I do put a capful of chlorine bleach in every tank of water (mine are 30 and 45 gallons respectively).
I took off the inspection
port cover on my bilge
mounted SS tank and it looks like new inside after 5 years wothout a look, so doing okay.
That said, freshwater tanks are for washing, showering, etc. we jug in our drinking water
, but are coastal cruising for now with easy provisioning
Would do same with bleach, but add filter, if going longterm and needing tank water for drinking.
I'd rather store 15 jugs of the 2.5 gallon size for drinking under vberth, settees, and in cockpit
Also have thought of making a number of large size water pipe grade PVC pipe containers (like 8-12 inch diameter x 5-6 feet long) with caps on ends. Glue in some fittings to fill and to empty. These could be stored on deck along stanchions, or in cockpit
lockers, or in pilot berths lashed down. Could fill these with known "good water" and they'd be durable and indestructible to replenish taks when needed. Anyone else think along these lines?