Backflow Preventers

Pressure Vacuum Breaker

Typically found on many residential irrigation systems.
Typically found on many residential irrigation systems.

What is a backflow?

An undesirable reversal of flow of a liquid, gas or solid into the potable water supply. A backflow preventer keeps this from happening. Allow me to give you a word illustration.

If you have drank a beverage through a straw you have created a vacuum by suction, the same thing happens when higher pressure fluids, gases, or suspended solids move to an area of lower pressure fluids. This is back-siphonage and an example of an indirect cross-connection.

Now imagine using that same beverage with straw and now you blow air through the straw and bubbles begin to erupt at the submerged end, you have now created back-pressure. If your breath had been, let us say natural gas, you would have forced that gas into a potable water tank and it in turn could be carried to your kitchen faucet. This is an example of a direct cross-connection.


Just one of many reported incidents!

Not picking on anyone, just let's get it fixed

In your home exists many possibilities for backflow to occur, We should always be aware of what we are putting the end of our hoses to, If you have an anti-siphon hose bib, it will have a circular disc shaped piece on top, someone was doing some forward thinking. But they don't last forever as they are susceptible to freeze damage and general wear and tear.

Another potential for cross-connection (backflow) to occur is on that same anti-siphon hose bib when you hook up a power washer to it, remember the key compound word here is (anti-siphon) the pressure in the pump on the power-washer can overcome the pressure coming from your hose-bib and then it can introduce cleaning chemicals into your homes water system. It would be smarter to have the contractor or you, fill an external tank to draw your water supply from, problem solved.

Just in this one example you can see how a common task could be having an adverse effect on your families well-being. These anti-siphon hose bibs only offer protection against back-siphonage and not back-pressure. If you have no device currently in place on your hose connections, my advice to you is to buy and install now.

Another place in the home for back-pressure and back-siphonage to occur with potentially harmful contaminants? The BOILER! Yup that old boiler is full of old water quality deprived, mineral and chemical infused liquid that looks like triple boiled coffee and you din't want any. For this type of water feed connection you will at a minimum need a dual check, and truly these should be replaced every five (5) years as they are not testable.



Reduced Pressure Zone Assembly

Suitable for irrigation and water to pier applications above the grade.Wilkins Co. RPZ model 975XL
Suitable for irrigation and water to pier applications above the grade.Wilkins Co. RPZ model 975XL

My handywork, protecting H2O, Fire Training

Watts model 009M2 RPZ for high-hazard apps. on the r. On the l is a Badger water meter w/integral strainer.
Watts model 009M2 RPZ for high-hazard apps. on the r. On the l is a Badger water meter w/integral strainer.

Low degree hazard backflow w/vent

Good for boilers with drain nearby otherwise use dual check w/o vent.
Good for boilers with drain nearby otherwise use dual check w/o vent.

Dual check made by Watts (7D)

Steam generating equipment, such as boilers, require backflow prevention due to the degradation of water quality.
Steam generating equipment, such as boilers, require backflow prevention due to the degradation of water quality.

Testing and repair of backflow preventers

The backflow preventer has moving parts, and therefore just as automobiles and houses need repair, the same goes for these pollution prevention control apparatus. Once every 365 days these assemblies that are testable, need to have done just what the description implies, they need to be tested. The purpose of this test is to interpret from the results of the test whether or not the backflow is working properly.

If they are found out to have failed, they will need to be cleaned and/or repaired and re-tested until they pass the test. Many plumbing companies are able to provide this service, and depending on your state or countries plumbing codes, perhaps fire sprinkler and/or landscape irrigation contractors might also do the same.

More by this Author


Comments 3 comments

Suzy Frame 3 years ago

Thanks so much for sharing this information! I have been looking into a lot of different methods or options I have with plumbing! I have been looking into plumbers edmonton canada and what help thy can offer! I have been amazed at what I have found! This website has also been helpful as well: www.thegentlemenplumbersedmonton.com


4FoodSafety profile image

4FoodSafety 3 years ago from Fontana, WI

When did back flow preventers enter the water utility market? The 1990 or the 1980s. Why were we so slow to adapt?

So glad you have written this. Water is taken for granted and never fully understood. Your photos were priceless.

Voted up!


noturningback profile image

noturningback 3 years ago from Edgewater, MD. USA Author

Thank you Suzy and 4FoodSafety. I am providing this link http://www.ci.manhattan.ks.us/DocumentCenter/Home/...

for further reflection on backflow prevention/cross-connection incidents and remedies.

Awareness of contamination/pollution of water supplies has been known for over 150 years. From Wikipedia: In 1854, the British physician John Snow found that cholera was spread through contaminated water. As a result of his findings, several cities began to treat all water with sand filters and chlorine before distributing it to the public

The need for backflow prevention may not seem obvious, but it is an unseen bacteria or poison that will result in illness and sometimes fatalities. At what cost do we declare them necessary or not?

As far as the first backflow preventer, I can't put my finger on them, but there are many manufacturers and they made preventers for sale back in the 1970s and perhaps the 60's too.

I worked at a hospital that had constructed a barometric loop to prevent backflow from back-siphonage built in the 1920s @ Crownsville Hospital Center; Crownsville, Maryland; USA

Thanks again for the comments and let's do our part to keep our water safe now and for the future.

    Sign in or sign up and post using a HubPages Network account.

    0 of 8192 characters used
    Post Comment

    No HTML is allowed in comments, but URLs will be hyperlinked. Comments are not for promoting your articles or other sites.


    Click to Rate This Article
    working