Frequently Asked Questions

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Why does City of League City need a Cross-Connection and Backflow Testing Program?

The program safeguards the public drinking water and protects the health of its customers by ensuring that any contaminants that could backflow into the public water supply system are isolated within the customer’s internal distribution system.

What is backflow?

Backflow refers to the reverse flow of non-potable water, or other substances, through a cross-connection and into the piping of a public water system or customer’s potable water system. Two types of backflow are backpressure backflow and back-siphonage.

What is a backflow prevention assembly?

A backflow prevention assembly is a means or mechanism to prevent backflow. The basic means for preventing backflow is an air gap, which either eliminates a cross-connection or provides barrier from backflow. The basic mechanism for preventing backflow is a mechanical backflow preventer, which provides a physical barrier to backflow. The principal types of backflow preventers are the reduced-pressure principle assembly, the pressure vacuum breaker assembly and the double check valve assembly.

What is the process for installing/replacing a backflow prevention assembly?

Proper permits must be acquired from the Building Department; to contact their office, 281-554-1429.

Why do backflow prevention assemblies need to be tested?

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 have to be tested periodically to ensure that they are functioning correctly. Mechanical backflow prevention assemblies have to be tested with properly calibrated gauge equipment.

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 at least once a year thereafter by a licensed backflow tester.

How can I contact a licensed backflow assembly tester?

View a list of licensed testers (PDF).

When requesting a test for my backflow prevention assembly, how much should I expect to pay for this service?

It is our understanding that fees range from $50 each for multiple locations for the same customer up to $200 for a single location; so please call around when you are trying to schedule with a tester.

What type of document needs to be returned to the City of League City as proof that testing of the backflow prevention assembly was completed?

The licensed tester will input the approved backflow testing report to BSI, Incorporated database. BSI will notify the City upon input completion. If the customer’s backflow testing report is not inputted into BSI database on or by the due date; then BSI will mail a past due notice to the customer. If the backflow report is not inputted into BSI database two weeks after the due date, BSI will notify the City the customer’s backflow assembly is not in compliance. At which, the City may disconnect the water service until the customer’s backflow device comes into compliance.

How can I verify that testing of my backflow prevention assembly has/has not been completed?

Contact Michael Broussard,
Backflow Program Administrator at 281-554-1266.

Does a lawn irrigation system require a backflow prevention assembly?

Yes. Section 608.16.5, of the International Plumbing Code and Section P2902.5.3 of the International Residential Code (connections to lawn irrigation systems), states that the potable 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 principle backflow preventer – depending on the degree of the site hazard.

How long does a backflow prevention assembly last?

With proper maintenance and annual testing, backflow prevention assemblies have been known to last for many years.

What is considered a potential hazard?

A potential hazard is defined as any possibility of pollutants, contaminants, and system or plumbing hazards. For example, fire protection system, irrigation systems, gasoline refineries and stations, restaurants, hospitals and manufacturers.


Why do residential locations with on-site sewage facility (septic system) and an irrigation system require to have a back flow device and be tested annually?

The existence of a health hazard, such as an OSSF, requires the use of a Reduced Pressure Principle Backflow Prevention Assembly (RPZ) on the irrigation system per:

344.51(d) If an irrigation system is designed or installed on a property that is served by an on-site sewage facility, as defined in Chapter 285 of this title (relating to On-Site Sewage Facilities), then:

  • All irrigation piping and valves must meet the separation distances from the On-Site Sewage Facilities system as required for a private water line in §285.91(10) of this title (relating to Minimum Required Separation Distances for On-Site Sewage Facilities);
  • Any connections using a private or public potable water source must be connected to the water source through a reduced pressure principle backflow prevention assembly as defined in §344.50 of this title (relating to Backflow Prevention Methods); and
  • Any water from the irrigation system that is applied to the surface of the area utilized by the On-Site Sewage Facility system must be controlled on a separate irrigation zone or zones so as to allow complete control of any irrigation to that area so that there will not be excess water that would prevent the On-Site Sewage Facilities system from operating effectively.

Because an RPZ is a mechanical assembly and is subject to fail, it must be tested to make sure it is working properly. The existence of a health hazard necessitates annual testing of the RPZ per:

290.44(h)(4) All backflow prevention assemblies that are required according to this section and associated table located in §290.47(f) of this title shall be tested upon installation by a licensed backflow prevention assembly tester and certified to be operating within specifications. Backflow prevention assemblies which are installed to provide protection against health hazards must also be tested and certified to be operating within specifications at least annually by a licensed backflow prevention assembly tester.

For questions specific to landscape irrigation systems, please contact Ms. Mellissa Keller with the TCEQ Landscape Irrigation Program by calling 512-239-1768 or by emailing Mellissa Keller.

Will an annual inspection continue to be required for backflow prevention assemblies located in the public right-of-way?

Yes. League City will continue to mail out a test due notices and when necessary, test past due notices to all customers with a backflow prevention assemblies. Testing requirements must be completed within 30 days of the test due notice.

What is backpressure backflow?

Backpressure backflow occurs when the downstream side of the piping system is greater than the supply pressure in a public system or customer’s potable water system. Backpressure can result from an increase in downstream pressure, a reduction in the potable water supply pressure or a combination of both. Pumps can create increases in downstream pressure; temperature increases in boilers, etc. Reductions in potable water supply pressure occur whenever the amount of after being used exceeds the amount of water being supplied, such as during waterline flushing, fire fighting or breaks in the water mains.

What is back-siphonage?

Back-siphonage is backflow caused by negative pressure (i.e. vacuum or partial vacuum) in a public water system or customer’s potable water system. The effect is similar to drinking water through a straw. Back-siphonage can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.

What is a cross-connection?

A cross-connection is any temporary or permanent connection between a public water system or the customer’s potable water system and any source or system containing non-potable water or other substances.

Common cross-connections:

  • Private Wells – where the private well connection is connected to a service line receiving water from a public water supply. The untreated water could be pumped into the potable water supply which serves the home and the public water system.
  • Lawn sprinkler systems – where the stagnant/contaminated water from the sprinkler system could be drawn into the drinkable water supply for your home.

Has City of League City process for permitting or overseeing the inspection of new, relocated or repaired backflow prevention assemblies in the public right-of-way changed?

No. League City will continue to review all permits and utility drawings to ensure compliance with backflow prevention requirements, and will continue to oversee the installation and testing of the assemblies.