So how does the San Joaquin Valley’s water quality rate? Not very well for drinking. Nitrate contamination is a very real concern. What can you do? Pretty simple, you can purchase a water filter and it doesn’t have to be expensive. Most of the lower cost water filters will filter at least 60% of nitrates. Is that enough for Stanislaus County water, to remain below the 10 ppm? Here’s a report of not only water quantity, but quality for this part of the Valley created by Modesto Irrigation District – skip to pages 64 – 85 to determine what you should be doing.