The cost would rise again, by smaller amounts, in 2015 and 2018, according to a press release from Cal Water issued July 12.
The utility provides water to 18,800 addresses in Menlo Park, Atherton, Portola Valley and Woodside. The Menlo Park Municipal Water Department, operated by the city, serves Sharon Heights and portions of town east of El Camino Real.
Cal Water said the 15.2 percent hike was needed to cover rising operational and maintenance expenses in the face of decreasing water sales revenue.
"Unfortunately, water costs are rising, not just here, but throughout the country. Many of them — such as costs for materials, water production, and water treatment — are increasing faster than the rate of inflation," said Cal Water Bear Gulch District Manager Tony Carrasco in a written statement.
"Also, water use is going down, and water utilities have a lot of fixed costs that stay the same regardless of how much water customers use. That results in higher per-unit water costs. The good news is, some variable costs decrease when customers use less water, and those cost decreases are factored in. And conservation can save customers money in the long-term by enabling us to avoid having to invest in new sources of supply to meet higher demand."
According to Cal Water, it also wants to upgrade the water system infrastructure with six miles of new water mains, two pump station reconstructions, an emergency generator, and other features.
The California Public Utilities Commission will review the request during the next 18 months. Cal Water last asked for an increase in 2009; that 12.4 percent hike took effect two years later. The utility company won't necessarily get what it asked for — the 2009 increase was originally pitched at 17.4 percent.