First some comments for Dan...then some questions for Adam:
Dan wrote:
Adam,
You may want to consider plumbing in a fresh water flush for your
heads.
There are only two ways to do that without risk of polluting the potable
water: install a toilet designed to use pressurized flush water, or
install a separate flush water tank. There is no safe way to connect to
any toilet designed to flush with raw water to the potable water
system...in fact, the installation instructions for all of 'em
specifically warn against doing it.
HOwever, there's a very simple solution that solves the problem without
adding a tank, or risking an e-coli infection: tee the head sink drain
into the head intake line. To flush all the sea water out of the whole
system, close the seacock, fill the sink with fresh water, flush the
toilet. Because the seacock is closed, the toilet pulls water the water
out of the sink. You can either use this method to purge the system of
sea water, or keep the seacock closed and use the sink to flush the
toilet all the time.
I'm a liveaboard and I can tell you from experience salt water
and a holding tank can create a stench that will put you on your
knees.
Although sea water left to stagnate in a head intake can generate
horrific odor in the head, whether the toilet is flushed with fresh
or sea water makes no difference in the holding tank.
Also, salt water and uric acid will quickly cause scale to
form in the head and the lines. When I used salt water to flush, I
had to remove and clean my lines out about every 12 months. They
would become plugged with scale. A little vinegar in the head every
week helps reduce the problem but doesn't eliminate it.
A cupful of undiluted WHITE vinegar flushed all the way through the
hoses once a week prevents it for everyone else who does it
religiously...very odd that it didn't for you.
Adam (forgive me if I've already asked these questions...my email at
this time of year averages about 100 a week)...
Gray water - 1x 30 gallons polyethylene grey tank, for galley, head sink and
head shower. All "piping" with 1" Sanitation Hose, ABS/PVC fittings.
Discharge - Commercial Duty Water Puppy Model 16360-1003 Jabsco & Check
Valve + Hand Diaphragm Pump Jabsco - Seacock just above WL.
Why do you want to hold gray water? It's not required in any coastal
waters except in a few very small clearly marked areas in the FL Keys
National Marine Sanctuary where even the discharge of bilge water is
prohibited...but so is anchoring, so it's not much of an issue. At most
all you should need just about anywhere in the world is a shower sump.
Sanitation - 30 gallons polyethylene holding tank with Macerator pump Jabsco
+ Check Valve. Dock discharge through deck fill.
I'd go with a diaphragm pump...they can run dry without harm. The
SeaLand pump is your best choice. Please tell me you aren't planning to
use the deck pumpout fill to dump the tank at sea? It can be done, but
it's not recommended. How 'bout giving me more details about how you
plan to plumb this system. And why are you opting for a holding tank
instead of a Type I MSD (device that treats waste and discharges it
overboard legally)?
Head - water from sea water system - discharge to holding tank or outside
through Y valve, 1 1/2" Sanitation Hose
Two seacock 2" - one for IN and one for OUT.
2" for head intake and discharge? All marine toilets use a 3/4"
intake...head and tank overboard discharge should be 1.5". If you go
with too large a diameter, it can cause a pressure drop.
Questions: which toilette? I
didn't know that I have to many to choose from - thanks Peggie :-),
Uh-oh...it looks like I HAVE asked these questions already...
--
Peggie
----------
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://69.20.93.241/store/customer/p...40&cat=&page=1