Holding tank vent line(s)

I am having my new holding tank and head completed this winter and I was wondering if anyone had any thought about the following:

In Peggie Hall’s article, http://boatbuilding.com/content/sanitation.html , there is an interesting discussion in there about using two holding tank vent lines for increased airflow (in order to keeping anaerobic bacteria in check). Has anyone done this and/or what do people think of this idea?

Also, is there a de facto place for the vent thru-deck on the BCC?


Peggie Hall’s idea is very sound. The setup does require a means to pump a small stream of air into the black water via a sparge tube fitted near the bottom of the holding tank. I like the idea but it does add another level of complexity to the holding tank.



We installed the new Ronco 13 gallon model 125 waste tank under the samson posts a year ago, actually had to cut the post shorter, build a retaining bulkhead and and make new deck hatches to cover the chain locker.

We installed the thru-deck waste pump-out fitting just aft and to port of the port side samson post, it drop the hose directly down to the stand tube on the tank.

A simpler approach to getting more air to the waste is to install a larger vent hose-1" and thru-hull fitting.

Hi, Paul,

I hate holding tank odors and our boat is our home. I thought Peggy Peal made a lot of sense, so when we set up Galatea’s holding tank system, we spec’d a tank with two 1.5" vents and put a bronze thru hull port and starboard in the walestrake. They’re nicely green now and don’t seem obtrusive to me, and I haven’t had any lookers ask about them.

We did find that, especially sailing hard to windward offshore (in big waves), the lines would fill the tank, so I fitted valves to close the vents when we’re at sea. Otherwise, we have excellent ventilation and so far, no odor problems.

SV Galatea