Residential Backflow Preventer - What You Need to Know

By | November 10, 2016

Like large commercial establishments, residential buildings are also vulnerable to the risks of backflow. Both are exposed to threats of sewage overflow and/or water contamination. Residential backflow preventer, on the other hand, adhere to different standards compared to their industrial counterparts. For example, establishments like hospitals and slaughterhouses that often process hazardous wastes and liquids require heavier-duty backflow prevention devices than typical residential buildings.

As per most plumbing codes, the following are the types of water system protection that are required in residential buildings:

  1. Backflow preventers or vacuum breakers on lawn sprinklers
  2. Vacuum breakers on sill cocks and hose bibs
  3. Anti-siphon type ball cocks in water closets
  4. Backflow preventers on supply lines to boilers or other equipment containing non-potable fluids and cross-connected to the potable water system
  5. Air gaps built into sink, tub and faucets

As far as residential backflow preventer are concerned, there are two main types of backflow prevention devices that are typically used in residential irrigation. One type is the Pressure Vacuum Breaker.  A Pressure Vacuum Breaker is the most common, inexpensive type of residential irrigation backflow preventer. It consists of an inlet shut-off valve at the bottom, a single valve body composed of a pressure vacuum breaker, check valve, and two test cocks, and an outlet shutoff valve.

Another one is the Reduced Pressure Zone Assembly. RPZ’s are commonly used when there are elevation changes in the lawn. They are also known to be most complex and expensive among the available backflow preventers for residential buildings.A reduced pressure zone assembly consists of an inlet shutoff valve, two independently operating spring-loaded check valves separated by a pressure differential relief valve, four test cocks, and an outlet shutoff valve.

Lawn irrigation systems need these residential backflow preventer to stop polluted liquids from contaminating your drinking water. Accordingly, building and plumbing codes require these irrigation systems be installed with such devices. Almost, if not all, cities require the installation of at least one kind of the above mentioned devices in a residence.

Overflown sewage can cause a lot of trouble for any building owner, not to mention the stink factor that comes with it. In terms of sewer management, there are various kinds of devices that would help avoid the incidence of overflowing sewage.

Generally, residential sewer backflow preventer are categorized under the umbrella term “backflow prevention device”. However, one should not confuse the term backflow preventer with backwater valves. Backwater valves prevent raw sewage from backing up into your home through the toilets, showers and other parts of the house.  Unlike residential backflow preventer, backwater valves do not deal with protecting potable water sources from being contaminated by reverse flow of polluted water. Instead, they deal with preventing overloaded sewer line from backing up into your basement.

While there are a lot of differences between residential backflow preventer and backwater valves in general, these two devices both help in maintaining the natural flow of liquids inside your pipeline. Both devices save the building owner from any unwanted incidence of overflow or water contamination.