Check here for the latest information on the work that is being done to return Christchurch's water to an unchlorinated state.
Friday, 17 August
A $2 million investment in ultra-violet (UV) light disinfection could bring an end to chlorination at Christchurch’s largest water supply pump station.
Next Thursday the Council will consider a report that recommends installing UV light disinfection at the water supply pump station at the south end of Colombo Street.
Monday, 13 August
Chlorine treatment has stopped at a further three pump stations — Grampian, Lake Terrace and Hills — in the city.
Now that the below ground well heads have been isolated, unchlorinated water can be supplied from the secure above ground well heads at these pump stations.
Hills supplies about 9000 people, and Lake Terrace and Grampian each supply about 1500 people.
The actual number supplied by any pump station depends on demand and how many pump stations are operating across the network.
Nine pump stations across the city are not being treated with chlorine, although as demand increases the Council may need to start using below ground well heads. If that is the case, the water will need to be chlorinated.
Wednesday, 8 August
Work to improve the security of the Christchurch’s water supply is moving forward, with the approach confirmed for upgrading 72 of the city’s wells.
Good progress is being made on the initial round of work on 23 wells at seven pump stations which will allow chlorination to stop at those pump stations. There is now a confirmed approach for a further 49 wells at 17 pump stations.
Tuesday, 31 July
Chlorine treatment has been stopped at the Burnside and Farrington pump stations in the north-west supply zone.
This is the result of minor remedial work on the above ground well heads to enable them to be signed off as secure.
Friday, 20 July
We’ve added some new layers to our chlorine map(external link) and created a new section on our website for water supply projects.
The map now shows you where the well heads are and which ones are included in the first stage of works.
On the water supply projects section(external link) you’ll find information about new wells and pump stations, well head improvements, and alternative disinfection methods.
Tuesday, 10 July
Minor remedial works are being carried out on 23 above ground well heads, at seven pump stations, to enable these well heads to be signed off as a secure. We expect the works to be completed and inspections undertaken by the end of this month.
An isolation procedure has been agreed for the remaining below ground well heads which will allow chlorination to cease, early in August, at these pump stations:
Investigations have shown that ultra violet (UV) light disinfection is feasible and we are assessing the costs and benefits of using UV at a number of pump stations.
Preliminary design work has been completed for UV disinfection at Main Pumps, in Beckenham, in the central supply zone. A report will go to the next meeting of the Council’s Infrastructure, Transport and Environment Committee recommending the Council seek tenders for the work.
Thursday, 28 June
We've been looking into alternatives to chlorine such as ozone and UV light treatment.
We have rejected ozone as a suitable disinfection agent because our analysis has determined it is incompatible with the chemical composition of our groundwater.
Ultra violet (UV) light is an option we are pursuing and we are assessing the costs and benefits of using UV at a number of pump stations.
Preliminary design work is under way for UV disinfection at Main Pumps in the Central zone. Subject to costs and availability of equipment, this is proposed for construction to begin late 2018.
Tuesday, 26 June
A further two pump stations have been identified where below ground wells can be isolated and unchlorinated water provided from above ground well heads.
The new sites are at Lake Terrace in Burwood, and Thompsons Road in Northwood.
It is possible that if demand increases, or in the event of a fire, we may need to start using the below ground well heads and then the water would need to be chlorinated.
Thursday, 14 June
Council is targeting work on further pump stations to improve well head security in order to stop chlorinating the water at those pump stations.
The pump stations involved have a mix of above ground and below ground well heads.
The pump stations identified for remedial works are: Grampian, Farrington, Burnside, Grassmere, Hills and Mays.
Friday, 8 June
Due to public interest in the amount of physical work that has been done on the city’s water infrastructure since it lost its secure status, here is a summary of work done:
Between January and May, minor remedial work has been done to improve safety and security at 22 of our 53 pump stations that were assessed as having the highest risk of contamination to below ground well heads. This work varied across the sites and generally included:
While these works reduce the risk of contamination, they are not sufficient to meet the new, stricter, interpretation of the standards for well head security. These pump stations and well heads are included in the future work programme to determine the best approach to allow us to return to an unchlorinated water supply.
Work has also been done at our new pump stations, with above ground well heads, across the city. There are four pump stations with 11 well heads that, while designed to best practice, would not have meet the stringent new standards being upheld. These were assessed in January and remedial works have been completed.
All 11 well heads have now been signed off as secure and the water supplied by the four pump stations (Prestons, Estuary, Keyes and Gardiners) is not being chlorinated.
We are continuing our ongoing work to reduce the impact of the chlorination.
As well as flushing pipes with fresh water to remove the natural organic matter that causes the smell and taste, we are managing the dose level and reducing it where we have been given approval to do so. We are also looking at measures to increase the use and capacity of our non-chlorinated sites so there is a greater quantity of untreated water in the network.
Thursday, 7 June
Council Chief Executive Karleen Edwards has created a new role to focus exclusively on improvements to the drinking water supply.
For the next 12 months, Helen Beaumont will be in the role of Programme Manager – Water Supply Improvement reporting directly to the chief executive. This is a secondment from her current role as Head of Strategic Policy.
Thursday, 31 May
We've updated our pump station map to colour-code the stations that are not being treated ‑ Estuary, Keyes and Prestons. These appear green while the others standard blue.
As we work through the process of changing the dose rate at pump stations this information will be added. It will take a few weeks to implement the change. The status of those pump stations will also be differentiated in a different shade so you can see at a glance what's happening across the network.
We are still working to get the test results added to the map and hope to be able to do this soon.
Wednesday, 30 May
You might have heard about, or read, an article on the Newstalk ZB website about our decision to reduce the chlorination dose rate at some pump stations, which included some statements from Medical Officer of Health Ramon Pink.
Dr Pink is unhappy with the way his lengthy interview was presented and has been on air this morning to clarify his statements.
As we announced earlier this week (see below) we have an agreement with the Drinking Water Assessor to reduce the amount of chlorine at pump stations where we have a contact time of two minutes. We are targeting a rate of 0.5 parts per million where we have two minutes' contact time.
Monday, 28 May
Christchurch City Council is starting to lower the amount of chlorine it is putting in the water at some of the city’s pump stations in an attempt to address taste and smell issues.
“We have already been given approval by the Drinking Water Assessor to reduce the dose of chlorine at 27 of the 53 pump stations that are being treated,’’ says Council General Manager City Services David Adamson.
This will reduce the overall concentration of chlorine in the drinking water.
“We are hoping reducing the dose will help with the taste and smell issues that some people have been experiencing but until we roll this out we cannot make promises.
“The advice we have had from our independent expert suggests the lower dose could reduce the taste and smell issues, but there is a chance it may not make a significant difference.
"That being said, both our expert and the Drinking Water Assessor believe the potential benefits outweigh that risk and it is worth shifting to a lower dose where we can,'' Mr Adamson says.
The 27 pump stations where the Council will be lowering dose have been selected because they are in areas where the water travels down the pipes for at least two minutes before reaching people’s homes.
That two minute lag is important because it allows enough time for the chlorine to be effective at a lower dose.
At the other pump stations the chlorine only has a minute’s contact time with the water before people start drawing on it so the dose needs to remain at current levels, until alternative measures can be put in place.
"There is some work to be done at each of the affected pump stations in order to change the dose so the lower dosage will be rolled out progressively over the next couple of weeks. We'll be updating our online map(external link) to indicate the dose rate at each pump station.
“We will be closely monitoring the impact of reducing the chlorine dosage and will continue to have ongoing discussions with the Drinking Water Assessor about how we can reduce the amount of chlorine in the network,’’ Mr Adamson says.
“This week we will also be continuing the work we are doing to flush the pipes with high pressure water in the suburbs that seem to be noticing the taste and smell of chlorine the most. Hopefully that too will help reduce the short-term taste and smell issues.
“Longer term we are looking at a range of options including treating the water with ultra-violet or ozone. We are prioritizing our well head improvement work on those pump stations where we are most likely to get approval to stop chlorinating. We are also looking at water demand and the way we use the network so that we can provide as many people as possible with unchlorinated water,’’ Mr Adamson says.