recently changed our manual Jabsco head from salt water to fresh water and now have it piped to get the tap water to flush it.
A
very bad idea unless you installed separate flush water tank to feed it because toilets designed use sea water have no built in protections against contaminating your potable water supply with sea water and/or bacteria from the bowl. ONLY toilets designed to use onboard pressurized flush water should ever be connected to the fresh water plumbing. Please don't say "we never drink the water from our tank"...'cuz you don't have to drink any to ingest a lot more of it than you think you do. You wash your hands in it, then pick up a sandwich...you rinse out a glass or a cup, then fill it with the "safe" bottled water...wash dishes in it, brush your teeth in it, and even get it in your mouth and eyes when you wash your face or shower.
However there is a safe way to supply fresh water to the toilet that doesn't involve tapping into the fresh water supply: reroute the toilet intake to tee into the head sink DRAIN line. The tee needs to be below waterline, as close to the seacock as possible. This allows you to flush with sea water, then rinse it out of the system before the boat will sit in the summer heat (which is when the sea water trapped in the intake, pump and channel in the rim of the bowl stagnates and stinks!) After you've closed the seacock (you DO close all seacocks before leaving the boat?), fill the sink with clean fresh water water and flushing the toilet.. Because the seacock is closed, the toilet will pull the water out of the sink, rinsing the seawater out of the WHOLE system--intake line, pump and channel in the rim of the bowl (water poured into the bowl just rinses out the bottom of the pump and the toilet discharge line). Or, you can flush with fresh water all the time, by keeping sink drain seacock closed except when using the sink and filling the sink with clean water. A lot of boat owners have done this and love it.
Now to your toilet problem: I don't see how any y-valve could cause your problem unless you've added a y-valve to the intake line to let it alternate between fresh and sea water, there shouldn't be one in the intake (and it needs to come out!)...nor in the toilet discharge line unless you've plumbed it to go overboard or into the tank. Otherwise, the only y-valve should be in the TANK discharge line, to provide a choice between pumpout or dumping the tank at sea. Hunter used a tee fitting instead (because they cost less than y-valves), but a tee fitting doesn't provide any way to shut off the flow of waste from the tank if you have to work on the macerator pump--something no one ever finds out they have to do when the tank is empty.
So I strongly suspect the problem is a blocked tank vent. When air displaced by incoming flushes has no way to escape, the system becomes pressurized, creating back pressure that makes the toilet increasingly harder to pump and causes backflow into the toilet. So don't us the toilet again or attempt to pump out until you've cleared the vent or made sure it isn't blocked. The two most common locations for a vent blockage are the VENT thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Start by using a screwdriver blade, ice pick--whatever works--to scrape out the thru-hull. If the tank is seriously pressurized, that may result in a spew if the thru-hull is the only block. If cleaning the thru-hull doesn't solve the problem, you'll have to remove the vent line from the tank and scrape out that end of the hose and the vent fitting in the tank. BUT BEFORE YOU DO THAT, open the deck pumpout fitting to relieve any pressure in the tank! And have a hose at the ready. If the toilet hasn't been used in several days, the pressure may have dissipated, so don't assume that blocked vent isn't the problem just 'cuz the tank is no longer pressurized.
Or your problem could be as simple as... when, if ever, was the last time you lubricated the toilet pump? Toilets can get very hard to pump without any lubrication in 'em. If you do keep it well lubed, Jabsco toilets are known to have other problems.
You really NEED my book (see link in my signature below)...the title (my publisher's idea) is a bit misleading 'cuz although it does deal with every source of odor on a boat and how to cure--better yet, prevent--'em, it's actually a comprehensive "marine toilets and holding tanks 101" manual that will help you learn how to cure--and better yet again--PREVENT 90% problems instead of having to cure 'em...'cuz you get to do preventive maintenance on YOUR terms when it's convenient...cures are never needed when it's convenient! And I'm always glad to answer any questions it doesn't.
--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
