Backflow - Frequently Asked Questions

A cross-connection is a physical connection between drinkable (potable) water and an actual or potential contamination hazard that could make the water unsafe to drink. Wherever there is a cross-connection, there is a potential threat to public health from contaminants.

Examples of cross-connections:

• Private wells: Connected to a service line receiving water from a public water supply – untreated water could be pumped into the drinking water supply which serves the home and the public water system
• Lawn sprinkler systems: Stagnant/contaminated water from the sprinkler system could be drawn into the water system
• Common garden hose: Connected directly to hose-end sprayer to apply pesticides or fertilizer, laying it in a swimming pool, chemical/storage tank or puddle of water that can enter the water distribution system

Water flowing opposite to its intended direction, either from a loss of pressure in the supply lines or an increase in pressure on the customer’s side. When the water backflows, it could carry contaminants with it into the water lines. The two types of backflow are backpressure and backsiphonage.

Backpressure occurs when the downstream pressure (from the customer's side) is greater than the water supply pressure. This could push contaminated water into the public water system.

Reductions in drinking water supply pressure occur during events such as waterline flushing, firefighting or breaks in water mains.

Backsiphonage is caused by negative pressure in a public water system or customer’s drinking water system. It's possible for contaminants to be pulled in at this point because the normal flow is reversed.

This can occur when there is a stoppage of water supply, such as from water main breaks, or when there is a concentrated use of water in one location, such as from firefighting. 

A backflow prevention assembly is an approved, testable assembly that uses valves to prevent potential contaminants from passing into the drinking water system.

Does a lawn irrigation system require a backflow prevention assembly?

Yes, because lawn irrigation systems can backflow contaminated water into the drinking water system.

The International Plumbing Code (section 608.16.5) states that the drinking water supply to lawn irrigation systems shall be protected against backflow by a pressure-type vacuum breaker, a double-check valve assembly or a reduced pressure backflow preventer depending on the degree of the site hazard.

How often does the backflow prevention assembly need to be tested?

In order to insure the proper operation of a backflow prevention assembly, it must be tested and certified upon installation and certain backflow prevention assemblies in health hazard environments shall be tested at least once a year thereafter by a licensed backflow tester. Mechanical backflow prevention assemblies have internal seals, springs and moving parts that are subject to fouling, wear or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed. Therefore, all backflow prevention assemblies should be tested periodically to ensure that they are functioning correctly. Mechanical backflow prevention assemblies have to be tested with properly calibrated gauge equipment.

The air gap is an unobstructed distance between the lowest opening from any pipe or faucet conveying water to a tank, fixture, sink or other assembly and the flood level rim or overflow of the receptacle. It offers a complete physical separation between the water supply and the receiving vessel in order to protect against backflow. This is considered the most effective form of backflow prevention. E.g. Sink (the space between the faucet and the drain is the air gap)

What are some potential hazards?

Potential threats to the drinking water system will require a backflow prevention assembly. Common examples include:

• Fire protection systems
• Irrigation systems
• Marinas
• Restaurants
• Hospitals
• Manufacturers

The purpose of a CSI is to identify if there is a presence of actual or potential sources of contamination in the drinking water system. There are two sources of contamination: cross-connection and lead plumbing.

What happens during a Customer Service Inspection?

Once a time and date have been agreed upon, the inspector will walk the exterior and interior of the facility with a designated representative to look at any point of use of the private water system. The inspector will give live feedback of any concerns or cross connections found during the inspection.

A lead swab test will also be conducted during the inspection to verify that lead pipe or solder is not present within the facility. The inspector will need to see any backflow devices within the facility, such as bathrooms, kitchens, hose bibs, chemical rooms and any other areas that have access to the water system.

After the inspection is complete, the inspector will fill out the Customer Service Inspection Certificate (form provided by TCEQ). This form will be attached with a letter explaining if any violations were found and the corrective action needed. These two documents will be mailed to the customer and if corrections were to be made, then a follow-up inspection will be conducted once the corrections have been made. After the follow-up inspection is completed and the violations are corrected, then a compliance letter will be mailed to the facility to inform them that they are now compliant.

What are the concerns with lead plumbing?

The Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) agree on the health risks of lead plumbing. Lead is harmful to health, especially for children. Additional information concerning the risk with lead plumbing can be found here and here.    

A TCEQ-approved and licensed Backflow Prevention Assembly Tester (BPAT) and registered with Vepo LLC.

• Approved backflow testers in San Angelo