Environmental Services

Alberta is embarking on a comprehensive program of testing for lead in drinking water “at the tap”. The protocol for collecting samples generally follows the Health Canada (HC) Guidance document published Mar. 2019[1], however, there are some important differences.

It is important to know that Federal sites, airports, military bases, etc. follow the HC guidance while all other samples in Alberta follow the Alberta Environment and Parks (AEP) Guidance[2]. British Columbia does not yet have drinking water-specific protocols, but BC customers may request either or opt for sampling practices typical for non-drinking water samples.

The HC and AEP Maximum Acceptable Concentration (MAC) for lead in drinking water is 5 ug/L. BC remains at 10 ug/L, but it is anticipated that the provincial regulators will adopt the lower standard at some point.

Sources of Lead in Drinking Water

In general, source water and water mains are lead free. Supply pipes from the water mains may contain lead. Potential sources of lead within a building’s distribution system include lead service lines (LSLs), solder, brass fittings and fixtures.

Alberta Protocols

Detailed information on lead assessment in Alberta drinking water systems can be found in: AEP Guidance Document for Managing Lead in Municipal Drinking Water Systems in Alberta: Phase 1 tools for utilities to plan, assess and implement lead management plans for 2020-2024.

Table 1 describes the various types of samples and specific sampling practices to monitor lead in municipal drinking water systems in Alberta. Note: As can be seen, the vast majority of sample volumes are 1L. The 1L volume is a requirement. Smaller bottles cannot be substituted where 1L samples are specified.

Health Canada Protocols

Detailed information on lead assessment in Federal drinking water systems can be found in: Guidelines for Canadian Water Quality – Guideline Technical Document – Lead March 2019.

Table 2 describes the various types of samples and specific sampling practices used to assess lead in drinking water at federally governed sites (Airports, Canadian Forces Bases, etc.)

Table 1: Alberta Drinking Water Protocols

SAMPLING LOCATION SAMPLING PROTOCOL COMMENTS
Residential Buildings Random Daytime Sampling (RDT) A 1-L sample is collected randomly during the day in each of the locations chosen to be surveyed. Samples are collected without prior flushing. No stagnation period is prescribed in order to better reflect customer use.
This approach represents a worst case scenario in terms of consumer exposure and is usually the first course of action.
30-minute Stagnation (30MS) 30MS is used for system assessment, investigating the cause of exceedances and identifying appropriate mitigation measures. This method enables detection of the proportion of problem properties, is representative of household installation and water properties and provides an accurate repeatable value for average weekly lead concentration. However, it underestimates the highest levels of lead at the tap and is inconvenient due to the length of time the sampler spends in the residence and does not represent customer behavior.
After flushing the system for 2-5 min., no water is used for 30 min. after which 2 x 1L samples are collected sequentially.
30-minute Stagnation (30MS-XL) This protocol is used for the same reasons and using the same protocol as 30MS noted above, except that sufficient samples are collected to include the entire volume within the system to the main.
Profile (sequential) Sampling This approach is used to assess responsibility (source of lead contamination). If a LSL is present, the cumulative volume to collect water that was stagnant in the household plumbing and service lines is site dependent.
Collect consecutive samples (typically four or more 1-L samples) at the tap after stagnation. The volume collected (number of consecutive 1-L samples) needs to cover the piping volume from the tap to the main. Optionally, sample volumes of 125 mL or 250 mL may be used at the beginning of the sequence (filled first) to indicate lead contribution from the faucet and immediate plumbing, followed by 1-L volumes.
Flushed Sampling This protocol is used to determine the lead content in water from the main (source water characterization).
A 1-L sample is taken after the supply has been run for a period long enough to ensure that water from the main is being sampled. The duration of flushing is dependent on the plumbing configuration, but 5 minutes of flushing at a moderate flow rate is commonly used.
Large residential buildings Random Daytime Sampling (RDT) Sampling priority should be given to locations suspected or known to have LSLs or internal lead plumbing.
Collecting two 125-mL samples to capture typical exposures. (Note: Collection of samples representing stagnation are nearly impossible to coordinate because of the number of occupants in the building)
Profile, Flushed sampling Described, above, used as required.

 

Table 2: Health Canada Drinking Water Sampling Protocols

SAMPLING LOCATION SAMPLING PROTOCOL COMMENTS
Residential Buildings Random Daytime Sampling (RDT)[3] Samples are collected in wide-mouth 1L sample bottles, without removing the aerator, if present. (Note: AB protocols do not provide guidance on aerator removal).
A 1 L sample is collected randomly during the day from a drinking water tap. Samples are collected without prior flushing; no stagnation period is prescribed, to better reflect consumer use. (Same as Alberta).
To mitigate safety risks associated with using concentrated acid in the field, samples are acidified upon receipt at the laboratory to 2% (by volume) using concentrated nitric acid and held for a minimum of 16 hours after preservation before analysis[4].
30-minute Stagnation (30MS)[5] Samples are collected in wide-mouth 1L sample bottles, without removing the aerator, if present. (Note: AB protocols do not provide guidance on aerator removal).
The tap is flushed for 5 minutes, allowed to stand for a 30-minute stagnation period, during which time no water should be drawn from any outlet within the residence (including flushing of toilets). Two 1 L samples are collected at a medium to high flow rate (greater than 5 L/minute). The lead concentration is determined by averaging the results from the two samples. (Alberta 2 – 5 min. flush, otherwise the same).
To mitigate safety risks associated with using concentrated acid in the field, samples are acidified to 2% (by volume) using concentrated nitric acid and held for a minimum of 16 hours after preservation before analysis[4].
Schools, Multi-dwelling Residences and Large Buildings Random Daytime Sampling (RDT) In schools and daycares, it is recommended that total lead be monitored, at least once per year, at each of the drinking water fountains or cold water taps where water is used for drinking or food preparation. Sampling should be conducted between the months of June and October, but when the buildings are fully occupied.
In multi-dwelling (i.e., more than six residences) buildings or large buildings, it is recommended that total lead be monitored in a manner such that each of the drinking water fountains and a proportion of cold water taps is sampled within a specified period.
RDT sampling is conducted by collecting a sample at drinking water fountains or at cold water taps where water is used for drinking or food preparation, without a stagnation period and without prior flushing.
Two 125 mL samples are collected at a medium to high flow rate without removing the aerator. (Note: AB protocols do not provide guidance on aerator removal).

 

References

[1] Government of Canada: “Guidelines for Canadian Water Quality – Guideline Technical Document – Lead” (March 2019)

[2] Alberta Government: “AEP Guidance Document for Managing Lead in Municipal Drinking Water Systems in Alberta: Phase 1 tools for utilities to plan, assess and implement lead management plans for 2020-2024” Version 1.2 (November 2019)

[3] RDT sampling is typically used system-wide

[4] The use of concentrated acid (2% by volume) as the preservative is a significant difference from Alberta sampling protocols

[5] 30MS sampling is typically used at sentinel sites. The 30MS sampling protocol is normally used for investigating the cause of exceedances and identifying appropriate mitigation measures.