With the start of summer and water levels in the Whanganui River dropping testing before and after treatment at the Taumarunui Water Treatment Plant is being stepped-up to ensure that the carbon dosing to help remove any taste and odour issues is working at the optimum level.
Acting Environmental Manager Stuart Watson said that warmer weather and low, clear flows in the Whanganui River was often when people started noticing any taste and odour issues with Taumarunui's drinking water.
“Since we started carbon dosing to help manage taste and odour the level of complaints has dropped significantly however we sometimes still have issues when we have these environmental conditions aligning.
Our rivers are living things and the taste and odour is affected by naturally occurring organic compounds such as algae and diatoms in the river.
These become more concentrated during periods of warm weather and low water flow which is compounded by water taken off to generate electricity,” he said.
“As a natural ecological system our rivers are always changing and Veolia needs to constantly work to keep things in balance.
In extreme weather events such as low river flows or floods this is more difficult to do.
The carbon works by bounding with the organic particles which is then filtered out.
When the water is running very clear after long still periods there is not much for the carbon to bind too which makes it less effective.
Unfortunately, sampling of both the raw water line and the treated water to try and determine how well the carbon is working has shown that adding extra carbon when the river running low doesn’t help the taste and odour issues much.”
Mr Watson noted that one thing people can do to help is to run their taps for a few minutes at the start of each day.
“This can help reduce any buildup of matter that can contribute to taste and odour issues,” he said.
“Likewise, depending on the situation Veolia can flush the out the pipe network by opening fire hydrants to get movement through the system.
People should also note that despite any minor taste or odour issues all Council supplied tap water is treated and 100% safe and will not cause people to be ill.
If people are experiencing anything, please call Council on 07 895 8188 and let us know.
This will allow us to run tests on the reticulation line to determine if flushing may help.”
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