Laboratory sample ID. The City of Toronto has no control over how or where a sample is obtained.

Sample Date is the date sample was collected by resident.

First three digits of postal code from residential property where sample was submitted from. For privacy reasons, only three digits of postal code is available on Open Data.

ppb = parts per billion µg/l = micrograms per litre mg/l =milligrams per litre

The Ministry of the Environment and Climate Change's Ontario Regulation 169/03 sets the maximum acceptable concentration of lead in drinking water at 0.010 milligrams per litre (mg/l) or 10 parts per billion (ppb).