Meeting Date:

January 24, 2017





David J. Stoldt,


Water Conservation


General Manager

Line Item No.:     



Prepared By:

Stephanie Locke

Cost Estimate:



General Counsel Review:  N/A

CEQA Compliance:  N/A


Supply Pressure

Water Wasted

Water Flow (Gallons)

50 PSI


65 PSI



80 PSI



100 PSI



150 PSI



SUMMARY:  High water pressure in a home is analogous to high blood pressure.  Appliances and water-using devices are designed to optimally work at certain pressures.  Pressure above optimal increases the likelihood of leaks and breaks in the water lines and appliances due to excessive force on the plumbing.  Water conservation devices such as toilets, showerheads, clothes washers, dishwashers, and faucet aerators use more water than they are designed to use when pressure is high (see graphic).  High pressure is often the cause of leaks in these appliances/devices and in water heaters and softeners, ice machines, irrigation systems, etc. 


Building codes require water pressure regulating devices or valves (PRVs) when the pressure exceeds 80 psi.  A PRV is a bell shaped device often located on the main line inlet pipe and usually near the house shut off valve outside the home.  Generally speaking, recommended water pressure in a home is 50-60 pounds per square inch (psi); the maximum safe allowable pressure is 80 psi.  California Plumbing Code, section 608.2 states; “Excessive Water Pressure. Where static water pressure in the water supply piping is exceeding 80 psi (552 kPa), an approved-type pressure regulator preceded by an adequate strainer shall be installed and the static pressure reduced to 80 psi (552 k Pa) or less.” 


PRVs control both the water pressure and the flow rate of the incoming water supply. A damaged or worn out pressure regulator can result in destructively high water pressure in the building.  Private pressure reducing valves have a lifetime of approximately ten years.  Most customers know little about the device’s function or that it must be periodically checked to be sure it is operational.  In our area, failed PRVs are prevalent.  Homeowners and commercial property owners are often not knowledgeable about their PRVs, not realizing that they have these devices and that they fail over time.  In other cases, there is no PRV and the incoming water pressure far exceeds optimum pressure.




In the 2013 Cal-Am General Rate Case, MPWMD was approved for a pilot Pressure Reducing Valve Program.  District staff is interested in reducing consumption and expanding the lifetime of water efficient appliances by ensuring that water pressure is maintained at an optimum level. To achieve this goal, staff has been obtaining pressure readings and considering a program to reduce pressure on the customer’s side of the meter.  Staff has been collaborating with Mike Rachel of Peninsula Home Inspections LLC, who has collected pressure data for more than 200 homes in the California American Water system between 2012 and 2016.  His testing identified a high percentage of homes that had water pressure levels that exceeded 60 pounds per square inch (“psi”), and he has also found a high incidence of non-functioning pressure reducing valves. 


For example, in 2015, MPWMD staff and Mr. Rachel conducted pressure testing at homes in an area of Monterey (Alta Mesa Circle) and determined that pressure in that residential neighborhood exceeded 145 psi: Approximately half of the homes tested had failed pressure reducing valves.  In one case, the homeowner said her freezer’s ice maker broke due to high water pressure.  In another, an Irrigation System was not functioning properly, with emitters popping off as the result of the high pressure and no pressure reducer on the Irrigation System. 


Staff has been testing water pressure as part of the inspection process and has collected more than 200 readings to date.  The information is being mapped to identify areas with pressure between 80-100 psi (as one data point) and above 100 psi (as another data point).  Staff proposes to target these high pressure areas for a pilot program whereby the District would provide PRVs for installation by licensed plumbers.  The participant’s water use will be tracked to determine savings and the success of the program.  




This proposed PRV program consists of three parts:


First, the District will undertake an effort to educate people about high water pressure.  This will be done through direct mail and local advertising.  A brochure will be distributed to local plumbing supply businesses and to our local civic centers.  Information will be provided on our websites and social media, and a short ad may be played in the local theaters.  Pressure testing will be done on request, giving staff an opportunity to inform the homeowner or business about the pilot program.


Second, Cal-Am customers with excessively high water pressure will be targeted to install functioning PRVs.  The concept is to contract with qualified licensed plumbers who agree to install or replace PRVs at a set price or price range.  The District will stock quality PRVs that will be available for installation by the licensed plumbers during the pilot phase of the program.  The District will pay for installation in exchange for access to consumption information.  Participants will also be given a pressure tester so they can periodically test their pressure.  The participant’s water use will be tracked over a two year period to determine savings and to obtain feedback. 


Third, MPWMD will encourage and support efforts by Cal-Am to reduce system pressure in areas where pressure nears or exceeds CPUC General Order 103-A (Rules Governing Water Service, Including Minimum Standards for Operation, Maintenance, Design and Construction).  Section VII-6, Pressures, states:


A.    Variations in Pressure

Each potable water distribution system shall be operated in a manner to assure that the minimum operating pressure at each service connection throughout the distribution system is not less than 40 psi nor more than 125 psi, except that during periods new PHD [Peak Hour Demand] the pressure may not be less than 30 psi and that during periods of hourly minimum demand the pressure may be not more than 150 psi. Subject to the minimum pressure requirements of 40 psi, variations in pressures under normal operation shall not exceed 50% of the average operating pressure.


RECOMMENDATION:  The Committee should discuss the concept program and provide direction to staff.