Holliston’s mandatory odd/even water restriction is back in effect, after a July 11 electrical problem at the Dopping Brook treatment plant prompted a five-day total ban on outdoor watering while it was fixed. The annual summertime limits on outdoor water use are based on state conservation requirements. From May 1 through Sept. 30, residents with properties with even street numbers may water lawns on Tuesdays and Thursdays before 9 a.m. and after 5 p.m., while outdoor watering of lawns for properties with odd street numbers may take place outside the restricted hours on Wednesdays and Fridays. Nonessential water uses, including irrigation of lawns, and washing vehicles, outside building surfaces, driveways, or sidewalks, is prohibited. In addition, no lawn watering is allowed on Saturdays, Sundays, or Mondays. Questions about the mandatory water limits can be directed to the Water Department at 508-429-0603. Full story for BostonGlobe.com subscribers.