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Water Testing Results

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Drinking Water Quality Reports

The Safe Drinking Water Act (SDWA) is the federal law that protects public drinking water supplies throughout the nation. Under the SDWA, the US EPA sets standards for particular contaminants in drinking water. Water supply systems must test for these contaminants and, if necessary, the water is treated to reduce contaminants to the maximum contaminant levels (MCLs) set for each contaminant. 

Each year water supply systems test these water quality parameters, at different intervals, established by the Illinois EPA and US EPA to protect public health. Along with every public water supply in the United States, the City of Highland Park publishes an annual report, the Consumer Confidence Report (CCR).  Read the current CCR here.

The annual CCR only details the detected results of water quality monitoring over the previous year.  Any contaminant that was not detected is not added to the CCR but is submitted to the Illinois EPA. All water quality monitoring results can be found on the IEPA's Drinking Water Watch website.  Any contaminant that the City of Highland Park tested for, and those results, can be found there.

Below is a list of contaminants that The City of Highland Park monitors for and the frequency at which it is done. To read previous CCRs please visit our archived CCRs here.

Continuously monitored (at multiple locations): 

  • Chlorine Residual on Finished Water – Chlorine guards against microbial contamination between the Water Plant and the consumer.
  • Turbidity on Finished Water – Turbidity is a measurement of clarity, a key measurement of treatment performance.
  • ORP on Raw Water – ORP is a common measurement of water quality and is used to detect any changes needed in the dosing of disinfectant.


Tested Daily: 

  • Coliform on Raw Water – Checked to see microbial contamination of water before treatment.
  • Coliform on Finished Water – Checked to verify bacteriological quality of water after treatment.
  • pH & Temperature on Raw Water - Checked to optimize treatment chemical dosing.
  • pH on Finished Water – Checked to verify treated water quality.
  • Turbidity on Raw Water – Checks are performed every 4 hours to measure the clarity of water before treatment.
  • Turbidity and Chlorine Residual on Finished Water – Checks are performed every 4 hours to verify water quality after treatment.
  • Fluoride on Finished Water – Fluoride is added to prevent tooth decay.  The Illinois Department of Public Health, Division of Oral Health’s acceptable range is 0.60 – 0.80 ppm.
  • Orthophosphate on Finished Water – Orthophosphate is added to inhibit corrosion. Illinois EPA requires a concentration greater than 0.40 ppm.


Tested Monthly:

  • Revised Total Coliform Rule (rTCR) - 30 samples are collected throughout the City’s water distribution system and tested for microbial contamination, Chlorine Residual, and Turbidity.
  • Total Organic Carbon (TOC) and Alkalinity on Raw Water – Checked to measure water quality before treatment.
  • TOC on Finished Water – Verifies water quality after treatment.


 Tested Quarterly:

 Tested Annually:

  • Chemical Contaminants Rule – over 65 contaminants in three contaminant groups listed below:
    • Inorganic Contaminants (IOC) – 1 Finished Water sample tested for metals and salts including Nitrate and Nitrite
    • Synthetic Organic Contaminants (SOC) – 1 Finished Water Sample tested for synthetic chemical byproducts of industrial processes and petroleum production, including pesticides and herbicides
    • Volatile Organic Contaminants (VOC) – 1 Finished Water Sample tested for volatile chemical byproducts of industrial processes and petroleum production
  • Lead and Copper Rule - 30 Lead and Copper samples collected throughout the City’s water distribution system to verify optimal corrosion control treatment.  For more information on lead, please visit our lead information page.

 Tested Every 9 Years:

Other Frequencies:

  • Unregulated Contaminant Rules (UCMR) – samples collected every 5 years and tested for up to 30 contaminants that may be present in drinking water but do not yet have health based standards set under the Safe Drinking Water Act
  • Long Term Enhanced Surface Water Treatment Rule (LT2ESWTR) – 1 Raw Water sample collected a month for a period of 24 months starting in October 2016 and tested for Cryptosporidium, E. coli, and turbidity

For More Information
For more information about the Drinking Water Quality Reports, you are encouraged to contact the Water Plant at waterplant@cityhpil.com or 847.433.4355.