Forgive me (or direct me) if this has been hashed out previously, I searched but did not see any obvious examples.

I bought a 250 gallon bladder for drinking water (military surplus)and am curious what should be added to water for long term storage. The bladder is about 48" diameter and 6' tall. VERY thick flexible rubber and was originally used for drinking water. It has SERIOUS clevises and brass flanges and standard pipe fittings for use. It is designed to be lifted from the clevises, I may make a steel "pallet" to hold it.

Any thoughts on treatments?

Thanks Ironwood