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What is it?   Where is it?

And why do I have to pay to have it tested?


1. Backflow prevention is to stop dirty or contaminated water from flowing backward from your sprinkler system into the clean/potable water provided by the municipality. It is a special device that prevents water from flowing backward.


2. This device is usually located near the water meter but in the

case of an above ground device it may be secluded behind hedges or in a planting bed.


3. These devices though design to very high standards can age and malfunction, therefore you are required to test the device annually to assure it is functioning. Municipalities are like the phone company they provide and guarantee service to your home, any equipment attached to the system belongs to you. You are required to maintain your equipment. Since this is a public health issue, you are required to assure it is functioning properly and test it annually.


Technicians are trained, certified and licensed to test the devices and they are required to re-certify each year. Since a few germs or a little toxic water could kill you, this is a serious matter.


Three types of devices.

Different Municipalities require different types of devices however the testing of these devices is a Texas Commission of Environmental Quality requirement.


Double Check Valve

This is a double check valve. This is two redundant valves that allow water to flow in a forward direction only. Shown are the multiple test points for testing the functionality of the valves.


RP Valve (Reduced Pressure Principle Double Check Valve)

Similar to the Double Check valve except that a third valve is between the two check valves. If the supply pressure drops and the water attempts to flow backward the third valve opens to the atmosphere and drains the dirty water to the ground.


PVB (Pressure Vacuum Breaker Valve)

Most common is the PVB. It is required to be mounted above the ground, one foot higher than the highest sprinkler head. It has only on valve. When the water is flowing in a forward direction the valve opens to the system. When water stops flowing in a forward direction the valve closes to the system and opens to the atmosphere, any backflow will discharge to the ground.



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