bleach tablets

[Lightspeed]

Milton tablets. get them in most supermarkets.

Simples

Used these in the tropics to clean out water storage tank of a house that used to be left empty while we were away for periods of up to two years. Imagine the sort of nasties that can multiply in permanently warm water in that time:-(

Upon arrival first job was always to drain the tank and let it refill. Once refilled a handfull of milton tabs thrown in and left for an hour or so till all disolved then systematic opening of all taps in the house until chlorine smelling water was flowing.

Over a period of several decades we never picked up any nasties from the house water supply.

These things are very effective.