The Evanston Water Quality Laboratory is certified by the Illinois Department of Public Health (IDPH) to analyze water for bacteriological contamination as well as other indicators of water quality such as turbidity (measure of particles the water) and residual chlorine concentration. IDPH inspectors audit the laboratory every two years. The audit consists of an onsite evaluation in which procedures, records, and equipment are inspected. Over 200 different criteria must be met in order to be in perfect compliance with Zero Deviations. Evanston's water quality lab has received the highest score of Zero Deviations five times in a row (most recent inspection in April 2015).
A membrane filter technique is used to test the water for the presence of total coliform using EC broth verification. Testing is done daily of both the raw (untreated) and finished (treated) waters. In addition, over 80 tests are conducted on water samples collected from the Evanston distribution system each month. Evanston also performs the bacteriological analysis of water samples collected from the Village of Skokie and submits the results to the Illinois Environmental Protection Agency for compliance with Safe Drinking Water Regulations. In total, Evanston's water quality lab performs over 37,000 individual tests on water samples throughout the year, an average of over 100 tests per day.
The Water Quality Laboratory is also certified by the Illinois Environmental Protection Agency (IEPA) for the monitoring of pH and fluoride. The IEPA certifies laboratories in the State of Illinois for the analysis of chemical substances while the Illinois Department of Public Health certifies labs for bacteriological parameters. Laboratories must meet stringent criteria and staff is thoroughly reviewed on site every three years to maintain certification.
The lab is staffed by a full time chemist and microbiologist. In addition, water plant operators, working around the clock, are also certified to perform bacteriological analysis as well as trained to monitor turbidity levels (the level of suspended solids in the water), chlorine levels, and all chemical feed rates to ensure high quality production 24 hours a day, 365 days a year.
Evanston's water is sampled and tested for the content of a number of substances that entail highly complicated and specialized analytical procedures. These types of tests, which require equipment and staffing that are not feasible for the City to maintain, are performed by the IEPA Community Lab. This program provides laboratory services for community water supplies on a fee basis. The kind of testing that is performed by the Community Lab Program include disinfection by-products, volatile organic chemicals, synthetic organic chemicals, haloacetic acids, lead, copper, total organic carbon, and any other substance in which equipment and resources are not available in-house.