Water from rivers and reservoirs can contain a variety of organisms and inorganic material that must be removed before the water is safe for drinking and other uses. Larger particles such as sand, vegetation and other materials must be screened out first. Smaller particles are removed as water is drawn through very fine pores in membrane fibers. The pores are just large enough for water to pass through, but small enough to leave behind contaminants and particles, such as dirt, dust, bacteria, cryptosporidium, giardia, and others. Contaminants that do pass through the membranes are eliminated in a disinfection process in which a long-lasting disinfectant keeps water safe and healthy as it travels through pipelines to reach homes and businesses. In addition, as part of the treatment process, fluoride is added to the treated water.
The Water Authority selected the submerged membrane method because it is safe and highly effective in producing high-quality treated water. The membrane treatment, in conjunction with the other processes at the plant, has such a high degree of contaminant removal that the plant is able to meet increasingly rigorous state and federal water quality regulations.
The Twin Oaks Valley Water Treatment Plant is a project with many benefits beyond the high-quality water it produces. Its strategic location, creative design, and use of membrane technology make it an efficient, money-saving facility. Nearly all water entering the plant leaves as high-quality drinking water.