Head pump

Mike Ondra <mondra@...>

We are persistently getting backflow of waste water through the check valves
back into the toilet bowl, enough sometimes to fill the bowl. Besides being
unpleasant at anchor, this can be a mess under sail. I would presume (and
hope) this volume represents the waste water from the riser tube only and is
not siphoning out of the holding tank somehow leaking back through the
tricuspid check valve as well as the flapper valve in the pump assembly.
New valve and flapper seemed to retard the problem for a short time only.

Does anyone know what the riser tube looks like inside the holding tank.
Does it simply extend to near the top of the holding tank with an open end
inches below the top of the tank? Or perhaps there is a 180 deg elbow on

Have other faced this and discovered the problem and solution?

Mike Ondra
Aletes - SM 2000 #240

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