a funnel-shaped casing or volute that converts kinetic energy into pressure. Akin to a common bilge pump, the centrifugal pump has a set of curved blades on a rotor. The fast-spinning rotor creates a change in pressure that can quickly push a slug of liquid through the system, using very little water and making far less noise than the earlier renditions.
Whether you use fresh or salt water, you will still want to control the chemistry in your holding tank. At the end of last year, we tested several holding tank additives that are effective at controlling odor. Among the products we tested were a few that seemed to help control odors right at the head, and these products would also be effective for portable toilets.
However, you have to be wary about what you add. Our recent test of joker valves—the essential valve that prevents backflow from the holding tank and helps create the vacuum for flushing—demonstrated that some products used for cleaning, deodorizing, and winterizing heads can shorten the valve's life. If you’re serious about controlling head odors, you will watch what you put in your head and replace this valve every year. It is the most important valve in the system.
But to get to the bottom of most head odor problems on older boats, you need to look at the plumbing. Head odors can easily seep through cheap hoses. We conducted a series of tests on two vital hoses—the marine sanitation hose between the head and the holding tank, and the vent hose between the holding tank and the through-hull vent fitting. One of my previous blog posts describes some tips for eliminating hose odors. And finally, we tested holding tanks and holding tank sensors, those trouble-prone devices that tell us when it’s time for a pumpout.
Too often, sailors accept head odors as an inevitable side-effect of having a holding tank. But with a little extra effort you can escape the stink.