Full water service has returned to Castlewood with repairs completed in the well pump that failed and caused a serious water supply shortage Sunday in the neighborhood in southwestern Pleasanton, a San Francisco Public Utilities Commission spokesman said Monday morning.

Castlewood residents have been advised to boil all of their tap water before potable use for safety reasons until the city of Pleasanton can finish flushing the system on Monday.

"Our crews were able to repair the pump last night, and the repairs have held. Castlewood Reservoir was filled just past midnight early this morning," SFPUC press secretary Will Reisman told the Weekly on Monday morning.

"Full water service is available now," Reisman said. "SFPUC will continue to monitor the situation. A new pump has been on order, and should be installed early next month. A replacement for the second pump will soon follow in order to provide redundancy to the system."

Pamela Ott, deputy city manager for Pleasanton, said that the city is "now preparing the distribution system for water delivery to customers -- i.e., flushing the system -- and ensuring water quality. Until this is complete, Castlewood residents have been issued a boil water notice as announced on the attached handout provided to each residence."

The affluent Castlewood neighborhood and country club community off Foothill Road was left with a seriously depleted water supply on Sunday amid pump failures within the SFPUC-owned well system that serves that area in unincorporated Pleasanton.

Castlewood's water system, which is supplied solely by the SFPUC, is separate from and not connected to the city's potable water system. The city operates and maintains the Castlewood water and sewer systems under contract with the Alameda County Public Works Agency, Ott said.

On Sunday morning, SFPUC learned that one of its two groundwater well pumps for its Pleasanton well system had failed -- this after the other well was already inactive due to a pump failure one month ago and a replacement part on order, Reisman said. The SFPUC system is the sole water source for Castlewood residents.

As a result, SFPUC, city and Castlewood Property Owners Association urged Castlewood residents to limit their household water use to essential activities only Sunday as crews worked to temporarily supplement the water system's tanks while also trying to fix the underlying pump problem. The Club at Castlewood stopped irrigation for the day.

Stop-gap strategies on Sunday included trucking in water from SFPUC facilities in the Sunol Valley as well as trying to establish a hook-up connection to a nearby city fire hydrant to pull from the Pleasanton municipal water system.

Crews eventually determined the problem occurred due to the pump and electrical components overheating due to a failed fan inside the machinery, Reisman said. The SFPUC pump was repaired late Sunday night and the Castlewood lower reservoir was filled just after midnight Monday.