Backflow Testing in Aspen Hill, MD That Keeps Your Assemblies Working and Your Records Current

Backflow happens in two ways. Backsiphonage occurs when pressure in the supply main drops, perhaps during a water main break or heavy firefighting demand, and water inside a building is pulled backward toward the street. Backpressure occurs when a system inside the building, such as a boiler, a pump or an elevated tank, pushes water at a higher pressure than the supply. Either condition can carry contaminated water into the drinking water system if a cross-connection exists.

Cross-connections are common. Lawn irrigation systems sit in soil treated with fertilizers and pesticides. Hydronic heating systems often contain treatment chemicals. Fire sprinkler lines hold stagnant water for years. Commercial kitchens, car washes, laboratories and medical offices have their own hazards. Plumbing codes and water providers require an appropriate backflow assembly wherever these connections exist.

Different assemblies protect against different levels of hazard. A reduced pressure principle assembly uses two independent check valves with a relief valve between them that discharges water if the checks fail, making it suitable for high hazard connections. A double check valve assembly uses two checks without a relief valve and is used for lower hazard situations. Pressure vacuum breakers and spill-resistant vacuum breakers protect against backsiphonage on irrigation systems and similar uses.

Because these assemblies rely on springs, rubber seats and moving parts, they can fail without any visible sign. That is why water providers typically require testing when an assembly is installed, after it is repaired or relocated, and at regular intervals, often yearly. Testing must be performed by a tester holding the certification recognized by the local water provider, using a calibrated differential pressure gauge.

During the test, the technician briefly shuts the water off downstream, connects the test kit to the assembly's test cocks and measures how each check valve and relief valve performs against the standard criteria for that device type. The results are recorded and, where the water provider requires it, submitted on the provider's form or portal.

If an assembly fails, it does not always need replacement. Many failures come from debris lodged on a check seat, a worn rubber disc or a weakened spring. Rebuild kits restore those parts, and the assembly is retested afterward. When the body is cracked, parts are unavailable or the assembly is the wrong type for the hazard, replacement is discussed.