How does contamination of water occur?
Water normally flows in one direction from a public water system through a private one, and finally to a plumbing fixture (faucet, garden hose, etc). A pollutant may enter the potable water system if the pressure at the pollution source exceeds the pressure of the potable water source. The reversal of the flow of water is called backflow, and leads to the possible contamination of the public water supply. Backflow may also occur as a result of a sudden loss of pressure in the water system.
What can cause backflow?
Backflow is usually caused by a sudden drop of the water pressure in a public water main. This can create a subatmospheric condition. For example, if the pressure drops in a system while a hose is in a bucket of dirty water, that water could backflow into the public water system, potentially contaminating the water for other users. A drop in pressure could be caused by a variety of things, including a water main break or the loss of power at a pump station.
What can I do to prevent backflow?
- Keep the ends of your hoses free of any possible contaminants
- If your threaded faucets are not equipped with an in-line protection device, install an approved hose bibb vacuum breaker or other backflow prevention devices
- Never submerge hoses in buckets, vats, sinks, tubs or ponds
- Use spray attachments or valve spray hoses that have a devise to prevent backflow
- Do not connect waste drain pipes from water softeners or other treatment systems directly to the sewer system
- All drains should be air gapped
Why do backflow preventers have to be tested?
Mechanical backflow preventers have internal seals, springs and moving parts that are subject to fouling, wear or fatigue. Additionally, mechanical backflow preventers (and air gaps) can be bypassed. All backflow preventers must be tested periodically to ensure that they are functioning properly. A visual check of air gaps is sufficient, but mechanical backflow preventers have to be tested with properly calibrated gauge equipment.
How often do backflow preventers need to be tested?
Backflow preventers must be tested at the time of installation, annually after installation, following any repair work or after relocation of any backflow preventer. Each spring when you start up your lawn irrigation system, make sure that the backflow preventer protecting your drinking water from your lawn irrigation system is properly tested and inspected. Following the testing, a certified plumber must submit a copy of the test report to the City via fax to 847.926.1193 or email to waterplant@cityhpil.com
Who can test the backflow assembly?
Backflow assembly tests in Highland Park can only be conducted by Illinois licensed plumbers who are also certified to inspect backflow assemblies. These plumbers are called Cross Connection Device Inspectors (CCDIs). Please see the following plumber list for CCDIs that have done work in town. Following the testing, a certified plumber must submit a copy of the test report to the City via fax to 847.926.1193 or email to waterplant@cityhpil.com
Do I currently have adequate backflow protection? How can I find out?
If your irrigation system, fire sprinkler system, swimming pool, spa, or other device or appliance plumbed to a water line, was installed with a building permit issued by the City Building Department, adequate backflow protection was required. If you are unsure if backflow protection was properly installed, please contact the Building Division at 847.432.0808.
Option if you cannot test your lawn irrigation system.
We have heard from a number of residents who are unable to perform the Illinois Environmental Protection Agency mandated annual testing of their Cross Connection Control Devices.
On April 23rd, 2013 the City Council authorized implementation of a new protocol that makes provision for this circumstance, sparing residents the expense of activating and testing Cross Connection Control Devices that they do not plan to use. At the owner’s request, City staff will install a specially keyed "Lockout" device that prevents installation or activation of the Cross Connection Control Device, ensuring that inadvertent backflow contamination of the water supply cannot occur, satisfying the IEPA regulation.
This program requires completion of a request form along with an initial fee of $30 to cover the cost of the device. Any devices left in place will incur an annual fee of $30 in subsequent years, invoiced each April.
If you wish to participate in this program, please complete and return the application form along with a $30.00 check payable to The City of Highland Park to the address below:
Water Treatment Plant
1707 St Johns Ave
Highland Park, IL 60035
Who can I contact for additional information?
For additional information, please contact Don Jensen at the City of Highland Park Water Filtration Plant at 847.433.4355.
Where can I find additional information?
The Illinois Environmental Protection Agency has created several informational guides on cross-connections and specific devices and methods used to prevent backflow:
View the EPA's Cross-Connection Control Manual
View the Illinois EPA Cross-Connection Control Summary
View the City Ordinance on Backflow Protection
Participate in the City's Cross-Connection Survey
The City of Highland Park takes pride in providing safe drinking water to our customers. The water that reaches your home or business meets all State and Federal drinking water standards and is safe to drink. However, contamination can occur within your own piping system. The greatest potential hazard is known as an unprotected “cross connection”, which can cause backflow to occur. 
Water is being used in many applications such as mixing, diluting, sprinkling and cleaning. Water is coming into contact with hundreds of chemicals and substances. Under the wrong circumstance, this can lead to water contamination. Loss of water pressure or an improper connection of a pump to a water line could result in dangerous materials being sipohned or pumped back into the water supply. The Cross Connection Control Program requires the installation of backflow prevention devices that are designed to limit the possibility of materials flowing the wrong direction in a water line. 
The most common backflow preventer device is a Reduced Pressure Zone (RPZ). This device is designed to allow the system connected to it to vent to the atmosphere if the water distribution system loses pressure. This ensures there will be no backflow into the public water supply thus protecting the water supply from contamination. RPZ backflow preventers are installed on: in-ground sprinkling systems, fire protection systems connected to the water supply, commercial or manufacturing sites that have water connected to any process.