The Ministry of the Environment Ontario has amended Regulation 170/03 effective June 5, 2006.
As a regulation made under the Safe Drinking Water Act, 2002, Regulation 170 sets water testing and treatment standards for municipal and private systems that provide water to year-round residences and those systems that serve designated facilities such as schools, day care services, health centres and social care facilities. Water testing and operating requirements have been amended to facilitate a clearer set of guidelines, to provide more treatment options, and reduce costs for smaller systems.

Implemented in June 2003, the original version of Reg. 170 was severely and widely criticized as being too stringent and financially onerous. In October 2004, the AMO Regulation 170 Task Force released 23 recommendations on how to improve the system, which are available on the Municom website. Ministry of the Environment (MOE) staff worked very closely with AMO to ensure the new Regulation was both workable and affordable for both the non-municipal and municipal operators.  

In May 2005, the government announced its intention to make public health units responsible for ensuring facilities such as churches, community halls, bed and breakfasts and tourist outfitters have safe drinking water. On June 3, 2005, systems serving non-residential and seasonal residential uses became subject to Regulation 252/05. MOE announced the move to the new risk-based Reg. 170 on June 7, 2006.  
Highlights of interest to municipalities:


  • Clearer and less frequent microbiological testing requirements;
  • Less frequent testing for chemical parameters;
  • Clearer definitions of terms such as weekly, bi-weekly and monthly.
Corrective Action
  • Clearer and updated corrective actions and chlorine residual levels.
Operational Requirements
  • Enable point of entry treatment to be used as an alternative to centralized treatment and distribution of water.
  • Flexibility for performing operational checks within all systems, except large municipal residential systems.
AMO will continue to monitor developments in water policy to ensure the high quality of municipal drinking water is maintained without any additional burden to the property tax base.