Drinking Water

Re-opening a building after an extended closure due to the pandemic.

Drinking Water Sources

Buildings that have been closed or dormant for 4 weeks or more require steps to be taken before re-opening to ensure water is safe for use and/or consumption.

This includes dumping, flushing, servicing, and cleaning of any water system (drinking water treatment, distribution, storage and plumbing).

If water has been sitting in the pipes for a few hours, be sure to run cold water for at least 5 minutes before using. Or, flush the toilet, shower, or do laundry to clear the standing water from your pipes, then run cold water for 1 to 2 minutes before using.

Consideration should be given to all water systems and especially to those systems of higher risk such as residential systems, restaurants, hotels, motels, cottages, schools and child care centres, gyms and any system with showers. 

Vulnerable components of systems including filters, tanks, faucet filters, taps, showers, ice machines, fountains, food preparation, or other decorative water features, eyewash stations, humidifiers and other systems involving evaporative cooling (e.g. certain HVAC), hot tubs, pools, water features that generate aerosols (fountains, spas, etc.), parts of the water system that are used by children, and, components of the water system used by elderly people and susceptible people. 

Water left in the system before the closure will be old/stagnant, likely elevated in corrosion products (including lead and copper), low in disinfectant where it is used, or elevated in disinfection by-products where disinfection is used. Plumbing pathogens will have had the opportunity to proliferate in the bulk water and biofilm. 

The Canadian Water and Wastewater Association (CWWA) has developed the following documents to help support building owners during this process.

Drinking water comes from many different sources such as lakes, rivers, and shallow, dug, or drilled wells. We use this water every day for drinking, brushing our teeth, washing fruits and vegetables, bathing, and cleaning dishes. Drinking water in Ontario must meet specific standards set by Health Canada. Water test results can be compared to the Guidelines for Canadian Drinking Water Quality.

Our Health Unit works with different community partners to make sure everyone has access to clean drinking water. These partners include:

  • Working with operators of municipal water systems Ontario Regulation 170/03.
  • Working with operators of small drinking water systems Ontario Regulation 319/08.
  • Issuing boil water or drinking water advisories when drinking water has been contaminated or there’s a chance for contamination.
  • Helping home owners on a private well test and understand their results.
  • For addition information regarding water testing visit the Public Health Ontario Website.

Private Well Water

The Windsor-Essex County Health Unit reminds its residents that if you are drinking water from a private well on your property, you can test your well water for free!

Year-round well water testing is free of charge for private residential use. Water is tested for total coliform and E. coli bacteria.


Listeria is a bacteria that can cause a rare but serious illness called listeriosis. Those who are pregnant, the elderly, and those with a weakened immune system have a higher risk of becoming seriously ill.

Blue-Green Algae Bloom

Blue-green algae are microscopic bacteria that occur naturally in fresh water lakes. In warm weather, with the right nutrients and low wind, they can form a large mass called a bloom. Residents and visitors are urged to take a cautious approach, monitor the situation, and protect themselves from potential health risks.

Cryptosporidiosis (Crypto)

Cryptosporidiosis (crypto) is an infection caused by a group of parasites (germs), called cryptosporidium. Most infections occur in a person’s stomach and intestines (gastrointestinal tract). Infections can occur in other parts of the body, such as the lungs. These germs can infect humans, cattle, and other animals.


Campylobacter enteritis is an infection caused by a group of bacteria.  These germs live mostly in the intestines of animals, including poultry, cattle, rodents, and household pets.


Amebiasis is an infection caused by a parasite, called Entamoeba histolytica. It lives in the feces (poop) of a person. Most infections occur in a person’s stomach and intestines (gastrointestinal tract). In some people, the disease may occur in the liver, lungs, skin, and other parts of the body.

E. Coli

Escherichia coli, also called E. coli, are bacteria that are often found in the intestines of people and animals. There are different types of E. coli. Some types of E. coli are not harmful, but others like E. coli O157:H7, can make some people very sick. Usually illness is caused by eating contaminated food or water, having contact with someone who is sick with the bacteria, or animals that carry it.