macerator discharge plumbing

[gettinthere]

My old boat was set up with an overboard discharge underwater thru-hull direct from the toilet. Later added a Y-valve to a holding tank and a deck fitting for pumpout.

Can I add a macerator to the holding tank and plumb it's discharge to the underwater thru hull? If the manual toilet can push waste down thru the hull, couldn't a macerator? I'd like to avoid adding another hole in the side of the boat hull for a macerator discharge.

And yes, this will only be used 3 miles offshore ocean.

 

[Chuck Creel]

my boat has that and yes it works..just need another y vavle

 

[Joe]

Move the y valve to the exit side of the holding tank so the head discharges directly to the tank. Install the macerator pump in the overboard discharge line between the y valve and thru-hull. The other y valve line goes to the pump out fitting.

 

[Peggie Hall HeadMistress]

What I would do instead...

The simple answer to your question is yes...you can tee a tank discharge into the same thru-hull as the toilet direct discharge. But I'd do it a bit differently than Joe suggests:

If you'll be far enough offshore in open ocean to dump a tank, you'll be far enough offshore to flush directly overboard...so why send everything to the tank, requiring you to deal with dumping it when it gets full, regardless of weather conditions? Leave the y-valve between the toilet and tank in place...then eliminate the need for a second y-valve by installing a second discharge fitting in the tank. That's very easy to do, thanks to a li'l gadget called the Uniseal UNISEAL (Scroll through all the pages to see how it works and the prices).

Since it's likely that the pump may go through long periods of DISuse, I wouldn't go with an impeller macerator pump...too failure prone when they're allowed to sit. I'd go with a manual or electric diaphragm pump instead. Mount it well above the tank and you'll be able to get away without a vented loop after the pump.

However, I wouldn't do any of this until you're ready to "hit the road" for salt water...sitting unused for long periods doesn't do any equipment any good.

And btw...when you do get to salt water, you'll have to start dealing with odor from stagnant sea water in the head intake...so when you do this project, it would also be a good time to reroute your head intake line to tee into your head sink drain line to provide a means of rinsing all the sea water out of the system before the boat sits.

 

[Joe]

That makes more sense to me also, Peggy. I can pump directly overboard with my current set up... I chose the wrong WM Advisor diagram, obviously, forgetting how important the dilrect overboard featurel is... especially if you're cruising.. there's no point filling and emptying the holding tank if it isn't necessary. A manual diaphram pump would be my choice... the less power used the better.

 

[gettinthere]

Peggy

I'm thinking Joe's way makes sense for me. I can be in a no discharge zone and flush to the holding tank. Then I have the option of going offshore and discharge the holding tank or get a pumpout.
With your method, it sounds like I will need another thru-hull for holding tank discharge, or did I misunderstand you?

 

[Peggie Hall HeadMistress]

Nope...no other thru-hull needed

Did you read the first sentence in my previous reply?

The only differences between Joe's plan and mine are the location of one y-valve and MAYBE a new discharge fitting in the tank to eliminate a second y-valve in the tank discharge line.

 

[Joe]

Peggy, kind of like this.... but, without so many y-valves?

 

[Peggie Hall HeadMistress]

Yep...kinda like that, except...

Two discharge ports in the tank instead of one with a y-valve....and the pump mounted above the tank.

Ideally, ALL the fittings would be in the top of the tank, with pick up tube(s) inside the tank for the discharge(s)...but that requires at least 5" clearance above the top of the tank, which isn't always possible.

Oh...btw...you need one more vented loop--in the intake, installed between the pump and the bowl.