Holding Tank Plumbing Diagram

[Dame.n.Jess]

Hi All

I'm about to add my holding tank to the boat and I want to get some opinions on my plumbing diagram.

I have never plumbed up a marine toilet before but I figure with a good diagram it can be to hard, I am not sure it I need to have anti sifon valves at the top of my above waterline loops or if the loop on its own is enough.

Any feedback would be appreciated.

Regards
Damien

[Dame.n.Jess]

Bump up

[Blue Stocking]

Have you searched around the forum? Afew weeks back, this subject was extensively covered. IIRC, GordMay presented detailed diagrams.

[Mike Vogdes]

The West Marine catalog has a very helpful element called the West Adviser, which is a section devoted to helping the customer design the most appropriate system for their boat. For major components such as a holding tank and all the associated pipe, valves and fittings, the West Adviser gives recommended holding tank designs complete with good drawings. Just pick up a catalog at West Marine and thumb thru the plumbing section.

[AnchorageGuy]

This is a typical installation. Chuck

[JPGPipes5]

I don't own a cruiser, but I love sailing when I'm anywhere near a coast. Here in Indianapolis, I own a house boat that I spend most of the summer on. Some Indianapolis plumbers and myself installed a new toilet on my house boat recently, and our setup looked almost identical to the diagram in the post above me.

Hope this helps!

[peghall]

I'm not a big fan of "one size fits all" sanitation plumbing diagrams, 'cuz in my experience they rarely fit just ONE situation, much less all.

If you'd like to email me I'll be glad to help you spec it out. Hopefully you haven't bought the tank yet, 'cuz where to put it matters, so it needs to fit the right space.

A good rule of thumb to start with: the tank should be within 6' of the toilet. Reason: that's as far as bowl contents will travel in the amount of time anyone is likely to spend pumping a toilet...and if it doesn't get to the tank, it's left sitting in the hose to permeate it. However, there are work arounds that can incorporate some help from gravity. And yes, you will need at least one vented loop (antisiphon device)--in the head intake...and where IT goes matters.

[HopCar]

Waterwayguy has a good diagram. Note that both loops are vented with anti-syphon valves. Also note that the loop on the intake side is between the pump and the bowl. If you put it between the thru-hull and the pump, the pump will be sucking air every time you try to flush. There is no point in having a loop without an anti-syphon vent as water could just syphon back over the loop and flood the boat. You need air to get in the line and break the syphon.
I have my system set up so that everything goes into the tank. I have no option for direct discharge as I'm almost always in a no discharge area. I can empty the tank through a deck fitting or, when legal, empty it overboard with a macerator pump.
I see Peggy has posted while I was writing this. You can't go wrong consulting with her. You should also buy her book.