Struggling with the Evils of Marine Toilets –
09 December 2010
Coping with marine toilet chemistry. One of the unavoidable facts is that when urine and sea water mix, a type of calcium deposit is precipitated out to coat the interior surfaces of toilets and associated hoses. This deposit gradually builds up to shrink the inside diameter of hoses until you begin to notice the toilet is flushing slower and with difficulty. Eventually if no corrective action is taken preemptively, at some point it will stop flushing altogether. Of course this usually happens when something other than just liquid is to be flushed away.
'Someone' has to fix the toilet. My wife tells me this is definitely a 'Blue' job. Definitely not my favourite job! The workings of the toilet and especially the outlet hose will be found to have been reduced in capacity. Where the 1 ½ inch ID hose seemed to be overly large the deposits have only left enough room to fit a pencil. Obviously something has to be done. What are your options?
Replace toilet and hose with new.
Remove the buildup in the toilet by taking it apart and scraping it out and reassembling it.
Remove the buildup in the hose by swinging it violently against something solid like a cement driveway or driving over it with a car.
However you do it, it is a messy procedure. Is there anything to be done to prevent this buildup from occurring? There are a few things that can be done but nothing is perfect, everything is a compromise.
Take away the salt water away and no buildup. Use fresh water for flushing. This is best done by dedicating a fresh water tank exclusively to toilet flushing. However this may leave too little fresh water capacity for domestic use. Some boats have attempted to use fresh water from the pressurized water system trough a solenoid valve. This is not recommended as it may be possible to contaminate the fresh water supply.
Add an acid to the flushing water to react with the buildup and dissolve it. Some use vinegar and others go for the stronger muriatic acid, which should be used with caution. The procedure to use acid is to empty the bowl then pour in about a liter of acid, pump it into the toilet, leave it sit for 30 minutes or so, then pump just enough water through to move the acid up the hose and repeat until the acid has been exposed to its entire length. This method cannot be guaranteed to keep the system completely free of deposits but greatly extend the time between complete overhauls.
Marine toilets are a necessary evil so other than a cedar bucket which was advocated by Francis Herreshoff we are stuck with them. It is best to pamper them lest they take out their spite out on us.