Water Treatment Plant No. 2

History & LocationTreatment Plant deck

Water Treatment Plant No. 2 (WTP2) was placed in service in 1993. It is a conventional ozone plant used to treat water delivered via the South Bay Aqueduct. It is located on Mission Boulevard near the I-680 interchange in Fremont.


WTP2 uses the following chemical additions: carbon dioxide to lower the pH of the raw water for process stabilization and bromate control, chloramines pre-ozone to maintain low bromate levels, ozone as a pre-oxidant, and ferric chloride or alum as a coagulant. There are two separate process trains consisting of six flocculation basins, four sedimentation basins and six dual media filters with post-filter addition of chlorine, ammonia, fluoride, and sodium hydroxide

The maximum design production rate at WTP2 is 28 million gallons per day (MGD). However, this production rate is reduced due to recirculation of some process flows and reduced output when filters are off-line for backwashing. As a result, the sustainable production rate at WTP2 is 26 MGD.