Total Coliforms are a group of bacteria that are commonly found int the soil, water, and the digestive tracts of humans and animals.
E. coli  is a type of coliform bacteria. When drinking water is positive for coliforms, the lab will also test for E. coli, which is harmful for humans to drink and eat.

When well water is positive for bacteria, it should not be used for drinking or cooking. The well should be chlorinated as soon as possible to clear out the bacteria from the system.

Nitrates are chemicals that are commonly found in vegetables. plants, and groundwater.

When well water has a nitrate-nitrogen concentration of more than 10 mg/L, it is not safe to drink or eat. It is especially dangerous for pregnant women and babies. Nitrates can cause birth defects, "blue baby syndrome", and thyroid disease. The well should be inspected by a license well driller, who will develop a plan to lower nitrate levels in the well water.