My experience so far suggests that it won't stay in the tank long enough to go bad if it is supplying two toilets and a washing machine and is filtered VERY well before entering the tank. (10 micron steel mesh followed by a 1 micron filter bag). I've been adding the odd bit of chlorine tablet but knowing how much to use is a bit of guesswork.
On the other hand, Mrs Pontiff insists that I come up with more data before I connect the washing machine up.(We're having a brand new child delivered next week so Health and Safety head has been engaged).Microbe levels are much lower than I expected ( without the Cl tablets) according to my Year 8 class who have been tasked with analysing samples on a weekly basis.
I'm maybe looking at a 25w uv inline steriliser on the input pipe to the washing machine-not cheap but will pay for itself by April 2239 so thats ok.

(I also spent £13 grand or so on the pv system to power it so no worries there)

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