Water Quality Data and Education

Our qualified staff of water utility professionals are dedicated to providing our customers with the best quality drinking water possible and we continue to meet or produce better quality water than State and Federal regulations require. We operate 7 days a week, 365 days a year and conduct approximately 15,000 tests per month on our water for more than 100 contaminants.

Our qualified staff of water utility professionals are dedicated to providing our customers with the best quality drinking water possible and we continue to meet or produce better quality water than State and Federal regulations require.

Ensuring water safety

Removing contamination

The Ann Arbor Drinking Water Treatment Plant is designed to remove contamination to produce high quality drinking water. We have multiple barriers of defense for each type of contamination that might come from our source water:

lime softening to remove minerals (to protect your appliances);
disinfect with ozone to destroy bacteria and other microorganisms;
filter through granular activated carbon and sand to remove particles, PFAS, and other organic contaminants;
disinfect again with UV light;
use monochloramine disinfectant to keep the water safe from microorganisms as it travels to your home.

We conduct 175,000 tests on our water per year and provide data to you on our website as well as to the state of Michigan to optimize the process and prove the water treatment process is reliable and produces high quality drinking water that is safe to drink.

As the water travels to your house, one way we ensure no contamination can enter the system is by keeping it pressurized, so if a leak occurs water rushes out and blocks contamination from entering. During the winter, we see the most main breaks because as the ground freezes and thaws, so does any water trapped in the soil. Water molecules in ice are arranged in a structure that takes up more space than liquid water, forcing the ground to expand. While the water mains are buried below the frost line underground, the extra force from the expanded ground above is enough to cause leaks. Furthermore, the pipes themselves can expand and contract as temperatures change causing more stress on our aging infrastructure.

Testing for contaminants

Our monthly water quality dashboard shows the most recent month of available results. Testing for PFAS and 1,4-dioxane is completed by a subcontract lab with specialized instrumentation and experienced staff, so results can take a month or more to be provided to us. City of Ann Arbor uses multiple lines of defense against each type of contaminant, and we monitor each treatment step closely using both real-time performance indicators and longer term testing of specific contaminants. This strategy allows us to keep your water safe from contaminants that can be analyzed quickly as well as those that require more time and specialized instrumentation.

If you have any specific concerns or water quality questions, we look forward to answering them. Staff can be reached at 734.994.2840 or via email.

Ann Arbor Water and Harmful Algal Blooms (HABs)

Did you know that Ann Arbor Water keeps a close watch on the Huron River for harmful algal blooms (HABs) and their toxins? These naturally occurring blooms—caused by certain types of bacteria called cyanobacteria—can sometimes produce toxins, but rest assured: Ann Arbor’s water is safe to drink.

Our water treatment plant tests for over 200 potential contaminants and runs more than 175,000 water quality tests every year. Our Annual Water Quality Report shows only a subset of these analyses because it does not include contaminants that we do not detect. One of these classes of contaminants that was not detected this year in treated drinking water is toxins from Harmful Algal Blooms.

We use advanced treatment methods that effectively remove toxins—without needing any changes if a bloom were to occur. We also monitor upstream activity and follow a detailed HAB response plan to stay ahead of any issues.

There are currently no federal regulations for algal toxins, but the Environmental Protection Agency (EPA) offers health guidelines—and Ann Arbor uses even more strict safety limits for all residents. The toxins we test for are consistently undetected or well below those limits.

Ann Arbor’s advisory levels for all consumers are 0.3 parts per billion (ppb) microcystins and 0.7 ppb for cylindrospermopsin. Over the past four years in the untreated source water from Barton Pond, the cyanotoxins anatoxin-a, cylindrospermopsin, and nodularin were not detected, and total microcystin concentrations were below <0.3 ppb.

Reporting a concern or problem

To report a drinking water quality concern or notice low/no water pressure, please use the A2 Fix It app on your phone or visit the A2 Fix It page to make a service request.

For sanitary sewer back-ups, possible sewage leaks (if you smell sewage for example), plugged storm drains, or basement flooding please contact us by phone. During normal business hours: Monday – Friday, 7:30 a.m. to 5:30 p.m., please call 734.794.6320. After hours, evenings, weekends and holidays, please call the Water Treatment Plant at 734.794.6426.