Gravity holding tank does not drain

[BarryL]

Hey,

I don't think that gravity alone will work well. I would install a macerator pump on the output of the holding tank to the overboard discharge. When you are in an area will legal dumping of the holding tank it will take only a few minutes to empty the tank.

Barry

[treilley]

Originally Posted by mitiempo

The ideal way to install a gravity drain holding tank is with the deck pumpout fitting directly above the seacock so you can clear a clog easily with a rod from on deck.

That would not work for me as the clog I had was at the output of the tank not at the seacock.

[mitiempo]

Ideally the deck pumpout fitting goes straight down into the tank and the gravity drain is directly below that vertically to the seacock. A straight line from deck to through hull. They work well especially if not filled with paper or at least if biodegradable paper is used.

[malaspina]

Thanks for all the posts and suggestions! I believe a macerator pump would solve my problem if it could be mounted at or very close to the tank, but if its a few feet downstream I'm worried it might not prevent or clear a blockage from occuring further up. I'll have another look but don't think there's any way to mount a pump close to the tank without major surgery. That may lead me to the electric head option. Thanks again!

[Minnewaska]

Something else to consider. Electric macerating heads take substantially more water to flush properly and clear lines. Therefore, they use up space in the tank faster. We have them and wish I had vacu-flush instead. Too expensive to retrofit now.