Water that looks and tastes good may not necessarily be safe to drink. If you get your drinking water from a well or other private supply, the only way to tell if it is safe is by having it tested at a certified laboratory.
The Environmental Protection Agency (EPA) recommends that you monitor your supply at least once a year for E. coli. View guidance here
The EPA consistently reports that the quality of the water in private supplies is not as good as that of public supplies. For example, it is estimated that between 15% and 30% of all wells are contaminated by the bacteria E. coli. Bacterial/microbial contamination can come from badly managed septic tanks, slurry spreading or animals being allowed to roam too close to the source.
Symptoms of contaminated water may include frequent upset tummies, diarrhoea, blue baby syndrome, high blood pressure and heart conditions.
Or, if the contamination is chemical, there may be problems around the house such as leaking copper fittings, having to replace your dishwasher or copper heating cylinder, discolouration of hair or laundry and green/blue stains on sanitary ware.