Screening questions for evaluation of a well used for drinking water:
(1) Are there several persons using the well water who are ill?
(2) Is the well located at the bottom of a hill?
(3) Is the well relatively shallow?
(4) Is the well located near where animals live or graze?
(5) Are the well casing cracked?
(6) Is the well poorly constructed?
(7) Is the water treated prior to drinking? Is the treatment adequate to make the water safe?
where:
• A well located at the bottom of a hill is more likely to be contaminated by rainwater runoff. This could be significant if animals graze or live on the hillside.
• A shallow well is one that is more likely to be contaminated by floodwater or rainwater runoff. It is also more likely to be contaminated by animal waste seepage. There may be several mechanism operating here. First, a deeper well would have more filtration and the conditions would be more likely to kill enteric bacteria like Salmonella. Second, a shallow well strikes me as indicating land that is or could become easily marshy.
NOTE: Most of these factors would also indicate a well likely to be contaminated by pesticides or environmental toxins.
