The United States Environmental Protection Agency (EPA) defines a cross-connection as “actual or potential connections between a potable and non-potable water supply.” Therefore, all service lines attached to a public water system are cross-connections. According to the Safe Drinking Water Act, all industrial and commercial customers must install backflow prevention systems to avoid potentially harmful contamination of our drinking water supply. As a result, the EPA is enforcing the mandate for all industrial, all commercial and residential customers. Because of the potential dangers to you and other water customers from a backflow incident, it is necessary to eliminate cross-connections by installing backflow prevention devices.

Cross-Connections can be found in many places within a plumbing system. Here are some common cross-connections:

• Hose Bibb Connections - 70% or more of all backflow incidents occur through hose bibbs
• Auxiliary Water Systems - Those individuals that have private wells or springs and are also connected to the public water system
• Ball Cock Fill Valves In Toilet Flush Tanks - All ball cock valves should have anti-siphon valves on them to prevent backsiphonage
• Inlet Fill Lines - For HVAC systems and boilers
• Portable Water Priming Lines - For pumps that pump hazardous substances
• Flushing Lines - For grease traps and other equipment
• Fire - Sprinkler systems and non-potable fire storage tanks
• Irrigation - For irrigation systems including lawn sprinklers
• Process Water and Cooling Water - Used for many reasons

Your current water distribution system is designed so that water flows from the water main through a service line to your site. However, certain conditions can cause water to flow from your plumbing back into the distribution system and the local public water supply, creating a potentially hazardous backflow incident.

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Backflow is caused by backsiphonage and backpressure. Backsiphonage incidents can occur when water pressure drops in the distribution system, which could siphon water from your plumbing into the distribution system.

Pressure changes occur for a number of reasons, such as:

	Heavy water usage on the system (e.g. fire fighting)
	Unauthorized use of a fire hydrant
	Water main breaks
	Use of your booster-pump

Backpressure incidents can occur when the pressure on your system exceeds the pressure in the distribution system. Examples include a car wash that pumps and re-circulates soapy water, or a manufacturing plant that uses substantial water pressure for production.

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With backflow incidents, a risk of non-potable materials — those not intended for human consumption — flowing back into the local water system exists. This could include, but is not limited to, used water, industrial fluid, chemicals, and fire sprinkler or lawn irrigation water.

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For your safety — and by law — all customers must install and maintain backflow prevention devices on their water systems. In addition, good usage habits can reduce the potential for backflow incidents. For instance, you should never leave a hose submerged in a bucket of non-potable liquid. You should also ensure that the water level in any tank of liquid (bucket, tub, etc.) is below any type of faucet or inlet valve. Doing so will create an “air gap” that can help prevent a backflow incident.

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Yes. The EPA requires that customers install backflow prevention devices. This applies to individual homes, businesses and commercial and industrial establishments. Most backflow prevention devices are required to be tested at least once each year. Aqua is committed to protecting drinking water quality, and has maintained a Cross-Connection Control Program since the mid-1970s.

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The law requires annual testing of all backflow prevention devices. If the test shows that your device is not working properly, the law requires you to make all necessary repairs. All testing must be done by a certified testing technician, typically certified by either the American Society of Sanitary Engineers (ASSE). During the test, a technician will use test gauges to be sure that the backflow device’s check valves are holding.

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 Yes. The most common problem that is likely to arise is called Thermal Expansion.  Thermal Expansion occurs when any substance is heated.  When substances are heated they must have room to expand within the system they are contained.  If there is no room for the substances to expand, pressure could build up to the point where it causes equipment damages or explosions that could cause propoerty damage and/or injury. Since a backflow prevention device creates a closed system the expanded hot water has nowhere to go unless a relief valve or thermal expansion tank is properly installed.  The most common thermal expansion problem is the expansion of water within domestic hot water tanks.

There are other problems that can arise with some types of backflow preventers or from improperly installed devices.  Problems can lead to water leakage and propoerty damage.  That is why it is essential that the individual who installs your backflow prevention device is properly qualified to install your backflow prevention device.

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 Here are 10 major backflow installation device guidelines:

1. Reduced Pressure Principal Assemblies (RP's) and Double Check Valve Assemblies (DCVA's) must be installed a minimum 12" and a maximum of 36" above grade or above finished floor.
2. Unprotected bypasses on all backflow prevention devices are strictly prohibited. Protection on the bypass must be the same as the primary protection.
3. When installing a device, if the test cocks are located on top there should be 12" of clearance between the test cocks and any obstruction.  There should be 24" of clearance if the test cocks are located on the side.
4. RP's must be installed near adequate drainage.
5. Devices must be accessible for testing and repair.
6. Installing RP's in a pit should be avoided.
7. Backflow preventers must only be installed horizontally unless otherwise specified by the manufacturer.
8. Be aware of the properties of the fluids you are dealing with.  For example, are they corrosive or under high pressure?
9. In parallel installations, backflow prevention devices should be the same type, provide the same level of protection, and should have the same size and flow capacity.
10. If an enclosure is used around a backflow prevention device the enclosure must have adequate drainage.  This is often referred to as "bore-site to daylight."