The two most common sources of odor that's confined to the head are
1. If the toilet uses sea water
, micro--and/or not so micro--animal and/or veggie sea life may have gotten sucked into the flush water intake line where they have died and decayed. Black flecks in the flush water are one indication. Or, if the odor is only present with the first first flush after the boat
has sat for a few days and goes away with a bit of flushing
, it may just be stagnant sea water.
The cure: a bucket full of water to which you've added a quart of distilled white vinegar....disconnect the toilet intake line from the thru-hull (close the seacock first!)...stick it in the bucket and pump
the entire bucketfull through the toilet. It may be necessary to repeat. If you spend a lot of time in shallow water that has a lot of bottom vegetation, it may be advisable to install a strainer in the intake line.
2. A shower sump
in need of a serious cleaning
is a very common source of odor that's present only in the head. Shower
water is full of bacteria, soap scum, hair, body oils, dirt etc that can turn the sump into a stinky primordial soup, filling the head with odor via the shower
The cure: clean the sump. It doesn't have to require any manual labor...a "dose" of No-Flex Digestor down the shower drain when it can remain in the sump at least overnight, followed by flushing
it out with plenty of clean FRESH water should do the job.
A third possible source is odor from the toilet discharge line. If you haven't replaced the joker valve in at least a year, a new one will block it.
For more information, you might also consider taking a look at my book...see link in my signature here (just click on the title)...