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You May Need Backflow Prevention Assistance in Your Home


Backflow prevention is a service that homeowners often don’t realize they need. When people think of “backflow preventers”—when they think about them at all—they think of the large assemblies sitting outside of commercial and industrial buildings. The purpose of these backflow preventers is civic: they stop the wastewater from the business from flowing the wrong direction through the plumbing, leading to bacterial contamination entering the public fresh water supply.

With homes, backflow prevention is a bit different. There are fewer places in a house where there are direct cross-connections between the wastewater and freshwater sides of the plumbing. For example, there’s a natural air gap in a sink between the drain and the faucet—the wastewater in the drain won’t leap up and go the wrong way down the faucet! But there are places in your home’s plumbing where you’ll need backflow prevention devices, and our certified plumbers can help you with ensuring your freshwater supply is protected from stale water getting into it.

Backflow and what causes it

First, we want to clarify on what backflow actually is. If there is a change in pressure in the plumbing system, with either an increase in pressure on the wastewater side or a decrease in pressure on the freshwater side, it will cause water to move the wrong direction through the plumbing. In a home, this can mean water from the common residential system—non-potable (i.e. non-drinkable) water—spreading into the fresh drinking water. There are a number of reasons for this change of pressure: the water main may be broken, firefighters may have placed a heavy demand on the local freshwater supply, a power outage has occurred, or there’s a new water-using appliance that alters the pressure.

Where backflow can be an issue in your home

Backflow can happen in any place where water can move backward and go into a freshwater pipe. For example, a hose showerhead can be lower than the water level in the shower. However, the appliances of the highest concern are boilers, radiators, and especially irrigation systems like sprinklers. To stop backflow at these locations, plumbers place special backflow valves. These valves will close in the event of water moving in the wrong direction, shutting off the movement of water.

If you’re unsure if your home needs backflow preventers or has them in already place, call on licensed and certified plumbers. Working with backflow prevention requires special certification, so not all professional plumbers can perform the work. In order to be a certified Backflow Tester in Maryland, a plumber must be at minimum a Journeyman Plumber and complete a State of Maryland-sanctioned 40-hour certification course for Cross-Connection Technicians. Afterward, the plumber must re-certify every three years.

We offer service for backflow prevention in Frederick, MD and the surrounding areas, and have certified Backflow Testers on staff. We can install prevention devices in places where you need them and take care of the occasional checks and replacements that will continue to protect your water supply.

Look to the Service Contractor of Choice for your backflow prevention services: Mallick Plumbing & Heating.