How safe is Wellington's water supply?
The contamination of Havelock North’s drinking water is a crisis for both residents and the council. It begs the questions…. could it happen here? What are councils and Wellington Water doing to make sure it doesn’t?
The Wellington water network
Wellington Water’s catchment area covers Lower Hutt, Wellington, Upper Hutt and Porirua cities. It has three sources of drinking water; the Hutt River, the combined flow of the Wainuiomata and Orongorongo rivers and the Waiwhetu Aquifer - a natural underground reservoir that’s fed by river-water filtered through the ground.
Wellington’s water is sampled and tested in accordance with the Ministry of Health’s Drinking Water Standards for New Zealand. The standards set out the sampling rate for the population served and the tests that must be carried out on all samples.
We carry out about 5,700 samples a year, at nearly 500 sites across the four cities. Sampling rates are also determined by whether or not the water is chlorinated. As most of Lower Hutt’s water supply is not chlorinated, it’s subject to more sampling than water for the other cities.
Because it is impracticable to monitor water supplies for all potential pathogens (bacteria that cause disease), E. coli is used as an indicator organism for faecal contamination of drinking water.
If a sample tests positive for E. coli, the water is resampled at the original and adjacent sites, an investigation and physical inspection is carried out on the affected area, and corrective action taken. Depending on the number of bacteria (or colony forming units) counted in the sample, this could include a boil water notice being issued and a reservoir or network could be dosed with chlorine to kill any bacteria present.
Wellington Water continues to monitor and manage the water supply system to ensure its safety, and will take close note of the learnings from Havelock North.
Water supply resilience
Our region is vulnerable to the risk of water supply interruption - this to due to our geography and where our water sources are located. Widespread damage of the reticulation network could take many weeks to repair which could have severe implications for our economy. We're working on improving the resilience of our water supply - to find out more, check out this information.
Upgrading your washing machine or shower?
Panel approach picked to bring regional benefits
We're pleased to announce that we've reached an agreement with three engineering groups to provide consultancy services for water supply, wastewater and stormwater infrastructure development for our council clients.
More information can be found here.
Vancouver St (Kingston) and Armour Ave (Mt Victoria), water main renewal
The water main in Vancouver St, Kingston and in Armour Ave, Mt Victoria will be renewed, with work beginning on 13 July 2016. This work is expected to take 12 weeks to complete.
The contractor is Wellington Pipelines Ltd (James Fruean, 027 499 9223).
Waru Street (Khandallah), water main renewal
The water main in Waru Street, Khandallah is being renewed. Work began in July 2016 and is scheduled to be completed in mid October. The contractor is Groundworks Ltd. Read more on this project here.
Hobart Street (Miramar) and Kaikoura Street (Maupuia), water main renewal
Work to renew the water main in Hobart St, Miramar and in Kaikoura St, Maupuai will begin on 11 July 2016. This work is expected to take 12 weeks to complete.
The contractor is Dews Construction Limited (Sam Dews, 027 592 2290)
David Crescent (Karori), water main renewal
Work to renew the water main began on 23 June and is expected to take 12 weeks to complete.
The contractor is Te Aratika Drilling Limited (Robbie Bracken, 021 881 479)
Queen St (Petone), stormwater and wastewater renewal
Work to renew the stormwater and wastewater pipes began on 4 July and will be completed by December.
For more information, check out this project page.
Molesworth Street (Thorndon), stormwater and wastewater renewal
Work to renew the stormwater and wastewater pipes buried beneath Molesworth Street is scheduled for completion in November 2016.
The work involves replacing pipes from Little Pipitea Street to just past the motorway on-ramp (87 – 133 Molesworth Street). Read more about this job here.
New Melrose reservoir bigger, stronger, safer
Work has been completed on the new reservoir in Mt Albert Park – part of an ongoing programme to make the Capital’s water storage facilities and supply network stronger, safer and better able to meet the needs of a growing population.
The new reservoir, being managed by Wellington Water on behalf of Wellington City Council, will provide three times more water storage for the Melrose area.
Reservoir, what reservoir? Burying the reservoir is almost complete
Wellington City Council has done a lot of work over the past 20 years to earthquake-strengthen existing reservoirs, build new ones to stringent seismic standards and install automatic shut-off valves so the tanks don’t empty if the pipe network is damaged.
About 66 percent of the water in the city is now stored in reservoirs that have been seismically strengthened and more than 95 percent have shut-off valves.
The new Mt Albert Park reservoir will be more resilient during a severe earthquake and also allow for population growth over the next 80 years. It will replace the older of the park’s two reservoirs, which was built in 1910.
Catchment management planning
We're working on a long term plan to improve the management of stormwater in Wellington City. Stage one of the plan looked at the characteristics of Wellington's 34 sub-catchments. In Stage Two, we'll develop action plans for five groups of catchments.
More information and the Stage one report is available. You can also read the Annual Report on the stormwater discharge consents, showing the performance of Wellington City's stormwater catchments.