With chlorination of Blenheim’s water supply due to start by late October, work begins today to prepare the town’s water mains.

“Before chlorine is added, engineers need to thoroughly flush and test the water reticulation pipes via each hydrant to prepare the network,” Planning and Development Engineering Manager Mark Power said.

“Sediment and bacteria can build up in water pipes, which produce a slimy lining on the walls called biofilm. The most effective way to remove this is to flush the entire network,” Mr Power said.

“We need to do this prior to introducing chlorine to the network to make sure the pipes are ready. It also enables us to test valves and hydrants as we go.”

Around 1200 hydrants in Blenheim and Marlborough Ridge will be flushed over a five-week period from today. Each hydrant takes around 30 minutes to be flushed.

“We will have three teams on the job including a nightshift crew. It’s not a noisy process but residents may notice a bit of surface water near the curb when hydrants are flushed in their area,” Mr Power said.

“As this work will be stirring up the pipes, people may also notice some discolouration, taste or odour in their tap water, but this will be short lived. Run your tap first thing in the morning for 30 seconds to help alleviate this.”

Chlorination is required to ensure Blenheim’s supply complies with the Government’s Water Services Act and drinking water quality assurance rules. The Water Services Authority Taumata Arowai requires a residual disinfectant - typically chlorine - to be added to all reticulated water supplies in New Zealand.

Chlorine is a simple and effective way of ensuring water is fully disinfected and safe for drinking. It’s used worldwide to purify water supplies as it kills most common bacteria including campylobacter and norovirus. It’s used alongside other processes such as protozoa barriers which remove or inactivate single-celled parasites including cryptosporidium and giardia. Water supplies in Renwick, Picton, Havelock, Wairau Valley, Seddon and rural Awatere are already chlorinated

Blenheim’s water, which is delivered to 10,700 households, is currently treated for protozoa and bacteria, but has no chlorine dosing.

“Chlorine will be introduced to the Blenheim supply by late October, starting with a low dose. We will be monitoring how quickly it moves through the network and testing until it is present at the required level.”

“For a short period following chlorine’s introduction, residents may notice a taste and smell. There are solutions to this, such as filling a jug of water and leaving it on the bench or in your fridge overnight, or you can install a household carbon filter. For anyone with a skin condition sensitive to chlorine, you can get filters on shower heads,” Mr Power said.

Council will also install four chlorine-free water fountains around town for people to fill containers up to 20 litres. These are planned for A & P Park (Alabama Road), Lansdowne Park, Forest Park Drive and Horton Park.

Council has published information online and as a pamphlet on the introduction of chlorine to the Blenheim supply. For more information go to https://links.marlborough.govt.nz/Blenheim-Water-Supply

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