I thought this may be of interest to those who have onboard/builtin water storage tanks if anyone. It’s from Practical Boat Owner. I read it as I regularly sterilise my motorhome tanks and I was interested in his procedure. I use Milton, have done for years and even though I only have plastic portable water tanks in Spritzig II they get the Milton every haulout. All my tanks, boat and mh only get potable water in them but do sit sometimes for a while and have multiple sources. I use white food grade hoses.
No idea if it’s correct but a read years ago that if your travelling, road or boat it better to drain your tank, rinse if practical and refill from new source as bacteria from different water sources are not necessarily compatible. I think that’s not probably an issue with treated town water these days but I do it when I can and Milton after topping up at multiple locations. Anybody out there a scientist?