You shouldn’t be expected to know every single valve in your plumbing system — that’s what we’re here for! We can tell you everything you should know about double check valves and their importance to your plumbing system as a whole. Earl’s Plumbing is here to help with all of your plumbing needs. Our team is here to serve, and all you have to do is call!
The Double Check Valve, or DCV, is a back flow prevention device designed to protect the potable (drinkable) water supply from contamination. In other words, it is a water quality safety device that prevents possibly contaminated water from backing into and/or entering your mainline and drinkable water.
In a residential capacity, this is the complicated-looking device that is buried in a fairly large valve box and is usually located near the water meter. The DCV is installed on the line that feeds the irrigation system. The irrigation system has many open points in the form of irrigation heads and slow drip emitter lines.
In most cases, these are below ground and could be susceptible to various contaminants entering through these open points. Contaminants such as insecticides, fertilizer, feces, etc. could enter the irrigation system and then eventually back into the main drinking water. This could obviously make you very sick, so the double check valve is an important safety device. It’s important to make sure your double check valves are not aged and are working properly, for your safety.
The DCV operates by a series of spring-loaded check valves that allows water to pass through one way but not the other way or backward, thus the “back-flow prevention.” This is a safety device in many ways like a properly working vacuum breaker on a hose spigot.
The DCV also has two pretty important shutoff valves that must be functioning. By “functioning” we mean that the handles have to be present, easily accessible, clear of mud and dirt, and not frozen in position with rust buildup. This is a very common issue because this valve is very rarely used and becomes “out of sight, out of mind” for many homeowners. A properly functioning DCV allows for proper safety testing, and water leak testing and it allows the irrigation system to turn off. For those of you that have had an irrigation valve malfunction or get stuck in the open position, you know how important these two handles are.
Most homeowners do not know what a properly installed DCV looks like because builders and irrigators rarely install them correctly. In fact, they usually use low-quality products that fail in time.
Here is what it SHOULD look like: when you open the lid of the valve box, the DCV should be completely exposed and clear of any dirt, mud, or debris. The valve box should not have ANY dirt or mud accumulation inside at all. You should be able to see the black plastic on all 4 sides all the way to the bottom of the box. And although it is not required by code like it is for PRVs, we always pack the bottom of our valve boxes with 3-6 inches of pea gravel. This allows for better drainage and keeps mud build-up down to a minimum for a longer period of time. So, yes all of our trucks carry 60 to 80 pounds of pea gravel because technically it is a plumbing item. And of course, we have both of the common sizes of double check valves on every truck.
There is no set timetable or expected life for a double check valve. Some sites say 5 years, but it is probably closer to 10 or even 15 years. But it also greatly depends on the environment and conditions in which it is located. If yours is completely buried in mud and clay and/or stays flooded and wet and exposed to soil minerals, then yes it might be 5 years. There is also a certain amount of scale build-up from our municipal water supply that takes a toll, but if properly installed, there’s no reason that a DCV should last 10+ if not 15 years.
From a residential standpoint, some cities require double check valves and other types of back flow devices be tested and certified every few years. An example, Lubbock requires residential DCVs to be inspected, tested, and certified every 3 years. As of now (May 2022), none of the cities that we operate in – Frisco, McKinney, Plano, Allen, Little Elm or Prosper – have any post-installation testing or inspection requirements for residential DCVs. We are hearing that could change in the future.
From a commercial standpoint, all businesses are required to have their double check valves and other back flow devices tested and inspected ANNUALLY. That should underline the importance of the functionality of these devices from a safety standpoint.
For the most part, there are 4 types of water leaks that are common in the yard. Three of those are the responsibility of the licensed plumber and 1 is for the licensed irrigator or homeowner depending upon the complexity. Those yard leaks are listed below in order of commonality based on our experiences:
When we get this call, the homeowner usually cannot tell us where the leak is. The call is usually something like, “I’ve got a leak near the meter and it’s rolling over the curb.” This type of leak usually requires excavation, but we have a few tricks up our sleeves that we like to try before we resort to that.
When the leak is not visually obvious coming from the meter nipple or one of the DCV connections, we are typically going to start at what we call the irrigation tee. We call it this because it is where the irrigators cut into your main water line and “tee off” to supply the irrigation system. Because irrigators are not plumbers and do not have the tools, torches, equipment, or the variety of quality parts that we have access to, this is where we typically find the leak. To “properly” make this repair and remove the inferior irrigation parts (PVC fitting and pipe) we often have to excavate and expose all the way to the double check valve. Since we have to make a new connection at the DCV, we often give the homeowner the option to replace the DCV at the time. If it is not in good condition because of age, then we do not give an option, we just make the replacement so that we can warranty the entire repair.
This is the next most common yard leak but it usually appears close to the home and/or in the flowerbed area. You are a candidate for this type of leak for similar reasons to a bad DCV in that the devices are buried in mud and clay or just aged. For more information, please see our PRV information.
This one belongs to the irrigation companies. It is possible that we could make this repair because it is not usually overly complicated. But we do not have the irrigation parts such as irrigation valves, sprinkler heads, drip irrigation lines, control wire, etc.
This type of replacement should be a last resort in most cases, but sometimes it is the best or most appropriate option. We have seen some crazy yard line leak situations, but most of the issues involve the materials used or the age of construction or a combination of the two. Simply stated there were materials used that seemed to be the best option(s) and approved at the time (Qwest, Poly, PVC, etc.) that just did not stand the test of time. Sometimes these leaks are significant but impossible to locate due to depth, location, size or some other variation. For more information, please see yard line leaks.
Double check valves are an important safety feature in your home that many homeowners don’t even know about. If there is a leak or you need a replacement, our team can help you out. Even if you just need someone to double-check your double check valves, our team of trained plumbers can help with that too. Contact us today to get started.