Division of Water : Associations
The Bluegrass Cross-Connection Prevention Association (BGCCPA) has a board that certifies backflow prevention device testers. The members are an alliance of individuals with the common interest of protecting public water supplies from contamination through cross-connections. The membership is represented by plumbers, sprinkler system contractors, irrigation specialists, public and private water and wastewater system operators, architects, engineers, governmental officials and general industry.
In Kentucky, all cross-connections are prohibited as stated in public water supply regulation. 401 KAR 8:020, Section 2: “All cross-connections are prohibited. The use of automatic devices, such as a reduced pressure zone back flow preventer or vacuum breaker, may be approved by the cabinet in lieu of proper air gap separation. A combination of air gap separation and automatic devices shall be required if determined by the cabinet to be necessary due to the degree of hazard to public health. Every public water system shall determine if or where cross-connections exist and shall immediately eliminate them.”
All municipalities with public water supply systems should have cross-connection control programs. Those responsible for institutional or private water supplies should also be familiar with the dangers of cross-connections and should exercise careful surveillance of their systems.
What is a cross connection?
Simply put, a cross-connection is any connection to a drinking water supply. These connections may be temporary or permanent between a public water distribution system and any other system containing non-potable water or other substances. The most common cross-connection in the home is the garden host attached to the outside faucet. The outside faucet requires a mechanical protection device such as a host bib vacuum breaker to prevent possible contamination of the public water supply. Hardware stores sell the home outside faucet assembly with the built-in vacuum breaker.
Defined in Kentucky Administrative Regulation [401 KAR 8:010, Section 1 (14)], cross-connections are physical connections or arrangements between two otherwise separate systems, one of which contains potable water and the other being either water of unknown or questionable safety (or steam, gas or chemicals), whereby there may be flow from one system to the other, the direction of flow depending on the pressure differential between the two systems. As an example, a public water system must not be connected to a private water system or auxiliary water supply without safety devices installed to prevent contamination of the potable water.
Consider this scenario
It’s a hot, sunny, water-using day. You’ve decided it’s time to use the garden hose to spray pesticide on your lawn.
Attached to your garden hose is one of those handy bottles that applies the pesticide at the proper rate and dosage when you turn on the faucet. You’ve taken all the right precautions to prevent yourself from being contaminated by the pesticide by wearing a respirator and gloves. You’re spraying the pesticide on your lawn when suddenly your teenager decides to take a midday shower and your spouse turns on the dishwasher and does a load of laundry. The high use of water from your home results in negative reverse flow, allowing the pesticide to be sucked into your home water supply to poison you.
While you are spraying the pesticide on the lawn, a fire erupts down the street. There is a sudden drop in water pressure as water pressure as water is rapidly pulled out of the mains from the fire department. The pesticide in the garden hose is then drawn into the water mains beyond your home, contaminating the water and causing the entire neighborhood to become suddenly ill and possibly causing death.
A properly installed protective backflow (or back-siphon age) valve could have prevented the contamination and ensuing harm. To prevent contamination from a home faucet, each outdoor spigot should have a hose-bib vacuum breaker installed.
Defined as actual or potential connections between a potable and non-potable water supply. Cross-connections constitute a serious public health hazard, particularly when industry, hospitals, nursing homes or funeral homes do not have adequate cross-connection safety devices installed. There are numerous well-documented cases in which cross-connections have been responsible for contamination of drinking water that, when consumed, caused the spread of disease and even death.
What is backflow?
Backflow means the reversal of water flow from its normal or intended direction of flow. Whenever a water utility connects a customer to the utility’s distribution system, the intention is for the water to flow from the distribution system to the customer.
However, the flow of water could be reversed from the customer back into the distribution system. If cross-connections exist within the customer’s plumbing system when backflow occurs, then it is possible to contaminate the public water supply. There are two types of backflow – backpressure backflow and back-siphon age.
What is backpressure backflow?
Backpressure backflow occurs when the pressure of the non-potable system exceeds the positive pressure in the water distribution lines; that is, the water pressure within an establishment’s plumbing system exceeds that of the water distribution system. For example, there is a potable water connection to a hot water boiler system that is not protected by an approved backflow preventer. If pressure in the boiler system increases to a point that it exceeds the pressure in the water distribution system, a backflow from the boiler to the public water system may occur.
A downstream pressure that is greater than the potable water supply pressure causes backpressure backflow. Backpressure can result from an increase in downstream pressure, a reduction in the potable water supply pressure or a combination of both. Boiler pumps, pressure pumps or temperature increases in boilers can create increases in downstream pressure. 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-siphon age?
Back-siphon age occurs when there is a partial vacuum (negative pressure) in a water supply system, which draws the water from a contaminated source into a potable water supply. The water pressure within the distribution system falls below that of the plumbing system it is supplying. The effect is similar to siphoning or drinking water through a straw. For example, during a large fire, a pump is connected to a hydrant. High flows pumped out of the distribution system can result in significantly reduced water pressure around the withdrawal point. A partial vacuum has been created in the system, causing suction of contaminated water into the potable water system. During such conditions, it is possible for water to be withdrawn from non-potable sources located near the fire – for example, air-conditioning systems, water tanks, boilers, fertilizer tanks and washing machines – into buildings located near a fire. The same conditions can be caused by a water main break.
Garden hoses, toilets or similar devices create most household cross-connections. Under certain conditions, the flow in household water lines can reverse and siphon contaminates into the water supply. A toilet installed incorrectly without a “plumbing-code approved” toilet ballcock (air gap) will allow contaminated water to backflow to other water outlets in your house, including the kitchen sink.
What is a backflow Preventer?
A backflow preventer is a method or mechanical device to prevent backflow. The basic method of preventing backflow is an air gap, which either eliminates a cross-connection or provides a barrier to backflow. Mechanical backflow preventers are devices that provide a physical barrier to backflow. There are four devices commonly used – the reduced pressure principle assembly, the double check valve assembly, the pressure vacuum breaker and the atmospheric vacuum breaker. All of these devices require periodic maintenance and testing.
Kentucky plumbing codes and standards [815 KAR 20:120, Section 2 (7)] for backflow preventers include:
- Air gap
- Reduced pressure principle back pressure backflow preventer
- Double check valve assembly
- Pressure type vacuum breaker
- Atmospheric type vacuum breaker
- Barometric loop
Other types of mechanical devices, such as the barometric loop, superior pressure type device or the venturi type vacuum breaker, are used for backflow prevention.
The double check valve assembly was one of the first designs during the early 1900s to prevent backflow. Improvements in the early designs of double check valve assemblies ranged from the early metal-to-metal seats to resilient facing on the clapper 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-siphon age, but is not always practical and can easily be bypassed.
In Kentucky, refer to plumbing regulations in 815 KAR 20:120, Section 2 (7)(a) for specific uses of air gaps.
What is a Reduced Pressure Principle Assembly (RP or RPBA)?
An RP is a mechanical backflow preventer 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 RP is effective against backpressure backflow and back-siphon age and may be used to isolate health or non-health hazards.
The RP may be used on all direct connections which may be subject to backpressure or back-siphon age and where there is the possibility of contamination by the material that does constitute a potential health hazard. A health hazard or high hazard is a cross-connection involving any substance that could cause death, illness, spread disease or have a high probability of causing such effects. The degree of hazard refers to a contaminant being toxic on nontoxic, whereby a health hazard involves a toxic substance.
In Kentucky, refer to plumbing regulations in 815 KAR 20:120, Section 2 (7)(c) for specifics on a DC. Applicable to low level of hazard back pressure backflow conditions.
Are a Double Check and Dual Check Backflow Preventer the same thing?
They sound very similar, and they are “relatives,” but they are not the same. A Double Check will ALWAYS have two manual shutoff valves – one on the inlet and one on the outlet. These manual valves are used as emergency shut-offs and are also necessary to properly test the operation of the backflow preventer. A Double Check will also have test cocks (small outlets) for connecting the test gauges. If it doesn’t have those shut off valves and test cocks, it is NOT a Double Check Backflow Preventer.
A dual check is more of a flow-control device rather than a backflow preventer. Dual check devices do not have shut-off valves or test cocks.
What is a Pressure Type Vacuum Breaker (PVB)?
A PVB is an assembly consisting of an independently operating, internally loaded check valve and an independently operating, loaded air-inlet valve located on the discharge side of the check valve. The device includes tightly closing shut-off valves on each side of the check valves and properly located test cocks for the testing of the check valve(s).
PVBs may be used as protection for connections to all types of non-potable systems where the vacuum breakers are not subject to backpressure. These units may be used under continuous supply pressure. They must be installed above the usage point. This type of vacuum breaker can be used for lawn sprinkler systems under continuous pressure. Therefore, if properly installed, it will protect the potable water supply. The device shall be installed 12 inches above the highest sprinkler head.
In Kentucky, refer to plumbing regulations in 815 KAR 20:120, Section 2 (7)(d) for specifics on pressure vacuum breakers. Applicable to back-siphon age conditions.
What is an Atmospheric Type Vacuum Breaker (AVB)?
The purpose of the AVB is to prevent a siphon from allowing a contaminant or pollutant into the potable water system. They do not prevent backflow from backpressure.
The most commonly used atmospheric type anti siphon vacuum breakers incorporate an atmospheric vent in combination with a check valve. Its operation depends on a supply of potable water to seal off the atmospheric vent, admitting the water to downstream equipment. If a negative pressure develops in the supply line, the loss of pressure permits the check valve to drop, sealing the orifice, while at the same time the vent opens, admitting air to the system to break the vacuum. AVBs can be used on most inlet type water connections which are not subject to backpressure, such as low inlet feeds to receptacles containing toxic and nontoxic substances, valve outlet or fixture with hose attachments, lawn-sprinkler systems and commercial dishwashers.
In Kentucky, refer to plumbing regulations in 815 KAR 20:120, Section 2 (7)(e) for specifics and critical level settings for atmospheric type vacuum breakers. Applicable to back-siphon age conditions.
What is a Barometric Loop?
A barometric loop is a looped piping arrangement 35 feet (11 meters) in height in which the water flow goes over the loop at the top. This method of backflow prevention is only capable of protecting against back-siphon age, since backpressure could drive water backward over the loop.
In Kentucky, refer to plumbing regulations in 815 KAR 20:120, Section 2 (7)(f) for specifics on barometric loop. Applicable to backsiphonage conditions. The use of a barometric loop shall not be acceptable as the primary back siphon age preventer.
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