Can having a deep well increase the probability of obtaining low nitrate ground water?
Yes. In areas with a high probability of nitrate in ground water greater than 2 mg/L, wells drilled deeper can increase the probability of obtaining water with low nitrate concentrations. For a 90-percent chance of obtaining low nitrate ground water, wells installed in the agricultural areas of eastern Washington generally would need to be drilled to a depth of at least 750 feet. Likewise, wells in the urban and agricultural areas of the Puget Lowlands would need to be drilled to a depth of at least 400 feet.
