Zone 7 Water Agency has begun operating its new demineralization plant on Santa Rita Road, just north of Stoneridge Drive.
Through reverse osmosis, the plant reduces the hardness of groundwater pumped from wells that's supplied to the western part of Zone 7's service area, in Pleasanton and Dublin. It will be especially positive for those who live on the western end of the water agency's service area, which is where that water is primarily delivered.
The facility can remove minerals from up to 7.7 million gallons per day of groundwater, according to Zone 7 spokeswoman Boni Brewer.
"In the long term, all Valley residents will benefit from the plant's operation because salt removal from the groundwater basin will facilitate regional recycled water projects for irrigation use, thereby enhancing the Valley's overall water-supply reliability," Brewer said. "This is especially important in light of continuing concerns about the long-term reliability of supplies conveyed through the ecologically fragile Delta."
Hard water is safe for drinking, cooking and other household uses. However, a high content of calcium, magnesium and other minerals in groundwater over an extended period of time can shorten the life of plumbing fixtures and appliances, leave white spots on cars and dishes after washing and require more soap and detergent for laundry and other cleaning, Brewer said.
The actual mix of groundwater and surface water that reaches a particular customer's tap varies for a number of reasons. Under normal conditions, Zone 7 delivers surface water to southeast Pleasanton and Livermore. But depending on the time of year, it provides both surface water and groundwater to other parts of Pleasanton and to Dublin San Ramon Services District. More groundwater is pumped during dry or drought periods, summer peak demand or when water-treatment facilities are closed for maintenance. In addition, the City of Pleasanton operates its own groundwater wells to add to Zone 7 water supplies, which are not treated by the demineralization plant.
Some residents will see more of a change than others, Brewer said. In general, softened water will be served to about 20,000 homes in Pleasanton and Dublin for approximately nine months per year as a result of this project, she added.
The Mocho Demineralization Plant cost $35.6 million to plan, design and construct and is funded by water rates, connection fees on new development and a $740,000 Proposition 50 state grant. It will cost an estimated $1.5 million to operate it for the nine months planned each year.