Tokomaru’s tap water is safe to drink once more following days of a “do not drink” notice in place due to levels of lead.
Horowhenua District Council first put the order in place on August 7 after enhanced testing found non-compliant levels of lead in both the reservoir at the Tokomaru water treatment plant and the reticulation network.
A water tanker was dispatched to the Tokomaru community hall and bottled water was provided to residents from a local school and early childhood centre, according to the council.
Test results received last night concluded Tokomaru’s Water Supply was now compliant with New Zealand Water Standards and the Do Not Drink Water Notice was lifted “effective immediately”.
“Results from 18 separate samples across the network show that earlier concerns relating to elevated levels of lead and non-compliance, were as a result of plumbosolvency caused by water reacting with older tapware.
“Consecutive results received from this enhanced testing regime conclusively show that testing to date has not found lead contamination in the source water or the reticulated water supply.”
‘Hard’ versus ‘soft’ water
Tokomaru Water Supply — and many places in New Zealand — was classed as “soft” based on its amount of trace minerals.
This meant for Tokomaru, the water was more reactive to alloys such as in tap fittings. To mitigate this, further work would be done to harden the water – in the case of Tokomaru, increasing the ph level of the water, so that it was less reactive to tap fittings. This did not affect the safety of the drinking water.
What is plumbosolvency?
In many places in New Zealand, drinking water was plumbosolvent. This meant the water could dissolve small amounts of metals it might encounter, including lead and copper in plumbing fittings, such as pipes and taps.
Drinking water suppliers have a duty to ensure that the water they supplied complied with the Drinking Water Standards, which set maximum levels for metals in water.
However, there might be metals in the plumbing within properties such as in the taps or other fixtures, which could have an impact after the water has been supplied. Health NZ recommended running a tap to fill a large cup of water when it was first turned on each day.
What should residents do now?
A public meeting would be held at the Tokomaru Community Hall at 6pm on August 12, where Council Staff, Elected Members and Health NZ Medical officer of Health for MidCentral, Rob Weir and Peter Wood from Taumata Arowai would be available to answer questions from the public.
What about other water supplies in the Horowhenua?
Routine samples taken on August 1 from treated water at Levin, Shannon, Foxton and Foxton Beach Water Treatment Plants were all compliant with New Zealand Drinking Water Standards, the council said.
