I have recently had to replace the Y valve which diverts waste water to the holding tank or overboard. The lines are caked with salt. I wondered if there is a simple way to dissolve or flush the lines without replacing them.
Advice from Peggie Hall that I found in the archives.
Terry Cox
Her advice follows:
The mineral buildup in your hoses is not a mix of uric acid and water...the minerals are salt and sea water calcium carbonate, and can occur in ALL raw water intake hoses, not just sanitation hoses...so check your engine intake and exhaust hoses and clean them out if necessary. The mineral content in warm sea water is much higher than it is in cold water, which means that buildup will occur much faster in warm waters than in cold.
Muriatic acid will dissolve it...and distilled white vinegar WILL prevent it when used correctly. Use ONLY distilled white vinegar, never cider or any other kind...white vinegar is made from distilled alcohol and is more acidic--and therefore more effective--vinegars made from fermented fruit juices. A cupful flushed through the hoses once a week before the boat will sit will prevent build up. Do NOT leave it sitting in the bowl...that accomplishes nothing except a ruined joker valve. Geoff says he uses vinegar "regularly," but doesn't say how often 'regularly' is, which type of vinegar, or how long it stays in the system before toilet use flushes it out. But used correctly, it DOES work!
Geoff, your friend is right that fresh water does eliiminate SEA water buildup in hoses...although some fresh water has a high mineral content that can result in "scale"...but much more slowly. However, I hope your friend has not connected a sea water toilet to his fresh water plumbing, 'cuz that's a BIG no-no! It cannot be done without risk of e-coli contamination of the fresh water, damage to the toilet pump or both...and EVERY toilet mfr. specifically warns against it in their installation instructions. There are only two safe ways to supply fresh water to a sea water toilet: a separate dedicated flush water tank that shares no plumbing with the fresh water system, or the head intake line connected to a sink drain. (I'm not sure exactly what sailingdog means by "the sink acts as a separator"....it's considerably more simple than that: sink drains are not connected to the potable water supply.)
While it's not really necessary to use fresh water to eliminate sea water mineral buildup, nor replace hoses to clean it out (beating 'em on the dock will get rid of 99% of it), does have the added benefit of eliminating sea water odor problems. But just flushing all the sea water out before the boat will sit solves that problem and the correct use of white vinegar will prevent the buildup.