reduced pressure zone valve

Signs Your RPZ Valve is Going Bad

Plumbing problems are bad, but they become even worse when they pose a danger to your health and the health of people in your apartment, school, or business. The reduced pressure zone (RPZ) valves in your plumbing systems stand between you and illnesses caused by contaminated water. If these valves aren’t working properly, you’ll want to know right away so you can call your plumber and get an immediate repair. Here are the details on what an RPZ valve is, signs that your RPZ valves need attention, and what you can do to prevent future issues with your RPZ valves. 

What Is a Reduced Pressure Zone Valve?

Plumbing by Andy Rogers is licensed with CC BY-SA 2.0
Also known as a backflow preventer, an RPZ valve is a system on a water pipe installed to prevent back pressure and back siphonage from contaminating clean water. It's formed of two independent check valves and a relief valve between them. They're not usually necessary for single-family homes, but you'll find them in apartment buildings, businesses, and municipal water systems — anywhere the water demand is high. 

An RPZ valve keeps the dirty water or waste in your pipes from flowing backward and contaminating your clean water supply. RPZ stands for reduced pressure zone, which refers to the fact that RPZ valves use the force of reduced pressure to keep dirty water flowing in the same direction. Although it isn't the only kind of backflow preventer, an RPZ valve is a more secure device than a single or double-check valve, which are other kinds of backflow preventers. This is because The RPZ valve has an extra relief valve. 

When there's a sudden reduction in water pressure due to high water demand or a pipe failure elsewhere, the dirty water flowing out from sinks, drainage systems, and toilets can be sucked back into the water system and mixed with your clean water. Your RPZ valves use a differentiated pressure system to keep the backflow from entering potable water. In Illinois, RPZ valves are required to be installed in any building along with fire prevention systems, irrigation systems, or large boilers. If you have any of these things in your building, you have RPZ valves installed on your water pipes. 

Signs That Your Reduced Pressure Zone Valves Might Be Going Bad

Now that you know what an RPZ valve is, you'll want to learn how to tell if yours needs to be fixed or replaced so that you can prevent your clean water from becoming contaminated and keep the people in your building from illness. Here are some signs that your RPZ valves might be going bad: 

Bad Water

If your water is cloudy or discolored, smells or tastes bad, or has little particles swimming around in it, it's definitely time to call a plumber. When this happens, it usually means that one of your RPZ valves has failed completely and that a backflow has made it into your clean water supply. Bad water qualifies as an emergency, so you shouldn't delay the fix. If anyone has drunk the contaminated water, you should watch them for signs of dysentery, salmonella, and other waterborne illnesses. 


A whole host of things cause plumbing leakage, from rust to thermal expansion to changes in water pressure. An RPZ valve will not always leak when it needs repair, but a leak is still the most common sign of a problem with the valve. If you see water flowing out of the relief valve, this may mean that the two check valves have failed, which indicates that it's time to replace the whole RPZ system on that pipe. It could also suggest that there's debris caught in one of the check valves, which calls for a valve cleaning.

Slow Flow or Drainage

Slow water flow can have many causes other than a bad RPZ valve, like high water demand or a poor water supply system. However, if you're experiencing consistent bad flow or your water is taking forever to drain, it's time to get those RPZ valves looked into. The slow water may be due to a pressure buildup in the valve, which will delay your water supply. An experienced plumber will be able to fix this problem for you. 

How to Prevent Your Reduced Pressure Zone Valves From Going Bad

While the RPZ valve is a reliable device for preventing water contamination, it has a lot of parts that can go wrong or just fail from age or wear. However, you can do some things to anticipate or prevent these issues. 

Regular Plumbing System Maintenance

Maintenance is the most important thing you can do for your RPZ valves and your whole plumbing system. Regular plumbing checks will catch any developing issues in the valves before they fail and allow your water supply to be contaminated by backflow. Make sure to set up regular maintenance with your plumber. 

Regular Tests and Certification

This is usually a part of regular maintenance, but it deserves a special mention because of the annual testing that water companies are required to carry out on RPZ valves in Illinois. The law demands that RPZ valves be tested by a certified tester when they are first installed and at least once a year after installation and that up-to-date records of the tests are kept on the site. 

So, get a certified tester into your building or business every year to look at your RPZ valves and check off those certificates. Not only will this keep your building on the right side of the law, but it will also protect you and the other people in the building from contaminated water caused by a valve failure. 

Hopefully, this has helped you to understand the importance of your RPZ valves and how to tell if something is wrong with them. Prevent water contamination and illness by keeping an eye on your RPZ valves and getting them checked frequently. Don't forget to call Dahme Mechanical in Arlington Heights in case of emergencies or to set up regular maintenance.