Water quality

Nelson's water supply and distribution quality is assessed every year by the Ministry of Health.

They look at two things:

  • Water supply quality (how good is the water at the source, after any treatment)
  • Water distribution system quality (how good is the water when it arrives at the tap)

The Ministry of Health suggests that the minimum water supply grading for a community with more than 10,000 residents be:

  • Level 'B' for source and treatment
  • Level 'a' for distribution

Nelson's water quality at the most recent assessment, in 2011, was:

  • Level 'A' for source and treatment (completely satisfactory, extremely low level of risk)
  • Level 'b' for distribution (satisfactory, very low level of risk)

Works underway in next few years – providing additional storage, backflow protection and a duplicate Maitai pipeline – should maintain the current grading and may lead to a higher grading for our water quality.

For more information on Nelson's water planning, see the Water Supply Asset Management Plan. You can also learn about Nelson's water treatment plant.

Changes in water clarity

There are a number of factors that can result in the water coming out of your tap looking discoloured. These include seasonal temperature changes, water mains repairs or replacement work, which can all cause this issue.  In almost all cases, this is temporary and will quickly settle down.

Here’s what to do if your water isn’t clear

The first thing to try if you are concerned about discoloured water is to run your tap for around 10 minutes. You can stop sooner if the water runs clear.

If you are still concerned after 10 minutes of running the tap please call our Customer Service Centre on 03 546 0200 and we will arrange for a contractor to flush pipes in your area.

Or you can fill out a Fix-a-gram form to report the issue here

When we are aware of problems with discoloured water in a certain area we also carry out proactive flushing of the water mains in an effort to resolve the problems as quickly as possible.

Drinking water is constantly monitored

Council has systems in place to monitor water quality and testing is increased in areas where discoloured water is reported to ensure that it is always safe to drink.

Every time our contractor flushes a water main, a sample of water is taken and sent for test.

In all cases, if you have concerns about discoloured water please contact us on 546 0200 so we can address the issue quickly.

Stain removal using Oxalic Acid

If your washing has been affected by discoloured water, oxalic acid can help to remove any stains caused by the water. Read more here (92KB PDF).