High Water Pressure
North San Diego County is an area with many variations of water pressure. Generally, water pressure is determined by one of two factors. The most common is when water is pumped from an original source, such as a lake or reservoir, or from underground and is arbitrarily set. Less common is when water is supplied by gravity from a source substantially above the area served.
When water is supplied from above, as it is in many areas of North County, high pressure develops as a half pound of pressure occurs for every foot of elevation that exists between source and demand. In other words, if a source is 200 feet above the point of use, 100psi of water pressure will be present below. In areas where water is pumped from below ground, it is common to have only 30-40psi available.
In some of the outermost ranges of North County, we have witnessed water pressure in excess of 300psi, on many occasions. Excessive pressure, it should be noted, if not corrected, will cause rapid wear on the various components of the plumbing system.
The Uniform Plumbing Code requires that systems that develop pressure in excess of 80psi, be protected by pressure reducing valves, commonly called “pressure regulators.” Excessive pressure is commonly the cause of premature wear causing leaky faucets, water closets and other valves, as well as water heater tank failure. It should be further noted that water heater warranties are void when pressure is found to be over the prescribed limit.
Even pressure of 60-75psi, is considered “high range” by the UPC, but falls under a “normal” rating. Pressure that rises above 150psi, commonly trips the temperature and pressure relief valve at the water heater, which is pre-set at 150psi, for tank protection and general safety.
A pressure gauge can be economically purchased and placed on a hose bibb, or washing machine valve to determine exactly what the pressure is on any given system. Pressure tends to surge at night when little water is being used in the area. Any reading over 75psi, confirms that the system is unprotected.