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What is RPZ Backflow Prevention?

rpz backflow

What is Backflow?

Backflow prevention is probably something you’ve given very little thought. Most of the time when consumers think about plumbing, it’s for installation, repair or unclogging drains and toilets. Maybe when you think of plumbing you imagine the dreaded frozen pipes. Plumbers have a lot of responsibilities to keep your home running properly. Plumbers are also responsible for taking care of any problems with backflow.

Backflow preventers ensure that water in a home or business boiler system does not flow into the drinking water. The water in your pipes is only to flow from the city’s water source to the point of use. If it flows backward from your home or commercial facility, then it is backflow.

What is Backflow Prevention?

Backflow prevention is absolutely necessary to keep the dirty boiler water from going back into the home drinking system. One type of backflow prevention system is called a pressure vacuum breaker. In homes, the pressure vacuum breaker would be installed at least 12 inches higher than the highest sprinkler on an outdoor irrigation system.

What is an RPZ Backflow Prevention System?

An RPZ is a newer system of backflow prevention. RPZ stands for Reduced Pressure Zone. Regulations no longer require RPZ’s to be rebuilt every four years. In a home, the most common place a backflow preventer is used is with the sprinkler irrigation system. The other common area it may be found in a home is with the water supply piping to a steam or hot water heating system. In a home with alternative heating or a forced-air furnace, RPZ’s are used as a secondary safety system. Minnesota code deems the pressure coming into the house in these situations to be adequate to prevent backflow.

Backflow prevention in a commercial setting is mandatory because of the large amount of water usage and the amount of mechanical equipment needed. Residential buildings with more than three families living there are treated the same way as commercial buildings. Annual testing on commercial systems has been required for a number of years.

Testing Code

A change in the Minnesota testing code was enacted on January 23, 2016. It requires the annual testing of backflow prevention systems. This is a change that affects new installations of sprinkler systems at a home. Here is the code language for this new law.

603.4.2 Testing. The premise owner or responsible person shall have the backflow prevention assembly tested by a certified backflow assembly tester at the time of installation, repair, or relocation and not less than on an annual schedule thereafter, or more often where required by the Authority Having Jurisdiction. The periodic testing shall be performed in accordance with the procedures referenced in Table 1401.1 by a tester qualified in accordance with those standards.

Complete details for what included in the code for backflow prevention can be found by reviewing the Minnesota Codebook.

The devices are to be tested once a year by a certified tester. If your device would be found not working properly, it will need to be repaired or replaced.

As a homeowner, if you get a new sprinkler system installed in your yard, you are required to have a backflow prevention system on it. The new system with backflow prevention is what is covered in the testing code and needs to be tested every year. Unless you replace the backflow prevention system, you do not have to have old systems tested. The requirements are only for going forward with new systems. The water department for your municipality will send out reminders of when you are due to get your system tested. This reminder system may vary from municipality to municipality but generally consists of notice 30 days ahead, a notice at the due date, a notice 30 and 60 days after the due date. Your water can be shut off for failure to comply with the requirement.

Certified Testers

The testing must be done by certified testers. It is not a DIY job. Certified testers might be a plumber, but not all plumbers are certified testers. The certification is done by being licensed by the Minnesota Department of Labor and Industry.

Individuals performing or offering to perform the installation, maintenance, testing, repair, replacement or rebuilding of backflow prevention assemblies must be certified by our agency as either a backflow prevention rebuilder (BF) or backflow prevention tester (BT).

Backflow prevention rebuilder: an individual holding a current plumbing license who may install, maintain, test, repair, replace or rebuild reduced pressure zone backflow prevention assemblies having completed reduced pressure backflow prevention assembly training approved by DLI.

Backflow prevention tester: an individual may test reduced pressure zone backflow prevention assemblies provided the individual completed reduced pressure backflow prevention assembly training and obtained certification from DLI.

An individual does not have to be a licensed plumber to hold a backflow prevention tester certification. But, they must submit proof of an  ASSE 5110 certification. The certification is a specialized 40-hour training course that trains an individual in the rebuilding or testing of backflow systems. The certification is good for three years, and the holder must renew the certification by a refresher course, written exam and practical exam. There are over 19,000 ASSE 5110 certified rebuilders and testers throughout the nation and Canada.

Everyone wants to keep their water system clean, safe and uncontaminated. It can seem like it is “just one more thing required”, but who would be comfortable knowing they are contaminating the public water system.

At Metro Heating and Cooling, we take your needs seriously. If you are going to have a sprinkler irrigation system installed this year, or if you need testing, rebuilding or replacement of your present RPZ backflow prevention system we have the certified employees to assure you are meeting the requirements to keep your water system in the Twin City area safe.   Contacting us is easy to do, and we will schedule a time to service you.

Schedule a HVAC repair anywhere in the Minneapolis or St. Paul area today by calling (651) 294-7798 or by requesting an estimate online.


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1220 Cope Avenue East, Maplewood, MN 55109