Water mains are underground pipes that carry water from pumping stations to your street, and service pipes connected to your house. The City of Cambridge cleans water mains on a regular basis to remove accumulated material and maintain drinking water quality.
The annual Water Main Cleaning Program consists of a combination of water main swabbing and flushing. No chemical cleaning products are used in this process, and minimal water service interruptions are experienced by customers.
In advance of work being done, blue card notices will be hand delivered to customers who are in the immediate area of the cleaning activities. Customers outside of these areas may also experience discoloured water. This is a temporary condition, and should clear within a few hours of daily work concluding. If you have any questions, call Service Cambridge at 519-623-1340.
I received a door hanger notice. What should I do?
Before Flushing
Since water cannot be used during the cleaning process, you should:
- Fill a clean container with tap water for drinking and cooking.
- Complete dishwashing, clothes washing, and other activities prior to the cleaning start time indicated on the door hanger notice you receive.
- Turn off the main water supply by using the shut off valve (usually located at your water meter).
- If shutting the valve is impossible and you have an automatic water filtration system (ie. water softener), put the system on bypass to prevent it from using water.
During Flushing
- Do not use any water or flush your toilet to avoid drawing discoloured water into your home’s pipes and causing internal plumbing issues.
After Flushing
- Use a cold, hard (unsoftened) water tap closest to your water meter, like a basement laundry tub, to flush your water service.
- Some customers may experience temporary discolouration of their water, which should not be consumed.
- If you notice discoloured water, run the cold, hard (unsoftened) water tap closest to your water meter for 10 minutes at medium speed, pencil size stream.
- If the water remains discoloured after 10 minutes of running your tap, turn off the tap, wait 60 minutes and repeat the 10-minute flushing process again.
- If your water does not clear after 2 hours, please contact Service Cambridge at 519-623-1340 for assistance.
Frequently asked questions
How does the City notify customers affected by the program?
We use a number of methods to inform customers of planned water main cleaning and possible discoloured water caused by the program. Notification is done by the following methods:
- Door hanger notifications are placed on customer’s door notifying of cleaning day and time
- Information shared through the City’s official social media accounts (Instagram, Facebook or Blusky)
What is the cleaning process?
Water main flushing is done by forcing water through water mains at high speed and discharging it through a fire hydrant. The fast-moving water flow scours and cleans out mineral deposits and sediment that may have built up over time.
Water main swabbing entails inserting a soft material bullet-shaped device, called a swab, into the water main through a fire hydrant. The diameter is slightly larger than the water main and the swab is pushed through the water main by water pressure. As it passes through the water main, the swab scours the inside of the pipe and removed any built-up material.
Will water main cleaning impact my water service?
Your water service will not be turned off but we advise that you do not use water during the cleaning process to avoid drawing discoloured water into your home’s pipes.
Is flushing my pipes to remove discoloured water expensive for me?
At the 2026 water rates ($2.82 per m³) a customer in Cambridge pays approximately 4 cents for every minute that a tap runs. The recommended 10-minute flushing process will cost approximately 39 cents.
