What the heck is it? Anti-siphon/External Vacuum Breaker Devices

Submitted by DonHester on Wed, 11/26/2014 - 17:06.

What the heck is it? Anti-siphon/External Vacuum Breaker Devices

So as home inspectors one thing we are looking for are these mysterious little gadgets called a Vacuum Break or Anti-Siphon device on our exterior hose bibb/sillcocks.

These external vacuum breakers are required at all hose bibbs/sillcocks. If they do not already have one built in you will need to add a screw on type of vacuum breaker.

Hose bibb with integrated vacuum breaker

Hose bibb with concealed Vacuum Breaker

Another example of concealed vacuum breaker

Here are a couple of examples of screw on vacuum breakers.

Typically these devices are designed with a spring loaded check valve that when the water is turned off the device vents to the atmosphere preventing backsiphonage.

Most people/homeowners do not know if they have one installed or not and what the real purpose is for.

The purpose of all of this is to prevent potential cross contamination or cross connection. This is a connection that has the potential physical connection between the water supply and any non-potable fluid, solid or gas.

The potential with a hose bibb is that if you had the hose connected and something happened that created back siphonage or backflow you could potentially suck contaminated fluids (solids or gases) back into the water supply.

What could cause this? There are a few things that can cause this, a break in the water service, a sudden drop in pressure from high water withdrawal (like from fire fighting activities), when the municipality performs flushing of mains and/or reduced supply pressure on the suction side of a booster pump.

Now granted not all of these are going to be common, but protected the water supply is a growing concern in many municipalities.

As for most plumbing codes it aimed at health and safety. Keep the bad stuff in its place and away from what we will drink and cook with.

So when it comes to these specific devices we have some plumbing codes that we should pay attention to as home inspectors.

2012 UPC (Universal Plumbing Code)

603.5.7 Outlets with hose attachments.

Potable water outlets with hose attachments, other than water heater drains, boiler drains, and clothes washer connections, shall be protected by a non-removable hose bibb type backflow preventer, a non removable hose bibb type vacuum breaker, or by an atmospheric vacuum breaker installed not less than 6 inches (152 mm) above the highest point of usage located on the discharge side of the last valve. In climates where freezing temperatures occur, a listed self-draining frost-proof hose bibb with an integral backflow preventer or vacuum breaker shall be used.

2012 IRC (International Residential Code)

P2902.4.3 Hose connection.

Sillcocks, hose bibbs, wall hydrants and other openings with a hose connection shall be protected by an atmospheric-type or pressure-type vacuum breaker or a permanently attached hose connection vacuum breaker.

Exceptions:

1. This section shall not apply to water heater and boiler drain valves that are provided with hose connection threads and that are intended only for tank or vessel draining.

2. This section shall not apply to water supply valves intended for connection of clothes washing machines where backflow prevention is otherwise provided or is integral with the machine.

(It should be noted that a hose bibb vacuum breaker style of anti-siphon should never be subjected to continuous pressure (typically considered 12 hours or more at a time)).

Informational Link for Washington State-
http://www.doh.wa.gov/portals/1/documents/4200/contamination.pdf

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What the heck is it? Anti-siphon/External Vacuum Breaker Devices