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Middlesex-London Health Unit

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Municipal Water

Middlesex-London has many large drinking water systems that supply water to its residents. These systems provide municipal water, which is also known as city water. Operators of these municipal water systems are highly trained in terms of checking the safety of the drinking water and carrying out regular water quality testing as required by the Ontario Drinking Water Systems Regulation (O. Reg. 170/03).1

Public Health Inspectors at the Middlesex-London Health Unit are not directly involved with the day to day operations of municipal water systems. However, Public Health Inspectors do work closely with operators of these systems, as well as a number of other agencies, to make sure only the safest water is provided to the public.

Other agencies involved in providing safe municipal water to the public include:

Municipal Water Testing

Regular bacteria and chemical testing is carried out on drinking water by all municipal water systems operators to make sure the Ontario Drinking Water Quality Standards (O. Reg. 169/03)2 are met.   

If a water sample test shows bad results, the Middlesex-London Health Unit will do a risk assessment and decide which corrective actions are needed. The Health Unit will provide detailed directions to the municipal water system operator. Corrective actions could range from simply flushing the water system and re-sampling the water to issuing a boil water or drinking water advisory right away.

Additional Information

For more information about the day to day operations of your municipal water system, please contact:

  • The City of London Water Division - 519-661-4739
  • Your local municipality, or
  • The Ontario Ministry of the Environment, Conservation and Parks office - 519-873-5000

To speak to a Public Health Inspector on the Environmental Health Team about drinking water or drinking water quality, please call: 

  • 519-663-5317
Date of creation: December 14, 2012
Last modified on: January 24, 2022


1Ontario. Ministry of the Attorney General. (2003). Safe Drinking Water Act, 2002. Ontario Regulation 170/03 Drinking Water Systems. Retrieved from
2Ontario. Ministry of the Attorney General. (2003). Safe Drinking Water Act, 2002. Ontario Regulation 169/03 Ontario Drinking Water Quality Standards. Retrieved from