Flushing water pipes to help reduce the smell and taste
Council contractors have started flushing pipes in areas most affected by the smell and taste of chlorine.
In addition to flushing the pipes, staff are working with the appropriate health authorities to explore how we can reduce the amount of chlorine being added into the water supply.
He explains that the amount people notice the smell and taste can, among other things, depend on how close they are to the pump station. Different pump stations are used depending on demand so you may not be getting water from the one closest to you. The map below has been updated to show the location of all the pump stations.
Another factor is the condition of the pipes.
Chlorine reacts with a variety of naturally occurring materials in the pipe. It’s this reaction that can cause the variation in smell and taste in some areas and that’s why we’re flushing pipes in the worst-affected areas.
People storing water in the fridge are reminded to keep lids off containers so the chlorine can evaporate over time.
People with health issues that are experiencing increased symptoms should contact their GP.
Why there is variation in the taste and smell of water across the city
We've released some new information explaining why some people are detecting the chlorine in their water while others can barely notice it.
Through a question and answer section on Newsline, we explain that the chlorine dosing takes place at the pump station, not the individual well heads as some seem to think. From the pump station, the water flows directly out into our water reticulation system across the city. If you live close to the pump station, the chlorine dose you get coming out of your kitchen tap will be higher than if you live much further away.
The article also covers off topics such as why there is variation during the day and the impact of things like the condition of pipes on the taste and smell. It also looks at what other cities around the world do and if the situation will improve.
Council agrees on approach to well head work
A mix of options for upgrading the security of Christchurch’s groundwater supply will be pursued so the city’s drinking water can return to its natural, unchlorinated state as soon as possible.
On Thursday April 26, the Council resolved that its preferred approach to improving well head security was to raise well heads above ground wherever practicable.
It also agreed that staff should examine options for installing UV treatment at a number of pump stations where the Council may not be able to get secure status.
The advantage of UV treatment is it doesn’t affect the taste or smell of water —most bottled water is treated this way. It can be more expensive to implement UV treatment, and unlike chlorine, it doesn’t provide protection beyond the site where treatment occurs. However, where the installation of UV treatment replaces the need to upgrade a number of well heads it can be an economical solution.
We’re hoping to reduce the amount of time we need to chlorinate. With careful management of the various pump stations as well as limiting demand where we can, we may be able to provide enough unchlorinated water for the city.
A report will go to Council in May mapping out a draft programme for upgrading the water supply network.
Ferrymead and Lyttelton zones last areas to be treated
Temporary chlorination of the water supply in the Ferrymead and Lyttelton zones will start from 23 April 2018.
The Ferrymead zone stretches from Woolston east to Taylors Mistake and supplies 8,500 properties. The Lyttelton zone covers all the water supply zone for Lyttelton Harbour including Governors Bay and Diamond Harbour, supplying 3,000 properties.
These are the final two zones to receive temporary chlorination following on from the central zone. A single well in Wainui, servicing about 400 people, will be temporarily chlorinated from the end of April.
Temporary chlorination of the central zone will start during the week starting 16 April.
About 255,000 people are in the central zone, which stretches from Sydenham to St Albans and Papanui as well as across to New Brighton in the east.
Northwest treatment brought forward
Temporary chlorination of the water supply in the northwest zone of Christchurch will begin from Friday 6 April.
The northwest zone stretches from Belfast through to Yaldhurst and includes parts of Riccarton and Addington and supplies 80,000 people.
Treatment in the Riccarton zone (which is different to the northwest zone) as well as supplies in Sockburn and Hornby (the west zone) will also start from Friday 6 April.
Temporary chlorination starts in Brooklands/Kainga
The Council began the temporary treatment of the city's water supply in the Brooklands, Kainga and Spencerville area on Monday, 26 March 2018.
Following Brooklands/Kainga, which includes Spencerville, temporary treatment will be introduced gradually across the city, including Riccarton, Halswell, Parklands, the Heathcote Valley and Lyttelton Harbour.
The largest central zone will be last to be treated. It supplies 255,000 people from Spreydon and Cashmere as well as in Papanui and Grassmere and across to Linwood, Aranui and New Brighton.
It is expected that chlorination will be set up at all Council supplies in Christchurch city and Banks Peninsula by the end of April 2018.
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