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Cross Connection and Backflow Prevention

What is a cross-connection?

A cross-connection is any temporary or permanent connection between a public water system or consumer's potable (i.e., drinking) water system and any source or system containing non-potable water or other substances. An example is the piping between a public water system or consumer's potable water system and an alternative water system, cooling system, or irrigation system.

What is backflow?

Backflow is the undesirable reversal of flow of non-potable water or other substances through a cross-connection and into the piping of a public water system or consumer's potable water system. There are two types of backflow... backpressure backflow and back-siphonage.

What is backpressure backflow? 

Backpressure backflow is backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer's potable water system. Backpressure (i.e., downstream pressure that is greater than the potable water supply pressure) 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 water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains.

What is back-siphonage?

Back-siphonage is backflow caused by a negative pressure (i.e., a vacuum or partial vacuum) in a Public water system or consumer'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.

Why does the Austin Water Utility need to control cross-connections and protect its public water system against backflow?

Backflow into a public water system can pollute or contaminate the water in that system (i.e., backflow into a public water system can make the water in that system unusable or unsafe to drink), and each water supplier has a responsibility to provide water that is usable and safe to drink under all foreseeable circumstances. Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink. For these reasons, the Austin Water Utility must take precautions to protect its public water system against backflow.

What should a water supplier do to control cross-connections and protect their public water systems against backflow?

The Texas Commission on Environmental Quality gives public water suppliers two options: 1. Require a backflow prevention assembly at each service connection that may create a threat to the public water supply. 2. Require backflow prevention assemblies and assemblies within a premises as outlined in the state required plumbing codes. The water suppliers usually do not have the capability to repeatedly inspect every consumer's premises for cross-connections and backflow protection. Generally, this would include the water service connection to each dedicated fire protection system or irrigation piping system and the water service connection to each of the following types of premises: (1) premises with an alternative or reclaimed water system; (2) industrial, medical, laboratory, marine or other facilities where objectionable substances are handled in a way that could cause pollution or contamination of the public water system; (3) premises exempt from the State Plumbing Code inspection and premises where an internal backflow prevention assembly required under the State Plumbing Code is not properly installed or maintained; (4) classified or restricted facilities; and (5) tall buildings.

Where can I get more information about cross-connection control?

One excellent reference manual is the fourth (2015) edition of the American Water Works Association's (AWWA's) Manual M14, Recommended Practice for Backflow Prevention and Cross-Connection Control, which is available from the AWWA Bookstore; 6666 West Quincy Avenue; Denver, Colorado 80235; 800/926-7337; http://www.awwa.org (Exit to AWWA). Another excellent reference manual is the tenth (2009) edition of the University of Southern California's Manual of Cross-Connection Control, which is available from the Foundation for Cross- Connection Control and Hydraulic Research; University of Southern California; KAP-200 University Park MC-2531; Los Angeles, California 90089-2531; 213/740-2032; http://www.usc.edu/dept/fccchr (Exit to USC).

Backflow Preventers

What is a backflow preventer?

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

What is an air gap?

An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against backpressure backflow or back-siphonage but is not always practical and can easily be bypassed.

air gap

What is a reduced principle backflow assembly (RPBA)?

An RPBA is a mechanical backflow prevention assembly that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RPBA is effective against backpressure backflow and back-siphonage and may be used to isolate health or non-health hazards.

RPBA

What is a pressure vacuum breaker assembly (PVB)?

Two styles of PVBs are available: (1) Pressure Vacuum Breaker and (2) Spill Resistant Vacuum Breaker. A PVB is a mechanical backflow prevention assembly that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded, air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A PVB may be used to isolate health or non-health hazards but is effective against back-siphonage only.

PVB image

What is a double check valve assembly (DCVA)?

A DCVA is a mechanical backflow prevention assembly that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DCVA is effective against backpressure backflow and back-siphonage but should be used to isolate only non-health hazards.

DCVA

Why do backflow preventers have to be tested periodically?

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 if installed to protect form a health hazard situation. The Texas Commission on Environmental Quality and local water suppliers oversee these state requirements. 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 properly. Mechanical backflow prevention assemblies have to be tested with properly calibrated gauge equipment.

Why does a soft drink dispensing machine require backflow protection?

Soft drink dispensers (post-mix carbonators) use carbonated water mixed under pressure with syrup and water to provide soft drinks beverages. Many, if not most, water pipes are made of copper. When carbonated water comes into contact with copper it chemically dissolves the copper from the pipe. Ingesting large amounts of copper can cause acute gastrointestinal distress, vomiting, and diarrhea. The Austin Plumbing Code requires that the approved backflow prevention for a post-mix carbonator be a reduced pressure backflow assembly (RPZ). Additional requirements: no piping containing copper shall be installed downstream of the RPZ backflow assemblies supplying carbonators.

Water Wells

What is the purpose of registering water wells?

The City of Austin adopted the Water Wells Ordinance (Chapter 15-12 of the Austin City Code) to ensure that public and private potable water systems are not interconnected with any public or private potable water system without necessary backflow prevention controls. This ordinance is intended to prevent threats to public health and safety by making sure that all trade permits (plumbing and electrical permits) are obtained as required. An up-to-date registry of water wells also enables better tracking of water well locations within the City for potential further study of groundwater use and quality issues within our community.

What is considered a “New” water well?

A water well is considered “New” if the drilling, re-drilling, plugging or capping is completed after the effective date of the ordinance - October 22, 2012. For all such new water wells, an Advance Notice of Water Well Activity Form must be submitted no fewer than five (5) business days before the regulated water well activity. After completion, each owner of a new water well is also required to submit the Water Well Registration Form with required attachments no more than 70 days after the water well is completed. 

Wells completed before October 22, 2012 were required to have been registered by April 20, 2013.

What needs to be done before drilling a new water well?

Before a new water well is drilled or an existing water well is re-drilled, plugged or capped the property owner shall provide the director advance notice prior to starting the work. This Advance Notice of Water Well Activity Form must be completed by the owner and submitted no fewer than five (5) business days prior to any work on a water well.

Is there a grace period to register an existing water well?

The Director may allow a person a longer period within which to register an existing water well for good cause as determined by the Director. See section 15-12-21 of the regulations.

What types of water wells need to be registered?

A Water Well Registration Form is required for each of the following types of water wells: 

  • Domestic
  • Public Supply
  • Industrial
  • Stock
  • Irrigation 

Registration is not required for:

  • Injection wells
  • Geothermal wells
  • De-watering wells
  • Test wells
  • Monitoring wells
  • Environmental soil boring projects
What type of documentation is required to be submitted?

A copy of the property plat showing location and a State of Texas Well Report.

If a registration is completed for a company, do all other well drillers employed by the company also need to register?

Yes, each water well driller is required to register with the city as a requirement of drilling constructing, repairing, plugging or capping any new or existing water well or installing or repairing any water well pump. Please refer to the Water Well Driller and Water Well Pump Installer Registration Form.

Will licensed pump installers need electrical and plumbing permits?

Any type of alterations to water well shall be done so in conformance with all relevant city code provisions, including but not limited to:

Where can I get more information about water wells?

Please contact the Austin Water Special Services Division.

  • Email: waterwell@austintexas.gov  
  • Phone: 512-972-1060 (option 5 – Industrial Waste/Water Protection, then option 1 – Water Protection/Cross Connection)