Ontario Regulated Lead Testing Program

Learn more about the City’s Corrosion Control Plan and read the latest annual update on the City of Toronto’s Lead in Drinking Water Mitigation Strategy.

About the Ontario Regulated Lead Testing Program

The Provincial Government implemented a Regulated Lead Testing Program in 2007. Under this program, Toronto Water is required to collect, analyze and submit the results of water samples taken in areas suspected of having lead water service pipes. Under the original program, twice a year, Toronto Water collected and reported the results of samples from:

100 residential water service connections
20 connections from within the distribution system
10 non-residential water service connections

City of Toronto Corrosion Control Program

In 2009, Toronto Water began developing a Corrosion Control Program as mandated and approved by the Province under the Safe Drinking Water Act.

During the design and implementation of corrosion control (2009-2017), the Province required the City to collect and analyse 20 samples from the water distribution system twice a year. Results are shown below.

In 2014, the City implemented corrosion control by adding phosphate to the drinking water treatment process at the four water treatment plants. Phosphate forms a protective coating inside all pipes and household plumbing fixtures, which helps to reduce the potential for lead to enter tap water. Ongoing results indicate a reduction in lead levels.

In March 2017, Toronto Water resumed the regulated sampling program, which includes taking samples throughout the year from at least:

55 residential and non-residential tap locations
10 distribution system locations

These results are submitted to the Ontario Ministry of the Environment, Conservation and Parks (MECP). Learn more about the City’s Corrosion Control Plan and read the latest annual update on the City of Toronto’s Lead in Drinking Water Mitigation Strategy.

*In 2020, due to COVID-19 and limited access to plumbing samples, the MECP granted Toronto Water with regulatory relief for the collection of regulatory samples. Toronto Water collected a limited number of plumbing samples in 2020, reflected in the chart below.

Regulated Test Results

Round 23 (January - December 2021)

Period

Locations

# of Locations

Lead Result
– ug/L

Max.	Min.	Avg

% of Samples
> 10 ug/L

Round 23 January – December 2021

Residential and Non-Residential Taps

5.15 <0.05 0.66

Round 23 January – December 2021

Distribution System

0.26 <0.05 0.08

Round 22 (January - December 2020)

Period	Locations	# of Locations	Lead Result – ug/L	% of Samples > 10 ug/L
Max.	Min.	Avg.
Round 22 January – December 2020	Residential and Non-Residential Taps	13	5.2	<0.05	0.66	0
Distribution System	7	0.35	<0.05	0.10	0

Period

Locations

# of
Locations

Lead Result
– ug/L

% of Samples
> 10 ug/L

Max.

Min.

Avg.

Round 22

January
–
December

2020

Residential and Non-Residential Taps

5.2

<0.05

0.66

Distribution System

0.35

<0.05

0.10

Round 21 (January - December 2019)

Period	Locations	# of Locations	Lead Result – ug/L	% of Samples > 10 ug/L
Max.	Min.	Avg.
Round 21 January – December 2019	Residential and Non-Residential Taps	58	9.4	<0.05	0.50	0
Distribution System	20	1.2	<0.05	0.16	0

Period

Locations

# of
Locations

Lead Result
– ug/L

% of Samples
> 10 ug/L

Max.

Min.

Avg.

Round 21

January
–
December

2019

Residential and Non-Residential Taps

9.4

<0.05

0.50

Distribution System

1.2

<0.05

0.16

Round 20 (January - December 2018)

Period	Locations	# of Locations	Lead Result – ug/L	% of Samples > 10 ug/L
Max.	Min.	Avg.
Round 20 January – December 2018	Residential and Non-Residential Taps	58	35.7	<0.05	1.2	1.7
Distribution System	21	0.93	<0.05	0.14	0

Period

Locations

# of
Locations

Lead Result
– ug/L

% of Samples
> 10 ug/L

Max.

Min.

Avg.

Round 20

January
–
December 2018

Residential and Non-Residential Taps

35.7

<0.05

1.2

1.7

Distribution System

0.93

<0.05

0.14

Round 19 (January - December 2017)

Period	Locations	# of Locations	Lead Result – ug/L	% of Samples > 10 ug/L
Max.	Min.	Avg.
Round 19 January – December 2017	Residential and Non-Residential Taps	55	73.2	<0.05	2.8	1.8
Distribution System	10	0.85	<0.05	0.28	0

Period

Locations

# of
Locations

Lead Result
– ug/L

% of Samples
> 10 ug/L

Max.

Min.

Avg.

Round 19

January
–
December 2017

Residential and Non-Residential Taps

73.2

<0.05

2.8

1.8

Distribution System

0.85

<0.05

0.28

Rounds 17-18 (December 2015-October 2016)

Period	Locations	# of Locations	Lead Result – ug/L			% of Samples > 10 ug/L
Period	Locations	# of Locations	Max.	Min.	Avg.	% of Samples > 10 ug/L
Round 18 June 2016 – October 2016	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	1.2	<0.05	0.3	0

Round 17 December 2015 – April 2016	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	0.65	0.06	0.2	0

Rounds 13-16 (December 2013-October 2015)

Period	Locations	# of Locations	Lead Result – ug/L			% of Samples > 10 ug/L
Period	Locations	# of Locations	Max.	Min.	Avg.	% of Samples > 10 ug/L
Round 16 June 2015 – October 2015	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	1.2	0.06	0.3	0

Round 15 December 2014 – April 2015	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	104	0	7.9	3

Round 14 June 2014 – October 2014	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	0.96	<0.05	0.3	0

Round 13 December 2013 – April 2014	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	1.9	0.07	0.6	0

Rounds 9-12 (December 2011-October 2013)

Period	Locations	# of Locations	Lead Result – ug/L			% of Samples > 10 ug/L
Period	Locations	# of Locations	Max.	Min.	Avg.	% of Samples > 10 ug/L
Round 12 June 2013 – October 2013	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	<0.5	<0.5	<0.5	0

Round 11 December 2012 – April 2013	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	1	<0.5	0.3	0

Round 10 June 2012 – October 2012	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	8	<0.5	0.9	0

Round 9 December 2011 – April 2012	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	2	<0.51	0.6	0

Rounds 5-8 (December 2009-October 2011)

Period	Locations	# of Locations	Lead Result – ug/L			% of Samples > 10 ug/L
Period	Locations	# of Locations	Max.	Min.	Avg.	% of Samples > 10 ug/L
Round 8 June 2011 – October 2011	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	4	<0.51	1.1	0

Round 7 December 2010 – April 2011	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	0.7	<0.51	0.1	0

Round 6 June 2010 – October 2010	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	2	<0.51	0.5	0

Round 5 December 2009 – April 2010	Private Residential Plumbing
	Private Residential Plumbing – (Lead > 11 ug/L)
	Non-Private Residential Plumbing
	Distribution System	20	5	<0.51	0.7	0

Rounds 1-4 (December 2007-October 2009)

Period	Locations	# of Locations	Lead Result – ug/L			% of Samples > 10 ug/L
Period	Locations	# of Locations	Max.	Min.	Avg.	% of Samples > 10 ug/L
Round 4 June 2009 – October 2009	Private Residential Plumbing	100	22	<0.51	6.1	18
	Private Residential Plumbing – (Lead > 11 ug/L)	18	22	11	16.9	–
	Non-Private Residential Plumbing	10	15	1.0	3.3	1
	Distribution System	21	4	0	1.0	0

Round 3 December 2008 – April 2009	Private Residential Plumbing	102	38	<0.51	3.9	7
	Private Residential Plumbing – (Lead > 11 ug/L)	7	38	11	16.9	–
	Non-Private Residential Plumbing	10	4	<0.51	0.7	0
	Distribution System	21	4	<0.51	0.8	0

Round 2 June 2008 – October 2008	Private Residential Plumbing	100	82	<0.51	11.9	52
	Private Residential Plumbing – (Lead > 11 ug/L)	52	82	11	18.6	–
	Non-Private Residential Plumbing	10	6	<0.51	0.8	0
	Distribution System	21	5	<0.51	0.6	0

Round 1 December 2007 – April 2008	Private Residential Plumbing	100	14	<0.51	3.8	6
	Private Residential Plumbing – (Lead > 11 ug/L)	6	14	11	12.8	–
	Non-Private Residential Plumbing	10	2	<0.51	0.6	0
	Distribution System	20	6	<0.51	0.7	0

Ontario Drinking Water Quality Standard for Lead = 10 ug/L (micrograms per litre)

Results with “<” means less than the Method Detection Limit