Cross-connection and Backflow Prevention

• Backflow refers to the flow of water or other substances in the opposite direction of the treated drinking water distribution system. Two types of backflow exist back-pressure and back-siphonage.
• Back-pressure occurs when the pressure from the source of contaminants is higher than the positive pressure in the water distribution system. For instance, if a drinking water supply main links to an unprotected hot water boiler system without an approved and functioning backflow preventer, the pressure in the boiler system may surpass that of the water distribution system. This could result in backflow from the boiler to the water supply system.
• Back-siphonage occurs when negative pressure (vacuum or partial vacuum) in the water distribution system, like sipping water through a straw. This can happen during a water main break or when a hydrant is used for firefighting in the drinking water distribution system.

A physical connection between drinkable water and a liquid or gas could make the water unsafe to drink. Whenever there is a cross-connection, there is a potential threat to public health from the liquid or gas contaminants.

For example:

• Garden hose: Knowing the potential for backflow through cross-connections is essential. This can occur when a garden hose is left on and submerged in a container of water or other liquid, which could then be siphoned back into the drinkable water supply.
• Private well: Backflow can happen when an untreated water supply pump, such as a private well, is connected to the drinkable water supply. This could result in untreated water accidentally entering a home's drinkable water and the public water system.
• Lawn sprinkler system: According to TCEQ regulations, all lawn sprinkler systems must have a mechanical backflow prevention assembly for safety. Failure to do so may result in stagnant water from the sprinkler system flowing back into the home water system.

Backflow may affect the drinking water quality in homes, businesses or facilities. It can create health hazards if contaminated water enters the public water and is used for drinking, cooking or bathing.

Backflow events frequently occur, although most do not create health hazards. Unprotected cross-connections with water supply plumbing or public drinking water piping systems are prohibited. Everyone is responsible for protecting the public water supply from backflow that may contaminate our drinking water. It includes complying with the plumbing code and avoiding unprotected cross-connections.

Preventing backflow occurrences is a shared responsibility. State and local-level plumbing inspectors have jurisdiction over plumbing systems inside buildings. In contrast, state regulatory agencies and public water suppliers oversee safeguarding the distribution system at each service connection. Ultimately, water customers carry the responsibility of maintaining their plumbing systems. It is up to the customer to ensure unprotected cross-connections do not arise and that any necessary backflow prevention devices are tested in compliance with state regulations and kept in working order.

Preventing backflow situations in your home and business

• Be aware of cross-connections, and take action to eliminate or isolate them
• Do not submerge hoses or place them where they could become submerged in water or chemicals.
• Use hose bib vacuum breakers on fixtures (hose connections in the basement, laundry room, and outside faucets/spigots).
• Install approved backflow prevention devices on lawn irrigation systems and fire sprinkler system services. We determined the type of preventive devices required based on the potential type of pollutants or contaminants - high, low or moderate. In low-hazard situations, installing a residential dual-check device might be allowed.

It's important to ensure that all cross-connections are properly installed and protected to meet state laws and local plumbing codes (30 TAC Chapter 290), regardless of the building's condition. Additionally, federal law requires water suppliers and companies, such as Brownsville Public Utilities Board, to safeguard their drinking water systems from contamination or pollution caused by backflow through cross-connections.