The USGS is researching the use of reclaimed water (treated municipal waste water) for irrigation is being proposed as a way to expand limited water supplies throughout southern California. Citrus and avocado growers are concerned that elevated concentrations of boron, sodium, chloride, and surfactants in the reclaimed water could adversely affect their orchards. The scientific literature contains conflicting reports of either the safety or the hazard of reclaimed water on citrus and avocados. In addition, there has been a long-standing misinterpretation of the guidelines for boron in irrigation water, suggesting that reclaimed water may not be as safe as is often believed. The effects of water quality on tree health are also dependent on irrigation management, soil mineralogy and texture, tree variety, rootstock, and climate. In this work we propose to evaluate the effects of reclaimed water on the physical properties of S. California citrus soils, and the toxicity of reclaimed water to navel orange trees (Citrus sinensis). This work will determine the relative safety of using reclaimed water for irrigation of citrus. - Millet

Yes, there are some studies, that municipal waste water is full of drugs, especially remants of contraception substances, etc. But in fact, the most dangerous water for human kind is water, which come to river from agricultural fields via surface and underground flows . I saw horrible tv document from France about contamination of rivers by pesticides, fungicides, fertilizers and many other drugs used in agricultural production.

Human immigration to mild-climate zones and
concomitant urban development competes with citrus for both land and
water resources. This trend began in Southern California and is now also
evident in the citrus producing areas of Arizona, Texas, Florida, and the
Mediterranean coasts. The requirements for high-quality water will ultimately
require citriculture to depend on alternate poorer-quality
water sources, including recycled waste water and even brackish water.- Millet

Future big wars will be the wars for drinking water resources .