A dead seagull that somehow got into the Waterloo Pumping Station once famously contaminated Lower Hutt’s drinking water.
That was in 1991. The more recent source of contamination still has experts scratching their head.
Lower Hutt residents have long been proud of the water that comes from the Waiwhetu Aquifer.
Aquifers are under pressure from development and contamination all over the world, but Lower Hutt’s water supply has always been regarded as pristine.
* Hutt authorities to continue treating water
* Boil water notices plague West Coast* Power cuts likely cause of E-coli contamination
That was until three recent positive tests for E-coli, which could point to a major problem
Although the latest test found no trace of the nasty stomach bug, chlorine is now being added to the water. Two popular artesian wells are also closed.
An investigation into the source of the contamination is expected to take many months but one intriguing theory is that the November earthquake caused the problem.
The aquifer runs underneath Lower Hutt and whenever there is major work, such as a new building or a new bridge, there is always a concern about its impact on the aquifer.
Once an aquifer is compromised by seawater or contamination, the quality of the water quickly deteriorates and it is almost impossible to reverse. That is why there is so much concern about the Waiwhetu Aquifer.
Former GNS scientist Jim Cousins said the earthquake was a possible cause of the contamination.
It takes a year for the water to travel through the underground gravels from Taita to Waterloo, where it is pumped out for drinking.
It is the process of soaking through the gravel that cleans the water of bugs and bacteria.
The presence of E-coli suggests the contamination is recent, which could mean a newly-formed crack in the aquifer, Cousins said.
“That would be a serious worry amongst the water supply people.”
In October 2015, GNS scientist Dr Uwe Morgensterm reported that he had successfully dated the water in the aquifer.
Although it had always been assumed the water was safe to drink, Morgensterm’s research confirmed its safety.
Greater Wellington Regional Council senior environmental scientist Douglas Mzila said people generally do not understand what a valuable asset the aquifer is.
Scientists are puzzled about the source of the contamination and he predicts it will take a lot of detailed work to pinpoint the cause.
He is aware of overseas research that shows large earthquakes have damaged aquifers.
“That is not to say that has happened here but there are studies that show earthquakes can have an impact.”
The aquifer has been well managed over a long period of time and although the E-coli finding is yet to be explained, the water quality remains good, Mzila said.
But with chlorine being added to Lower Hutt’s drinking water, we asked the Hutt City Council some questions about what is going on.
Recent water quality tests have come back clear, why are you still chlorinating?
We are seeing a trend of increased bacteria activity in the aquifer which, together with the recent positive E.coli indicator test, we are treating as a signal for further investigation. We’re exercising a high level of caution and are continuing to chlorinate the water we take from the aquifer while evidence is gathered around why this is happening. Public safety is our number one priority, which means we have to chlorinate as a precaution.
What do the health authorities say?
Regional Public Health is satisfied with the measures put in place to ensure the water is safe and advise there is no need to boil it before drinking.
What is the history of positive E.coli test results in comparison to this year?
In the last five months, we’ve had three positive E.coli results in Lower Hutt. These tests are a sign that further testing is needed. In all three cases, further tests came back negative. However, two of these recent positive results have come from the water source, not the distribution network. Before December 2016, we hadn’t ever had a positive E.coli result from the aquifer source. More specifically, there is also an increasing number of Total Coliforms (indicator bacteria) being found in the source water. This is an indication that something has changed within the aquifer and further investigation is needed.
How long will the aquifer water be chlorinated for?
This depends on the results of Wellington Water’s investigations. These investigations are expected to take a number of months to complete and the water sourced from the aquifer will remain chlorinated during this time. We are seeing a trend of increasing bacteria activity across the aquifer which, together with the recent positive E.coli indicator test, we are treating as a signal for further investigation. We’re exercising a high level of precaution and have closed the public fountains as they can’t be chlorinated. They will remain closed while Wellington Water investigates; this is likely to take months to complete.
Why didn’t you shut the public fountains the first two times E.coli was found?
Only recently has the number of Total Coliforms found in the aquifer water been increasing. This, plus the third positive E.coli result in five months, led to the decision to keep chlorinating the Lower Hutt water supply network and to close the public fountains.
I haven’t been feeling well for the past few days, could this positive E.coli result be the reason?
No. Your tap water has been, and remains, safe to drink. If you have any health concerns please see your doctor or contact Healthline (0800 611 116).
Is the water safe to drink for children and the elderly?
Yes, the tap water has been, and remains safe, to drink.
How likely is it that the aquifer water will be permanently chlorinated?
A decision on the permanent chlorination of Lower Hutt’s aquifer water has yet to be made. This decision depends on the result of Wellington Water’s investigations and further discussions between Regional Public Health, Greater Wellington Regional Council, Hutt City Council and Wellington Water.
The earthquake was in November 2016, why have you waited until now (five months later) to decide the aquifer needs to be investigated?
Wellington Water has been carrying investigations into the aquifer since the earthquake. These investigations will take a number of months to complete.
Is this related to the November 2016 earthquake?
It may be as the recent positive E.coli results and the increasing bacterial activity in the aquifer water started after the earthquake. Wellington Water will be looking into this as part of their investigations.
Is this related to farming?
No, the aquifer is located below an urban area.
What if I have drank from the fountain recently?
Water quality tests at other locations taken at the same time as the positive E.coli test (and since) have been negative. The public fountains have been closed as a precaution as they can’t be chlorinated.
Is there any place in Lower Hutt to get access to unchlorinated water now?
No. If your water has a chlorine taste, try putting the water in a container or jug in the fridge (this helps the chlorine dissipate from the water). Boiling the water also helps take the chlorine taste out of the water. You may find that using a water filter that uses carbon filtration helps. Please consult the manufacturer’s instructions on recommended use.
Is this issue similar to the water quality incident in Havelock North last year?
No. Havelock North had a number of unwell residents (that was traced to the water supply) while we have none. The elevated bacterial level in our aquifer water is an indicator that we need to investigate and we are taking a precautionary approach by chlorinating the water supply.
Now that chlorine has been added to our water supply, will fluoride be added to the water supplied to Petone and Korokoro?
Our focus is on investigating the positive E.coli test results and the increased bacterial activity in the source water. There are no plans to change the current fluoride status in Petone and Korokoro.
Is this just a ploy to permanently chlorinate the water because it’s easier to do?
No. A decision on the permanent chlorination of Lower Hutt’s aquifer water has yet to be made.
What are Total Coliforms and why are they a concern?
Total coliforms refer to a group of 16 different types of bacteria. These bacteria are found in soil, vegetation, animal waste and human sewage and many are not harmful. Total Coliforms can be an indicator of the existence of a potential pathway for contamination of the aquifer. This is being investigated.
I have a private bore. Is it safe to drink from it?
No, we recommend that you do not drink water taken from a private bore.
* Wellington Water delivers about 140 million litres of safe drinking water to the people of metropolitan Wellington every day.
* A routine water quality test on water from a bore in the Waterloo wellfield (Lower Hutt) returned a positive E.coli result on April 12. Other recent positive E.coli results were on February 4 and December 2, 2016.
* Chlorination of the water network in Lower Hutt was immediately initiated after each positive result.
* About 70,000 customers in the Lower Hutt usually receive unchlorinated water supply (residents of Wainuiomata, Stokes Valley and Manor Park already receive chlorinated water) and about 330,000 customers in Wellington, Porirua and Upper Hutt already receive chlorinated water.
* Metropolitan Wellington’s water comes from an aquifer, rivers, and, in times of shortage, storage lakes. Water from the rivers and lakes is chlorinated before delivery. Water from the aquifer usually isn’t chlorinated.
* The addition of chlorine to the water as a precaution against contamination means that the water doesn’t need to be boiled before drinking.
* As part of their investigations, Wellington Water will be looking at non-chemical treatment options that will allow the public fountains to be reopened.