The following is the position of the Santa Cruz Desal Alternatives group on potable use of recycled wastewater.
There are several serious drawbacks to Direct Potable Reuse (sending treated wastewater directly into the potable water distribution system) which should negate such an idea as a primary strategy:
1. Energy Use: The energy consumed by the treatment process is estimated to be approximately four times that of our current water supply. The treatment plant would run continuously—even when water in the river is plentiful.
2. Cost: The product water is the highest cost water (both capital costs and operating costs) short of desalination.
3. Health: There is credible evidence from independent scientists that trace amounts of endocrine disruptors and other contaminants of emerging concern present even in recycled water produced by state-of-the-art treatment plants may be harmful to public health.
Because of these drawbacks, Desal Alternatives recommends that Direct Potable Reuse be considered as a last-resort backup water supply strategy if and only if all of the following conditions were met:
1. The public health risk of Direct Potable Reuse were proven negligible based on current reliable science regarding the health impacts of consuming low doses of endocrine disruptors, engineered nanoparticles, and other contaminants of emerging concern. This is an application of the Precautionary Principle.
2. The City water service area were at risk of a water supply shortfall that would impact health and safety (i.e., the risk of economic impact of a supply shortfall is not a sufficient reason for adopting DPR.)
3. Recovery of the aquifers by use of river water were proven infeasible for meeting a supply shortfall that threatens health and safety.