Testing Water quality

Water for our property is collected from our roof in a stone cisterna, so it is only used for washing, flushing loos etc.  To improve the quality of the water I have added Amuchina soluzione disinfettante (very much like Milton), which works well.Now my Dad is visiting this September and as he suffers from Alzheimer’s  it will be very difficult to get him to only use bottled water.  So I have established the correct dosing from Milton but I wondered if anyone knows of a simple water quality measuring kit that I could use? Thanks