Water Pressure in the Phoenix Area

What is high water pressure?  What is low water pressure?  What does water pressure affect in your home?  Let’s get down to the fun of it, things to know about water pressure in your Phoenix Metropolitan area home and things that can be done to increase your water pressure and lower your water pressure. 

High water pressure isn’t just an opinion, it is measurable and has serious consequences for the plumbing in your home.  High water pressure is any pressure in your home that is over 80 PSI (Pounds Per Square Inch)  Homes newly built are required by UPC (Uniform Plumbing Code) to have a pressure regulating valve installed if the pressure to the home is 85 PSI or higher.  

The UPC Code reads “608.2 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 kPa) or less. Pressure regulator(s) equal to or exceeding 1-1/2 inches (40 mm) shall not require a strainer. Such regulator(s) shall control the pressure to water outlets in the building unless otherwise approved by the Authority Having Jurisdiction. Each such regulator and strainer shall be easily located aboveground or in a vault equipped with a properly sized and sloped bore sighted drain to daylight, shall be protected from freezing, and shall have the strainer readily accessible for cleaning without removing the regulator or strainer body or disconnecting the supply piping. Pipe size determinations shall be based on 80 percent of the reduced pressure where using Table 610.4. An approved expansion tank shall be installed in the cold water distribution piping downstream of each such regulator to prevent excessive pressure from developing due to thermal expansion and to maintain the pressure setting of the regulator. Expansion tanks used in potable water systems intended to supply drinking water shall be in accordance to NSF 61. The expansion tank shall be properly sized and installed in accordance with the manufacturer’s installation instructions and listing. Systems designed by registered design professionals shall be permitted to use approved pressure relief valves in lieu of expansion tanks provided such relief valves have a maximum pressure relief setting of 100 psi (689 kPa) or less.”

Reading the Code Book is so fun, it has always fascinated me that the code is written in attorney language but meant to be read and implemented by skilled tradesmen who would rather go burn themselves soldering something and making it beautiful than to read a book, especially one written by attorneys. 

What is Low Water Pressure in Phoenix? 

Low water pressure can be incredibly irritating when you’re trying to rinse the soap out of your hair but opinion and frustration aside, low water pressure according the UPC of 2018 defines low water pressure as any pressure below 15 PSI.  Hey, look at some more fun reading in the code book “ 608.1 Inadequate Water Pressure. Where the water pressure in the main or other source of supply will not provide a residual water pressure of not less than 15 pounds force per square inch (psi) (103 kPa), after allowing for friction and other pressure losses, a tank and a pump or other means that will provide said 15 psi (103 kPa) pressure shall be installed. Where fixtures, fixture fittings, or both are installed that require residual pressure exceeding 15 psi (103 kPa), that minimum residual pressure shall be provided.” 

As I’ve referenced in other blogs, each state and each city’s jurisdiction can hold a higher standard than the UPC, thank goodness in this case, the ADEQ requires a minimum of 20 PSI, AZDEQ’s website says this about water pressure “What is ADEQ’s regulatory authority for water pressure? ADEQ enforces Arizona Administrative Code Title 14 Chapter 2 Article 4, which regulates for at least 20 pounds per square inch (psi) in drinking water distribution systems. Arizona Administrative Code Title 14 Chapter 2 | View > Why is it set at 20 psi? For drinking water distribution systems, 20 psi is a common minimum required water pressure to prevent potential infiltration of contaminants. Typical home water pressure can range from 30 to 60 psi. What has ADEQ done to address low water pressure reports by Johnson Utilities customers? ADEQ issued a Compliance Order for low water pressure in July 2018, with a fine of $10,000 after a pump failure cause widespread low water pressure issues in one neighborhood” 

What is realistic when it comes to low pressure in your home?  Each of us have a different opinion on low pressure but especially comes to light depending on the plumbing fixtures we are using.  For example if you’re installing a tankless water heater and the water in your home is at a lower PSI you’re going to notice a drop in water pressure on the hot side of your faucets and shower valves.  If you have pressure balancing shower valves and faucets (some single handle faucets and shower valves) then you’re going to notice a drop in pressure regardless of temperature because pressure balancing plumbing fixtures balance themselves to the lower pressure coming in.  For example if your cold side water pressure is at 60 PSI and now your hot side PSI is at 50 PSI because of the tankless water heater now your faucet will be at 50 PSI to balance out the pressure. 

What Will High Water Pressure do to my Plumbing? 

Many of the plumbing fixtures in your home work best under ideal conditions, like me ha ha ha which is usually with a nice glass of red wine, a keyboard and either some jazz or classic rock in the background, but that aside, in all seriousness your plumbing is affected by pressure.  

The ASME (American Society of Mechanical Engineers) are a governing body for plumbing materials and fixtures and they require manufacturers to build and spec their products to perform within PSI parameters.  Brands like Kohler, Moen, Toto, American Standard, Delta are held to a standard of PSI and tested under these specific requirements.  There are a lot of plumbing fixtures in the world, when you consider each brand, model, type of fixture, pipe, fittings, valves, heaters, tanks, pumps, etc there are hundreds of thousands of different plumbing items on the market, squirrel, I forgot toilets, shower valves, tankless heaters, the list goes on.  My point is when it comes to high pressure many of these items are tested and they can work under these conditions, but not how long they will.  

Kohler has a simple to read reference on their website that I think you will find helpful in explaining the ranges that a plumbing fixture will work best 

“Kohler fixtures must meet ASME codes regarding pounds per square inch (psi). Please review the product’s Specification Sheet for the Codes and Standards that your product meets. Some fixtures do require specific pressures and flow rates, as indicated on the product’s Specification Sheet.


General Minimum and Maximum Pressure Recommendations


Faucets:  ASME codes require supply fittings to function at a minimum of 20 psi to 125 psi maximum (this includes metering and self-closing faucets).
Toilet Fill Valves:  Kohler tests fill valves from 20 psi minimum to 80 psi maximum.
Gravity Toilet Tanks:  ASME/CSA codes require a minimum of 20 psi to a maximum of 80 psi static.
Electro-Hydraulic Toilets (Power Lite):  ASME/CSA codes require a minimum of 20 psi to a maximum of 80 psi static.
Pressure Assist:  1.4 gpf requires a minimum of 20 psi and a maximum of 80 psi.  1.1 gpf or less requires a minimum of 35 psi to a maximum of 80 psi static.
*Flushometers:  Siphonic flush bowl style requires 25 gpm at 35 psi minimum and 80 psi maximum static. Blow out flush bowl style requires 25 gpm at 45 psi and 80 psi maximum static.

 *Flushometers are more complex as the National consensus standard (shown above) is not the same as plumbing model codes.  Model codes typically call the minimum static pressure minimum running pressure. The pressure drops seen across various manufacturers’ valves is also not consistent and depends on the design of the water supply system in the building.  In addition, a product may be specifically designed to require different pressures and flow rates; this would be indicated in the specification sheets.”

It has been our experience that plumbing fixtures and pipes left under high pressure over extended periods of time can reduce their lifespan dramatically compared to homes with normal PSI.  Common side effects of high water pressure can be leaking shower valves, leaking faucets, leaking pipes, reduced life span of plumbing appliances like dishwashers and even water heaters.  I always try to explain that high water pressure in your home is a lot like high blood pressure in your body, everything has to work harder than normal so the lifespan can be reduced.  

A product that we install called Stream Labs has a setting that can detect and alert you about water pressure, but aside from that I found this page on their website informative and a great resource for water pressure, they even explain water pressure as an analogy like I do.  I find that lessons explained in relatable terms just click better for me. 

If you get pressure alerts or notifications when you run water, there may be an issue with your municipal water supply, or with your pressure-regulating valve (PRV). For example, if your pressure is too high (whether water is flowing or not), it is possible that your PRV is no longer functioning properly and needs to be replaced.  Depending on the age of your home, it is also possible that there is not a PRV installed; check with your plumber.  Just like blood pressure for people, high water pressure is a serious risk to the health of your home plumbing system.  Many appliances are only rated to handle incoming water pressure up to 80 psi.  Constant pressure above that level can cause supply lines to appliances to fail prematurely and burst.

Too High:

  • 70 psi – Just above Normal Pressure Reducing Valve Settings
  • 80 psi – Prolonged pressure above these levels may damage appliances. (Recommended)
  • 90 psi – Max rating for most whole-home filtration systems.
  • 100 psi – Max rating for most appliances

The bottom line, high pressure over extended periods of time can cause flooding, leaking faucets, running toilets, leaking shower valves and can reduce the lifespan of appliances and plumbing fixtures and should be addressed by a local licensed plumbing company that you trust like the team at Robins Plumbing. 

Here is a quick myth busted

“I can just reduce my water pressure by closing my main water valve or angle stops a little”

This is absolutely NOT the case. It might appear to reduce the pressure but what is actually happening is you are reducing the volume of water making through the valve. So when you turn on the faucet the amount of water coming through drops. As soon as you turn that faucet back off then the pressure builds right back up to match the city water pressure being provided. So you’re just torturing yourself with a lack of water and still negatively affecting your fixtures and appliances. To make matters even worse, closing that valve or angle stop a little can create the dreaded water hammer. A water hammer can make a very annoying knocking or screaming sound throughout your entire house and is very bad on your fixtures and appliances.

What Will Low Pressure do to My Plumbing? 

Low pressure isn’t as urgent of a concern as high pressure, it is honestly more of a nuisance and affects lifestyle, and my happiness.  Low water pressure affects the volume of water coming from your plumbing fixtures and can have you yelling at someone in your home for turning on a faucet while you’re trying to shower because now you feel like you’re trying to bathe in a stream of water.  You’ll get especially frustrated when you use water at your friends house and their running at the ideal 65-75 PSI and you’re running at 20….don’t hate them, it isn’t their fault and there is a solution.


How to fix High Water Pressure In Phoenix

Fortunately if you have high water pressure there is a solution, our epic team can install a PRV (pressure-regulating valve) on your home allowing you control over the incoming high water pressure to your home.  PRV’s are devices that are installed on the incoming water for your home that work by using springs against a diaphragm to control the pressure of the incoming water.  To put it simply as possible the diaphragm has pressure applied to it from behind by a spring that is adjustable using a bolt that is tightened or loosened to adjust the pressure. When the incoming water hits the diaphragm it has to push on it to get through thus lowering the pressure that actually gets through the PRV. It is not uncommon to have to check your pressure and adjust it from time to time as the diaphragm loses its elasticity, and eventually you will have to rebuild or replace your PRV. 

How to fix low water pressure

If you have low water pressure then unfortunately it is going to be a little more complicated and cost a bit more to fix, however it is very doable. In order to increase your pressure it is going to require a booster pump, and in some applications or systems an pressurized holding tank as well. But let’s keep to the simpler system for now. A booster pump pretty much does exactly as it sounds. It boosts the water pressure. The size and power of the pump will vary depending on your particular plumbing system and pressure needs or wants. Modern pumps such as the ones made by Grundfos or little giant are compact, long lasting, adjustable, and in most cases can be powered by your standard electrical outlet. If your pressure is really bad then more powerful models are available. You can even get larger booster pumps for commercial applications.

If you have low water pressure to just your faucets and not your entire home, you may not need a booster or anything fancy, you might need a simple fix which you can read all about on our blog and video  Fix Low Water Pressure at Your Faucets.


The bottom line

It’s a good idea to know what your incoming water pressure is. Very often you will find that your pressure is just fine and the implementation of pressure devices is not needed, however whether you have high or low pressure there is a way to fix it and we recommend you do so. 

If you’re interested in getting control of your water pressure than give Robins Plumbing a call at 623-486-4657 or we can be reached online at Robinsplumbing.com and info@robinsplumbing.com

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