Hi birdsey! sorry for the delay in response! Yes it was under the head sink base! This made it so there was only room for some cleaning bottles to the center of the boat. The unit worked great! I had the effluent checked. The problem is, that unit is not is not legal according to the E.P.A.. What a surprise! If owners were made to make sure they worked, imagine the possibilities! Ours' always worked well, through diligence, in maintenance! We have gone to a porti potty! The units if maintained would make the effluent totally neutral(ie. fish food). Anyway there are obviously larger powers at work!!!!

Mike d. I saw your post about the Lectra San unit being "removed from the sink base" on the GS 37. Do you mean the treatment tank was UNDER the sink?

Thanks, in advance

Garth