Recommendations for reopening building water supply systems
Building owners and operators need to prepare in advance
Use our reopening recommendations to safely re-open your building’s hot and cold water supply following a long term shut down.
How building closures can affect water quality
Serious problems can happen when water pipes in a closed building are not maintained or routinely flushed.
Stagnant water in the building’s pipes, equipment and water storage tanks can cause building plumbing issues and concerns with water quality and water appearance.
It can also increase potential adverse effects or health risks such as:
- An unpleasant taste and odour.
- Water discoloration.
- Growth of disease-causing bacteria such as Legionella.
- Dissolved metals (such as lead, copper and iron) in the water due to corroding pipes.
- Disinfection by products: chemicals or other substances that can form when natural organic matter in the water reacts to a disinfectant (like chlorine).
In Peel, the Region is responsible for supplying clean, safe drinking water to each property.
As a building owner or operator, you are responsible for maintaining the safe water supply from your property line to and within your building*. You are also responsible for protecting the health of those who use your building’s water.
*The information the link refers to is homeowner’s responsibilities for their private side pipes. This information applies to all private side pipes both residential and business.
Begin by reviewing your water management plan
Before taking any action, review your existing water management plan and a sketch of the entire building and property.
- Identify areas that include all treatment and process equipment such as pumps, valves, and tanks.
- List all inlets, outlets, and fixtures such as taps, drinking water fountains and showers.
- Include any connected food units like fridge water dispensers, ice or coffee makers and dishwashers.
- Run any water-using fixtures like dishwashers and washing machines through an empty cycle. Stale water in the water lines of these fixtures can cause laundry to discolor and smell.
Flushing the entire system
After months of inactivity, the building plumbing must be flushed (by opening taps and equipment) to move the stagnant water out. We also recommend cleaning all taps, devices and fixtures.
Staff must wear appropriate personal protective equipment such as gloves, a mask and eye coverings while flushing the system.
If your building is large, perform the required water testing for large buildings after the pipes are flushed to confirm water safety and quality.
Flush your cold-water supply first before flushing hot water taps.
Water supply system flushing instructions
Flushing conditions will vary based on your building’s piping configuration and size.
- Bypass any inline water filters before starting the flush.
- Start by opening taps where the water enters the building. Open all the taps as you work your way to the farthest water outlet.
- Run the water until it’s consistently cold and you can smell chlorine. Municipal water in Peel has a mild chlorine smell.
- This flushing should be rigorous. Be sure to open the taps fully, removing any faucet aerators, screens, filters or shower heads. Be aware that removing these items might cause greater spray.
- The hot water tank setting should be kept above 60oC (140oF). This will ensure a temperature over 50oC (122oF) throughout the system.
- Be sure to flush the hot water tank fully to replace all the water. Consider draining the tank (while being cautious that this could stir up sediment or cause drain valve issues).
- Flush the hot water system piping from closest valve to furthest valve from the tank.
- Inspect, clean, disinfect and rinse all outlets, aerators, screens and all other water source devices and equipment.
- After flushing, replace any water filters already in place, including conditioning agents in water softeners.
If water system shocking is necessary, it should be conducted by a qualified water treatment professional.
You may need shock chlorination if you have a large system that:
- Has remote branches and storage tanks.
- Still has issues after flushing.
- Serves vulnerable populations or has a history of pathogen problems. A pathogen is an organism that causes disease (like viruses, bacteria, fungus, and parasites)
Water testing for small buildings
If your building is small, the water should be consistently cold and have a mild smell of chlorine.
If your building is large or serving vulnerable populations, we highly recommend water testing.
Testing for chlorine residual should be performed by a qualified person using appropriate and calibrated testing equipment.
Testing for microbial parameters should be carried out by an accredited laboratory for a building or facility that is:
- Serves vulnerable populations.
- Has a history of contamination (i.e., Legionella, which is often related to water in heating, cooling, and ventilation systems).
More information on opening water supply systems
This guidance is meant to give simple step-by-step instructions for safely reopening a building’s water supply system.
For more detailed information, review the Ontario Guide for maintaining building plumbing after extended vacancy or Canadian Water and Wastewater Association guidance documents.
The Region of Peel continuously monitors the water quality of its municipal drinking water supplies. To learn more about how we test and treat water in Peel, read our water and wastewater quality reports.
If you have a specific question about water quality in Peel, email the Region of Peel Water Quality and Compliance department.
For guidance on water testing in private buildings, call Peel Public Health at 905-799-7700.