If your well has a vent, be sure that it faces the ground, is tightly connected to the well cap or seal, and is properly screened to keep insects out. Well Age Well age is an important factor in predicting the likelihood of high nitrate concentrations in drinking water. In Indiana, a sampling of private wells showed a correlation between well age and depth and nitrate concentration. A well constructed more than 70 years ago is likely to be a shallow dug well and probably surrounded by many potential contamination sources. Older well pumps are more likely to leak lubricating oils which can get into the well.
Older wells are e also more likely to have thinner casing that maybe corroded.
Even well casing that is only 30 to 40 years old is subject to corrosion and perforation. If you have an older well, you may want to have it inspected by a qualified well driller. Well Type Dug wells pose the highest risk of drinking water supply contamination because they are shallow and often poorly protected from surface water. They are constructed by driving assembled lengths of pipe into the ground. They can only be installed in areas of relatively loose soils, such as sand.