DUBLIN -- Purple pipes are on their way to central Dublin and will bring much needed relief to the Tri-Valley's water supply.

The Dublin San Ramon Services District board approved a $2.1 million contract June 5 that will increase the district's recycled water system and free 4.4 million gallons of drinking water, enough to supply 425 households with their annual water needs. The district provides drinking water and sewer service to Dublin and the Dougherty Valley and sewer service to Pleasanton and parts of San Ramon.

Construction to increase the purple pipe system that delivers the recycled water is expected to begin in the next few months and the bulk of the work should be complete by the time school begins in August, said David Requa, the district's assistant general manager.

Dublin High School and Frederiksen and Murray Elementary schools and Cronin Park are the four school district properties that will receive the recycled water as well as three city parks -- Kolb, Stagecoach and Alamo Creek.

"We are well aware of the situation with the Delta and the potential limitations on water," Requa said. "This helps because any gallon of (drinking) water that we replace will help alleviate that concern."

The district has 56 miles of recycled water pipes that serve 60 customers at 224 locations in Dublin and San Ramon. The agency first began using recycled water in 1990 to landscape irrigation along Interstate 580 near its water plant. Recycled water returned to the district in 1999 at the Dublin Sports Ground.

Zone 7, which sells water to the district as well as Pleasanton and Livermore, receives just more than 80 percent of its water supply from the Delta, said Kurt Arends, Zone 7's assistant general manager.

"The long-term reliability of water has been declining, and we need to find other ways of getting water," Arends said. "Year to year, we are able to ride out droughts and store water during the wet season, but it is the long-term element that we need to focus on."

The use of recycled water will help lessen the demand on the Delta and help restore that long-term health, Arends said.

Dublin San Ramon Services District and the city of Livermore are the two water retailers along the 580 corridor in the Tri-Valley that have a recycled water system.

Livermore began using recycled water back in the 1970s at the airport and has expanded the use on the west side of the city near the Isabel expressway. The city has 15 miles of recycled water pipes and will add the feature to the Paragon Outlets, said Randy Werner, Livermore's water supervisor.

Dublin San Ramon Services District was awarded a $1.3 million state grant back in August to help pay for the construction. The district is also exploring the possibility of expanding the system to Camp Parks, the army reservist base, to Santa Rita Jail and to the Federal Correctional Institution and areas west of Interstate 680.

Contact Robert Jordan at 925-847-2184. Follow him at Twitter.com/robjordan127.