Drinking Water Safety
Water is one of our most important assets. Residents, industry, businesses and farms depend on a supply of safe, affordable water.
Council is vigilant in monitoring the water supply. The Drinking Water Standards require routine monitoring of total coliforms and in particular testing for E.coli.
If E.coli or any other bugs are identified, daily samples are taken around the scheme at Otago Regional Council approved sample locations.
Council also liaises with the District Health Board to ensure correct and appropriate decisions are made when water quality is not optimum.
If E.coli is detected at a certain level then the boil water notice is put in place until Council gets at least three clear days of zero E.coli.
This is to ensure contaminant free, chlorinated water has had enough time to mix with the existing water in the tank and make the water in the tank safe to drink.
Council realises that it can be quite an inconvenience but the notice is in place to keep you and your family safe.
There are two pieces of legislation that control the quality of Council-supplied water, the Health Act 1956 and the Drinking Water Standards 2006 (Revised 2008). These deal with not only water quality, but with monitoring and data collection too.
Council is also required to have Water Safety Plans to guide the safe management of supplies and identify any potential risks.
Boil Water Notices
Visit our Boil Water Notice FAQ's page to learn more about what you need to know if your drinking water has had a Boil Water Notice issued.
Testing Our Water
To keep us all safe, it is important that the quality of the water being supplied to everyone in the Clutha District is regularly monitored. Council uses an external contractor to look after the day-to-day management and operations of the water supply network in Clutha District. Our water treatment plants are operated by trained staff, and samples are sent to a IANZ (International Accreditation New Zealand) accredited laboratory for analysis.
Example of Water Treatment
- Intake: Water is taken from the source. Logs, fish, and plants are screened before the water is drawn into the treatment plant. If the source is groundwater, the “screening” is done by ravels as the water travels under the earth’s surface. Sometimes very little treatment is required for groundwater.
- Chemical Addition: Chlorine, aluminium sulphate (alum), and/or polymers are added to the water. These kill germs, improve taste and odour, and help settle solids still in the water.
- Coagulation and Flocculation: Here, the alum and other chemicals from the chemical addition step cling to substances in the water. This is called coagulation. It causes the particles to stick together and form larger particles called floc.
- Sedimentation: The water and the floc particles flow into a sedimentation basin. Here the floc settles to the bottom, and is removed.
- Filtration: The water then flows through filters. There are a variety of filter types, from layers of fine sand and gravel to modern membranes. The filters are used to remove any particles remaining in the water.
- Chlorination: A small amount of chlorine is added to kill any remaining germs, and to keep the water safe as it travels to the public.
- Storage: The water is stored in a closed tank or reservoir. This allows time for the chlorine to mix throughout the water so that disinfection takes place before the water flows out for distribution.
Our Water Treatment Plants
|Treatment Plant||Treatments||E. Coli Sampling Frequency||Fluoride Sampling Frequency|
|Balclutha||Chlorination, UV (1),coagulation, sedimentation, filtration, fluoride (2)||Twice weekly||Weekly|
|Clydevale-Pomahaka (3)||Chlorination||Twice weekly||N/A|
|Glenkenich||Chlorination, direct sand filtration||Twice weekly||N/A|
|Kaitangata||Chlorination, coagulation, sedimentation, filtration, fluoride||Twice weekly||Weekly|
|Lawrence||Chlorination, UV, coagulation, sedimentation, filtration||Weekly||N/A|
|Milton||Chlorination, coagulation, membrane filtration, fluoride||Twice weekly||Weekly|
|Moa Flat||Chlorination, coagulation, direct sand filtration||Twice weekly||N/A|
|North Bruce||Chlorination, direct sand filtration||Twice weekly||N/A|
|Puerua||Chlorination, coagulation,sedimentation, filtration||Twice weekly||N/A|
|Stirling||Chlorination, coagulation,sedimentation, filtration||Twice weekly||N/A|
|Tapanui||Chlorination, coagulation,sedimentation, filtration, fluoride||Twice weekly||Weekly|
|Waitahuna||Chlorination, coagulation,sedimentation, filtration||Twice weekly||N/A|
|Whitelea Road||Chlorination, coagulation,sedimentation, filtration||Weekly||N/A|
(1) Ultra Violet (UV) light is used to prevent any organisms present from reproducing, and so limiting their ability to harm people. It works on protozoa (cryptosporidium and giardia), bacteria and to some extent on viruses.
(2) Fluoride is added to boost the natural level of fluoride in water to a level that helps protect against tooth decay. The decision to add fluoride is taken by the local DHB.
(3) The water for these schemes is groundwater-sourced, and less treatment is needed to make the water safe for use.