Removing SeaWater Stink

Getting Fresh Water into the Head Intake Lines

As sea water sits in a hose for long periods, between the head being used, it breaks down and starts to smell bad.   This is another kind of stink and No Fecal matter is required.  In other words, even a head with a completely empty holding tank or even one which directly discharges without use of a holding tank,  can stink.  This foul odor problem is more of an issue in summertimes as warm water temperature promotes the decay of organic matter in sea water.  Once the oxygen in the seawater is depleted by aerobic decomposition, the anaerobic  bacteria will get to work producing smelly hydrogen sulphide as a byproduct.

Flushing with the intake line with fresh water will eliminates the sea water odor problem.  One way to do this is to eliminate a separate sink drain seacock and tee the sink drain hose into the head inlet seacock. Both the sink drain and head water inlet will work fine.  When leaving the boat for an extended time, flush the head intake line using fresh water from the sink.  Just close the seacock, add water to the sink, and flush the head.

This is actually the method suggested by Peggie Hall, The Head Mistress.  A rare issue to be aware of, there could be a concern about dropping large debris in the head sink drain as it could clog the internal head pump valve.  This problem can be nearly eliminated by use of a sink strainer and/or by plumbing the drain straight to the seacock and using a 90 degree tee at the seacock for the head water inlet. In the later option, any heavy debris will fall straight out of the seacock thru-hull.

Seacocks under the head sink.  The 3/4" seacock with the white hose
supplies the head water inlet. The black hose at the 3/4" seacock above is
utilized for the sink drain.  In this photo, the 1-1/2" seacock was not utilized,
but at a later time it became utilized by the macerator discharge.

Seacocks under the head sink.  The top 3/4" seacock is closed off and not
 in use.  The bottom 3/4" seacock is tee'd to supply the head water inlet via white
hose with a straight plumbed sink drain via the black hose.  Here  the 1-1/2"
seacock is utilized by the macerator discharge (1" hose).  An option not utilized,
would be to connect the 1" macerator discharge hose to the unused 3/4" seacock
via Groco FF-750 which has 3/4" NPT threads and accepts 1" ID hose.  This
would free up the 1-1/2" seacock for a direct offshore discharge option.