The Dublin San Ramon Services District (DSRSD) discovered bacteria in several Dublin water samples taken around town last week, though after flushing and re-testing officials found the water to be clean and safe to drink the next day.
The announcement came days before the district acknowledged that a sewer rehabilitation project was causing a plastic smell in the central Dublin air this week.
Tests by DSRSD lab chemists on Aug. 2 found that three drinking water samples taken the previous day tested positive for total coliform and E. coli.
Water operators flushed systems at the locations in question -- on Scarlett Court, Asterwood Drive and Central Parkway. They then re-sampled at the original sites, also taking five samples upstream and five downstream, and all samples were found to be clean Aug. 4, DSRSD officials said.
"This is not a consistent problem, and the drinking water is clean and safe to drink," said operations manager Jeff Carson.
Coliform bacteria are not likely to cause illness themselves, but their presence can be an indicator that disease-causing organisms -- also known as pathogens -- are in the water system, DSRSD said. E. coli is found in fecal coliform, and indicates that water systems may have fecal pollution.
In all three Dublin locations, chlorine residual -- a measure that ensures that there's enough chlorine to keep water clean and safe -- was low, but after flushing, levels returned to normal, officials said.
District water operators collect weekly water samples every Tuesday.
In more DSRSD news, the district is rehabilitating a major sewer pipeline that stretches from Village Parkway in Dublin to the wastewater treatment plant in Pleasanton.
On Tuesday, officials warned residents and businesses in central Dublin that they may notice a plastic smell that same day and on Thursday, coming from styrene resin in the pipe liner the district is installing in the sewer main. The work would last for four or five hours each afternoon, and officials recommended that nearby residents and businesses keep their windows closed during that time.
While the odor is palpable even at a low concentration, it's not hazardous, according to DSRSD officials.
The pipeline project is expected to last through this month in Dublin and then from later this month through October in Pleasanton. In residential areas, work will be done in daytime to avoid disruptive noises at night, while in commercial areas, the contractor will work around the clock to expedite the process.
DSRSD provides water service to Dublin and the Dougherty Valley area of San Ramon, wastewater service to Dublin, south San Ramon and Pleasanton (by contract), and recycled water for those communities.