Rod McInnis wrote:

If you can locate the tank lower than the toilet, you will be MUCH happier
in the long run!

Not necessarily. If the head is to be flushed directly overboard at sea,
it's necessary to install a vented loop at least 8-12" above the
waterline at any angle of heel, which on most boats would put it above
the tank...so as long as the tank isn't higher than the top of the loop
it doesn't matter.


Pumping the tank overboard (in legal areas) is not a big issue. The pumps
are fairly reliable.

The toilet is not so reliable. If the tank is higher than the toilet, I
would fully expect the contents of the line to the tank to leak back into
the toilet bowl.

It doesn't have to... any manual marine toilet that's working even close
to factory specs can move bowl contents/flush water up to 6'...so if the
toilet is flushed long enough in the dry mode to clear the top of the
loop, there shouldn't be any runback.

If you do this, I certainly hope that the line from the
toilet attaches at the top of the tank so that the entire tank can't empty
back through the toilet!

Amen to that!


Eventually you will have to work on that toilet, which may mean that you
will have to remove the hose between the toilet and the tank If it is
uphill to the tank, you will have a hose full of crap spill out into the
head.

Since anyone with enough sense to rebuild a toilet as preventive
maintenance instead of only fixing what breaks would run a LOT of clean
water through the toilet before disconnecting any hoses, any runback
SHOULD only be flush water...but there shouldn't be much of that. And
there'd be the same amount if there's a vented loop in the line.

All that said, I would definitely recommend that the tank be below the
top of the loop...but the loop provides a bit more flexibility in
selecting a location based on height.

Peggie
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Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html