A key indicator of groundwater contamination by microorganisms, some of which can cause diseases. Faecal bacteria from livestock, onsite wastewater discharges, stormwater and other sources can contaminate groundwater. See the LAWA E. coli factsheet for more information.
Map usage: Drag and scroll on the map to move and zoom in on areas of interest, click on a site circle to see more information and subset the table below to that specific site, and use the selection box on the map ( ) to subset table data to sites in that area.
Table usage: All calculations use E. coli (cfu/100ml). Click on the +/- button at the end of a row to see the raw sample data and highlight that site on the map above. Click on table headers to sort the data by that column – holding the shift key allows sorting over multiple columns.
| DWSNZ MAV (cfu/100mL) | No. Sites |
|---|---|
| Detected (≥1) | 18 |
| Not detected (<1) | 37 |
| Total sites | 55 |
E. coli is an indicator of faecal contamination in drinking water. The Drinking Water Standards for New Zealand (DWSNZ) sets a Maximum Acceptable Value (MAV) for E. coli in drinking water supplies of less than 1 in 100 mL of sample.
Shallow groundwater within Connectivity Category A (direct) poses a greater risk to water quality in the surface water system than groundwater within other Connectivity categories. See groundwater connectivity for more information on surface water connectivity categories.