Reuben Saltzman

Why Do I Need A Vacuum Breaker?

This is one of the most common questions I get from homeowners that I do Truth-in-Housing Evaluations for.  If you’re selling your home in Minneapolis or Bloomington, you will likely hear about this.  A vacuum breaker, commonly referred to as a backflow preventer, is a device that prevents the potable water in your home, and possibly even your neighborhood, from getting contaminated.

How could your water get contaminated? Picture this scenario: I want to mix up some vegetation killer, so I buy the concentrated stuff, pour it into a bucket, then put the garden hose in the bucket to fill it.  I turn the water on, but I get sidetracked with a plumbing project.  I shut off the water to my house, and then open up the laundry faucet to drain the water out of the pipes.  This will create a siphoning effect, which could actually suck the nasty chemicals in the garden sprayer back in to my home, contaminating the potable water.  An even worse scenario would be the city doing work on the water pipes, and the chemical gets siphoned back in to the city’s water supply, contaminating a whole neighborhood.

While these occurrences are not likely, it has happened many times throughout the country, and the cost to fix a contaminated water supply for a city is huge. The cost of a vacuum breaker is very small – about five dollars.  While only Minneapolis and Bloomington enforce vacuum breakers, they’re still required throughout Minnesota by the Minnesota State Plumbing Code, section 4715.2100 (D).

The two most common places where these are installed are at sillcocks (what you connect your garden hose to) and at laundry sink faucets.  An external vacuum breaker is required at sillcocks if they don’t already have one built in.  How do you know the difference?  The photos below show one sillcock with, and one without an integral vacuum breaker.  If a sillcock doesn’t have the little mushroom cap, an external vacuum breaker is required.  At laundry sink faucets, a vacuum breaker is needed if there are threads present that a garden hose could attach to.

For more information on common Truth In Sale of Housing defects, click on any of the links below.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspections


No responses to “Why Do I Need A Vacuum Breaker?”

  1. Craigslist verified accounts
    March 26, 2009, 9:06 pm

    I’m don’t comment often, but I do like your blog

  2. Paul Sorensen
    June 9, 2009, 2:42 pm

    Thanks for the great info. I found your site while trying to figure out what that brass thingy was on our outdoor faucet. Your explanation is fantastic.

  3. Reuben Saltzman
    June 9, 2009, 3:18 pm


  4. Truth-in-Housing Requirements | Reuben's Home Inspection Blog
    November 15, 2009, 7:08 am

    […] Vacuum Breakers – aka backflow preventers.  This is a device that can be purchased at most hardware stores, and should be screwed on to the end of any exterior sillcocks, or indoor faucets that could accept a garden hose thread (typically the laundry faucet).   These are basically one-way valves that protect the city’s water supply from potential contamination.  Note the set screw in the vacuum breaker pictured to the right – this set screw should be tightened down until broken off to make sure the vacuum breaker is permanently installed. […]

  5. lisa
    December 5, 2009, 12:06 am

    Thank you for explaining why the city of warren,MI has a requirement for installing vacuum breakers on sillcocks and laundry tubs. I believe it would require a completely stupid, thoughtless person to actually contaminate their potable water the way you’ve described it (something I’m willing to bet one of the five totally incompetent building inspectors has managed to do) but as improbable as the set of circumstances are that would lead to this you’ve made it make sense to someone with a good understanding of plumbing systems who keept wondering why you would need a vacuum breaker attached to something that closes completely with a valve and has water pressure pushing against it.

  6. A Missing Jumper Wire At The Water Meter | Reuben's Home Inspection Blog
    January 26, 2010, 5:07 am

    […] Vacuum Breakers (backflow preventers) […]

  7. Floor Drain Basics | Reuben's Home Inspection Blog
    March 19, 2010, 11:28 am

    […] Floor Drain Basics […]

  8. Carbon Monoxide Alarm Requirements For Minnesota | Reuben's Home Inspection Blog
    July 9, 2010, 4:06 am

    […] Floor Drains […]

  9. Toilet Repair - Fixing An Improper Air Gap On A Ballcock | Reuben's Home Inspection Blog
    November 29, 2010, 10:56 am

    […] Vacuum Breakers (backflow preventers) […]

  10. Smoke Detector Safety | Structure Tech Home Inspections
    July 11, 2011, 7:50 pm

    […] Vacuum Breakers (backflow preventers) […]

RSS feed for comments on this post. TrackBack URL

Leave a Reply

Notice: Undefined variable: user_ID in /home/structuretech1/public_html/wp-content/themes/bizzyweb-default-2020/comments.php on line 55