Drinking Water (ASCE 2009 Grade: D-)

Public water supplies must meet the demands of residential, commercial, institutional, and industrial users. Water must be delivered to homes such that residents always have safe drinking water at an appropriate pressure. The same system that treats and distributes the drinking water to homes must also meet the pressure and quality needs of the non-residential users. Perhaps most importantly, this system must be able to supply large quantities of water for firefighting purposes.

Typically, the entire water supply distribution system carries water that has been treated to drinking water standards, even though less than 1 percent of the water is used for drinking. As drinking water standards become more stringent, the cost for treatment escalates. Some communities have implemented, or are considering the implementation of, separate water systems, whereby some users (e.g., industry and landscape irrigation) are supplied with water that is not treated to drinking water standards. The cost of savings from lack of (or less thorough) treatment must be weighed against the capital, operation, and maintenance costs of the additional infrastructure (i.e., a “second” water distribution system).