Regulation - LGIC

Proposal to adopt a more stringent Ontario Drinking-Water Quality Standard (ODWQS)

Regulation Number(s):
O.Regulation 169/03
Instrument Type:
Regulation - LGIC
Bill or Act:
Safe Drinking Water Act, 2002
Summary of Proposal:
The Advisory Council on Drinking Water Quality and Testing Standards recommended that the ministry adopt a more stringent ODWQS of 0.08 mg/L (80 ug/L) for total THMs in drinking water phased-in over a period of two years as follows:

- Treatment plants undergoing significant expansions or significant upgrades should be designed to, at minimum, meet the new total THMs standard without compromising disinfection effectiveness.

- All other treatment plants should, at minimum, meet the new total THMs standard, without compromising disinfection effectiveness, within a period of two years from the date that the standard is promulgated.

The lower value recommended is supported by the stakeholder comment on the EBR. A recent review of treatment plant performance determined that 0.08 mg/L (80 ug/L) for total THMs can be, or has been, already achieved by most of Ontario's treatment plants.

Further Information:
Proposal Number:
Posting Date:
April 12, 2006
Comments Due Date:
May 7, 2006
Contact Address:
Satish Deshpande,
Team Leader,
Drinking Water Standards
Standards Development Branch/ Water Standards Section
40 St. Clair Avenue W.,
7th Floor,
Toronto, Ontario, M4V 1M2
PHONE: (416) 327-4689
FAX: (416) 327-9091