Just a note to suggest other 440's check their watermaker
was earthed when installed.
We recently noticed two pin size leaks
when our Idromar system was run.
It turned out that the end caps of the long stainless steel
vessels were suffering electrolysis
between the tube end caps and the actual membrane housing tubes .... because it was never earthed when originally installed !
Fortunately, our repairer was able to make a series of layered / custom seals
to get a suitable pressure seal instead of having to replace the two pressure tubes (which was going to cost many more boat units (ie thousands) if the new seals
didn't work!) ..... and earth it properly !
We're probably not the only ones so suggest adding this to your "things to check" list.