Water withdrawal and consumption by sector indicator: data sources and methods, chapter 5

5. Caveats and limitations

While water is withdrawn for human use from both surface water and groundwater sources, most water is returned to surface water. The Water Withdrawal and Consumption by Sector indicator considers water to be consumed if it is not returned directly to its source. The possible depletion of groundwater resources due to economic practices, such as mine dewatering or municipalities using groundwater for drinking, has been captured in the indicator. According to the System of Environmental-Economic Accounting (SEEA) for water,^{Footnote [1]} water removed from a groundwater source and returned to surface water is not considered to be consumed because, although it is not returned to its original source under the ground, the water returned to a surface water body is still available for other economic uses.

Although efforts were made by Statistics Canada to reduce errors in the Industrial Water Survey (IWS), Agricultural Water Survey (AWS) and Survey of Drinking Water Plants (SDWP) through data validation, errors are unavoidable and are likely present in the data. Imputation was used by the IWS and AWS on partial-response records.

In the cases of the households, commercial and institutional, and oil and gas sectors, the estimates of the proportion of water withdrawn that is consumed could not be corroborated with recent studies or monitoring results.