Lead
Drinking Water Quality Testing - Lead
While lead is a naturally occurring metal it is not common in New Zealand drinking water sources. The most likely reason lead can be found in drinking water is when plumbing materials that contain lead corrode and leach into the drinking water. The amount of lead dissolved will depend on the characteristics of the water and how long the water has been sitting in the pipes. If lead is detected in source water samples the cause can often be tracked to the plumbing associated with the sample tap rather than contamination or naturally occurring lead in the environment.
This page shows the Selwyn's District Council's testing results for lead for water sources used for drinking water measured in g/m3. The drinking water that comes from our network is safe to drink. However, materials used in home plumbing systems may contain lead and New Zealand water can be slightly acidic, which can dissolve metals (called plumbosolvent water). It is therefore recommended that all households flush a large glass of water from your drinking water tap each morning before using any water, in order to flush out the water sitting in your pipes overnight. The drinking water authority Taumata Arowai has published more information on their website.
Taumata Arowai is responsible for setting the New Zealand Drinking Water Standards, which specify the maximum amount of different chemicals, including lead, that are safe to have in our drinking water. This is known as the Maximum Acceptable Value (MAV). In most cases the limits are based on the level of risk from a lifetime of drinking the water.
Select a scheme boundary to find the most recent lead result for each source. Data is updated monthly.
When you click on the map the colours shown represent the lead level compared to the Maximum Acceptable Value (MAV) of 0.01 g/m3. The colours show lead levels of:
| value less than 0.005g/m3 |
values between 0.005g/m3 & 0.01g/m3 |
value more than 0.01g/m3 |
Explore lead readings over time
The Water Scheme filter applies to the table and graph below.
Explore lead readings over time
The Water Scheme filter applies to the table and graph below.
Lead testing and frequency
The drinking water regulator Taumata Arowai sets a frequency of testing source depending on the population which ranges from no requirement to test to annually for supplies with a population of over 500 people. Selwyn District Council has chosen to test all drinking water sources annually.
Selwyn District Council also tests the water within the distribution network to check the level of lead in pipes delivering water to households.
All samples are analysed in an IANZ Accredited Laboratory. The detection threshold for lead is 0.0011 g/m3. New Zealand’s water legislation sets required units as “mg/L”, which is a different way of expressing g/m3.