Cross Connection Control

We are all connected to the same public drinking water system

A cross connection is a link between a possible source of pollution and a potable water supply. A pollutant may enter the potable water system when the pressure of the pollution source exceeds the pressure of the potable water source or when a sudden loss of pressure occurs in the water system and backflow occurs

Backflow or backsiphonage occurs when water flows backward through the water supply system. When the water is accidentally mixed with hazardous chemicals or bacteria, it is dangerous!

How does contamination of water occur?

Water normally flows in one direction, from the public water system through the customer's plumbing to a plumbing fixture. Under certain conditions water can flow in the reverse direction. Potentially contaminated water from a customer's premise may backflow through an unprotected cross connection and enter the public water sypply. There are two types of backflow - backsiphonage and backpressure.

What are some common areas where cross connections are a concern?

  • Hose bibbs
  • Boiler
  • Cleaning/Mop Stations
  • Lawn Irrigation Systems
  • Fire Protection Systems
  • Lab and Medical Equipment
  • Photo Developing Equipment

How do we keep the water safe?

Bloomington Township Public Water District is required by State Regulations to have a plan and process to identify unprotected cross connections, and to ensure they are eliminated or protected with an approved backflow preventer to protect the public water supply. Some backflow preventers, or backflow prevention assemblies, require annual testing to ensure they are in proper working condition.

What must I do to help prevent contamination of drinking water and protect the water supply?

As required by State Regulations, Bloomington Township Public Water District will be mailing out Cross Connection Control Survey Questionnaires that must be completed by you - the water customer, and returned to the Water District. You may return the questionaire to the District office at 1717 RT Dunn Drive, or mail it to PO Box 704, Bloomington, Illinois, 61702.

What if I have a backflow prevention assembly?

BTPWD will send you a notice instructing you to have your backflow prevention assemblies tested for performance. These assemblies must be tested every year. You may typically find assemblies on supplies to main service lines to a buildling, irrigation system, fire sprinkler system, boiler or other equipment.

What else can I do to protect the drinking water supply?


  • Complete the required Cross Connection Control Survey Questionnaire provided by BTPWD.
  • Keep the ends of your hoses clear of all possible contaminants and...
  • If not already equipped with an in-line protection device, buy and intall an approved hose bibb vacuum breaker on all threaded faucets. (These devices do NOT require testing).
  • Have all backflow prevention assemblies tested every year.
  • Contact BTPWD with any questions you may have about plumbing or equipment connections.


  • Submerge hoses in buckets, vats, tubs, sinks, or ponds.
  • Use spray attachments or valved spray hoses without a backflow preventer.
  • Directly connect waste drain pipes from water softeners or other treatment systems to the sewer system. All drains should be air gapped.

This information may seem overwhelming until you have some examples of what could happen.  Here are some examples:

1.  Unwanted Guests (residents find parasites in tap water) Oct. 1991 (Southgate, Michigan).  Parasitical worms were found in the water at two homes after a malfunctioning lawn sprinkler coupled with a water main break sucked nematodes into the water system.  The nematodes first showed up in the evening of Oct. 1 after the backflow prevention system on the privately owned underground sprinkler malfunctioned.  When the water pressure dropped, the vacuum in the system sucked some water from the sprinkler into the City water.  A homeowner found the worms swimming around in his bathtub when he started filling the tub for his child.  He said he was appalled to find the critters, as well as rust and other debris in his water.  "The only reason I noticed it is because I have children and was giving my kid a bath.  If you have a screen on your faucet or you were taking a shower, you wouldn't see it."  The contractor who installed the sprinkler system didn't pull a city permit and used a "cheap" atmospheric vacuum breaker.  When it malfunctioned, which was at the time of the water main break, the nematodes were pulled right in.

2.  Heating System Anti-Freeze Into Potable Water.  Bangor Maine Water Department employees discovered poisonous antifreeze in a homeowner's heating system and water supply in November, 1981.  The incident occurred when they shut off the service line to the home to make repairs.  With the flow of water to the house cut off, pressure in the lines in the house dropped and the anti-freeze, placed in the heating system to prevent freeze-up of an unused hot water heating system, drained out of the heating system into house water lines, and flowed out to the street.  If it had not been noticed, it would have entered the homeowner's drinking water when the water pressure was restored.

3.  Kool-Aid Laced With Chlordane.  In August, 1978, a professional exterminator was treating a church located in a small town in South Carolina, for termite and pest control.  The highly toxic insecticide chlordane was being mixed with water in small buckets, and garden hoses were left submerged in buckets while the mixing was being accomplished.  At the same time, water department personnel came by to disconnect the parsonage's water line from the church to install a separate water meter for the parsonage.  In the process, the water was shut off in the area of the church building.  Since the church was located on a steep hill, and as the remaining water in the lines was used by residents in the area, the church was among the first places to experience a negative pressure.  The chlordane was quickly siphoned into the water lines within the church and became mixed with the Kool-Aid being prepared by women for vacation bible school.  Approximately a dozen children and three adults experienced dizziness and nausea.  Fortunately, none required hospitalization or medical attention.