A potential risk of water contamination has the city of Onalaska doing mandated check-ups.
The city will be doing residential and commercial check-ups on all water hook-ups.
The Utility Department will be looking for any places water can back flow into the city's water system.
"Quite often they look at your toilet to see how that is operating and functioning. They look a lot of times on the outside of your house for a hose bib where the house is connected to make sure you have a vacuum breaker on that," said City Engineer Jarrod Holter.
The city should be contacting residents to set up an appointment for inspection in the near future.