Anti-siphon in head supply hose?

[btrayfors]

Don't forget that "above the waterline" includes at all angles of heel. If your toilet is below the waterline when heeled, you need an anti-siphon valve.

These are relatively inexpensive and easy to install.

Bill

[GBurton]

Does this mean that when you are on the throne you have to stick your head out of a deck hatch?

Originally Posted by sailingdog

That makes sense... On my boat it could never siphon... the head is mounted about six inches above the cabin sole, and the top of the head is about 10" above the waterline...and I don't heel enough for that to matter.

[bubb2]

Old and simple rule, the head sea **** is closed unless the head is being used and then closed after. and yes I checked the sea **** after each time my kids used the head.

[jrd22]

Thanks for all the replies, it makes sense to have it on the pressure side of the pump going to the bowl. Calder's book just shows it between the thru hull and head, it wouldn't work that way. The top of the bowl is above water line, except when heeled over on stb. tack so I'll put one in. I also need to install one on the discharge hose from the holding tank that goes to the macerator and then to the thru hull (the same thru hull used for the direct overboard discharge, there is a SS manifold on the thru hull). This line runs horizontally just barely above waterline and would be under water when heeled allowing water to run back through the pump and into the holding tank if the Y-valve is open to tank.

Thanks again, John

[sailingdog]

Nah, I'm short and the boat has 6' of headroom.

Originally Posted by GBurton

Does this mean that when you are on the throne you have to stick your head out of a deck hatch?

[GBurton]

Ah thats good. Must be Chuckles' boat I'm thinking of.

Originally Posted by sailingdog

Nah, I'm short and the boat has 6' of headroom.

[jbondy]

Originally Posted by jrd22

I also need to install one on the discharge hose from the holding tank that goes to the macerator and then to the thru hull (the same thru hull used for the direct overboard discharge, there is a SS manifold on the thru hull). This line runs horizontally just barely above waterline and would be under water when heeled allowing water to run back through the pump and into the holding tank if the Y-valve is open to tank.

I've never seen one in that position. The tank has a vent, so it has a built-in siphon break and the macerator acts as a check valve.