Annual Water Quality Report The Mid-Peninsula Water District is pleased to present this 2011 Annual Water Quality Report (Consumer Confidence Report) to our customers. It is important to our Board of Directors and Staff that our customers are informed about the quality of your drinking water. The Mid-Peninsula Water District exists to serve our customers by obtaining and distributing a safe, reliable, high quality supply of water for current and future needs in the most cost efficient manner.
Hexavalent Chromium in the Hetch Hetchy Water System
All of SFPUC'S current surface water supplies, with the exception of Lower Crystal Springs and San Andreas, were non-detect for hexavalent chromium. Lower Crystal Springs and San Andreas had one sample each just above the detection level of 0.1 ug/L (0.2 and 0.1 ug/L, respectively). All detects are well below the 100 ug/L Maximum Contaminant Level (MCL) established by the U.S. EPA for total chromium and the 50 ug/L MCL established by the State of California for total chromium. Other Hexavalent Chromium Facts:
Water utilities are required to test for “total chromiumâ€, in which any presence of hexavalent chromium would be captured in the total chromium result.
MCL for total chromium in drinking water as set by the U.S Environmental Protection Agency is 100 ug/L (ppb). The California MCL for total chromium is even more stringent at 50 ug/L. MCLs are set best available analytical and treatment technologies and taking cost into consideration.
Chromium is a heavy metal that occurs throughout the environment naturally.
The U.S. EPA and California Department of Public Health are developing an MCL for hexavalent chromium.
Water Fluoridation Effective November 2005 A somewhat controversial subject with many of our customers has finally been decided for all of us by the San Francisco Public Utilities Commission. On February 16th, 2001, the San Francisco Public Utilities Commission adopted their staffs recommendation to construct new fluoridation facilities at the San Antonio Pump Station, referred to as the "East Bay Alternative." Engineering studies estimated that this new facility would cost less than upgrading the existing facilities at the Polhemus plant located on Polhemus Drive between Anza Blvd. and Crystal Springs Road. For the first time, this facility would provide fluoridated water to the 19 Bay Area water agencies that presently do not receive fluoridated water. This, of course, includes our Mid-Peninsula Water District. The new fluoride facilities has been completed and operational since November 2005.
New Disinfection as of February 2004 In February of 2004, our water supplier, San Francisco Public Utilities Comission (SFPUC), converted from chlorine to chloramine as their water disinfectant. Chloramine is the combination of chlorine and ammonia. The conversion to chloramine has allowed SFPUC and Mid-Peninsula Water District to increase protection of public health, while meeting stricter state and federal water quality regulations, lowering risk of bacterial contamination, and improving taste and odor.
Mixing System Installed In Storage Tanks
Because of the chloramine disinfection process that has gone into effect, early 2004, it is important more than ever for the water district to prevent the water from becoming stagnant for too long a period of time. In an effort to keep the water moving inside of our reservoirs, we have installed mixing systems and sampling stations in 7 of 10 storage tanks. These mixing systems will play a vital role in the effort to continue serving our customers the purest water possible.
