The recent lead contamination scare in east Otago has raised the question, how safe are New Zealanders with their drinking water?
The technical manager at industry group Water NZ said he would not drink what comes out of the tap in some areas of the country.
Waikouaiti and Karitane are being offered free blood tests after Dunedin City Council eventually revealed there had been serious but intermittent spikes in lead levels in their drinking water in late 2020. One result was 40 times the acceptable level.
The council has no idea what has caused the contamination, but it is now replacing about four kilometres of old cast iron pipes in the network that have lead joins.
Water NZ is the industry body for the Three Waters sector - drinking water, wastewater and storm water - with more than 2300 members including water technicians, researchers and consultants.
The group's technical manager Noel Roberts told Checkpoint lead can exist in older pipes that are still used in New Zealand.
"Older pipes, and we're talking over 100 years old like cast iron pipes in particular, often use lead as a seal between the sections of pipe," he said.
"It was a practice that was used 100 years ago. And chances are it's those pipes they are looking at replacing. There are options there. You could line a pipe, which then makes a barrier between the water and the lead.
"But the lead coming from a network is actually quite small. Because these pipes, I know of some that have been in service for 130 years and still don't leak. So, do you change it prematurely or do you spend the money somewhere else? That's part of the trade-off that a water utility is constantly making when they're strapped for resources."
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Roberts said it was unlikely a leak from such a lead join would cause an intermittent spike in test results.
"That's perhaps coming from something else. It all depends, if it's a stagnant piece of water and how the water travels through the network, then you might get an elevated reading there, but it could also be in the source water.
"Of bigger concern, perhaps, is the lead that can be leached out of cheaper brass fittings for tapware. Brass is made in different qualities.
"The more expensive fittings generally have better quality brass, but part of the brass-making process has lead in it, depending on the concentration of lead, so the cheaper fittings tend to have more lead."
Roberts said there were "a lot of ticking time bombs" in water maintenance, like asbestos cement pipes that were used up until the 1970s.
"They were expected to have a lot longer lifespan than what they are. They're finding in the New Zealand environment that they are falling apart prematurely than planned.
"Most water utilities have asbestos cement types. When they're wet they're not a harmful health product. But it just means it doesn't survive as long.
"Timaru, last couple of years their pipes failed early, they had to go and replace their asbestos cement pipes prematurely."
Money was a significant factor behind failing water infrastructure, he said.
"But there are many sources of lead as well. Even those who are on rainwater tanks… If they have lead paint on their roofs, then they are potentially at risk as well."
Other councils would be watching the situation in Waikouaiti and Karitane very closely, Roberts said.
The increase in monitoring comes at a cost, but gives greater understanding of a water network's performance, he said.
"It's only because Dunedin was testing more frequently that it picked up these spurious spikes and they started chasing that."
He suspected there will be increased testing in towns around the country that have cast iron pipes more than 100 years old.
Some councils will be following old guidance and not adapting to new lessons on drinking water infrastructure, Roberts said.
"If you have soft water that dissolves tap brass fittings quickly, [testing] should be done reasonably often. If you have a lot of cast iron networks in your system then you should also be tasting quite frequently… Weekly would be towards the top end."
He said it was hard to say what towns would have such infrastructure, but most that are older than 100 years.
"Without a national database of where all these pipes are, we don't know."
Roberts drinks his tap water but said there are places around New Zealand where he would not.
"There's an annual report the Ministry of Health and ESR do. You can type an address and it will tell you how compliant your water scheme is.
"Some of those have never been compliant in 20 years."
He said a bigger conversation that needed to happen was the level of service people expect form a water and wastewater supply.
"So people [are] not knowing what it is they're paying for and what they're receiving. That would be, I think, a great benefit to New Zealand."