How to clean a soft water cistern - holding tank?
We have a 10 year old, buried, soft-water cistern. It is made of opaque white plastic and hold 1000+ (?) gallons. It is quite large. It holds collected rainwater from a residential home. This water is used in the house in toilets and in soft water taps. It is installed in a new house, in a rural setting. Occasional bleach is used. I suspect the tank needs a good purging and/or drainage at this point. A prematurely aged and failed shingle roof was just replaced. These were infamous "organic" shingles, no longer made. The water is brown. The volume must be low right now as it has been very dry this summer. How is this set-up properly maintained? Thank you