The acid test for descaling boat toilets

Referring to Chris Mardon’s suggestions (‘Scale back on outlet pipes’, PBO August), I believe that there is a far easier and more certain way of descaling a toilet system.

While in Gibraltar 20 years ago, our Blakes toilet was truly furred up. The outlet loop was in 38mm copper pipe (the boat was built in 1964), and I had dismantled it and laid it and the Blakes pump out on the quayside. While I futilely attempted to rid it of scale, a Swedish sailor passing by told me to go and get some ‘Aqua Fuerte’, which turned out to be a 25% solution of hydrochloric acid, with which I was not too keen to fill my toilet. It could be bought off the shelf in Spain in those days, ready-diluted.

However, being persuaded that it would do no harm,

I went ahead and filled the outlet loop (propped up in a ‘U’ shape). After several hours this was emptied and, lo and behold, it was as clean as new. I reassembled the system and then filled the toilet bowl with Aqua Fuerte, and drew it into the pump. After an hour or so I pumped in seawater to flush out the pump, and again, this was like new. The acid cleans out valves etc that mechanical descaling could not touch.

Since then we have used 25% hydrochloric acid on several systems, with excellent results. Warning: do not spill onto stainless steel, as it will mark (but not damage). The job can be carried out with the system in situ, but the outlet pipe must be emptied of water to allow the acid to fill. This is easier during a lift-out, but do catch the effluent when emptying finally. Twenty-five per cent hydrochloric is not dangerous with sensible precautions (goggles, rubber gloves, etc), but importantly, do add the acid to water – NOT water to acid, as this can cause a violent reaction.

Hope this may be of help to someone in toilet distress.