There's concern boil water notices are being wrongly used by some water suppliers as long term solutions to water quality issues.

1News can reveal most current boil water notices have been in place more than six months, with the longest in place for a staggering 28 years.

Taumata Arowai took over from the Ministry of Health as the water regulator in November 2021.

The agency's head of regulatory Ray McMillan says they're still getting to the bottom of the term boil water notices.

"The fact that we've got boil water notices that have been in effect for 30 years is really concerning."

Under the Official Information Act 1News has learnt there's 82 current boil water advisories in place, of which 50 are more than six months old.

Twenty-seven boil water notices, or around a third, are more than one year old. And there's 12 that have been in place longer than three years.

McMillan says he isn't happy with how long some of the notices are being used for.

"There's a place for boil water notices. But they are not a tool for suppliers to manage their supply.

"Certainly we'd like to see long term boil water notices disappear."

The longest boil water notice is in Tasman, in a place called Tukurua near Golden Bay. The 100-odd residents have been under the notice since 1994.

The water supply is a stream, there's no water treatment in place and low levels of E-coli is often detected.

In Marlborough around 250 people in Ward have been under a boil water notice since 1995.

Because of poor record keeping Taumata Arowai is still trying to figure out how extensive the water quality issues are. It's possible some of the notices have actually been in place longer than indicated.

"What we're finding out is that the problems are quite complex," McMillan said. "And some of them are long standing. And we've inherited a system which wasn't working particularly well."

Water NZ chief executive Gillian Blythe says the issues are concerning but not surprising.

She says boil water notices should only be a last resort.

"It's a worry, a boil water notice ought to be a temporary measure because you need to find a longer term solution. Because you and I over time can get apathetic. We can forget that that water needs to be boiled."

Many residents and businesses 1News spoke to who live in these areas say they no longer bother to boil their water.

There's tens of thousands of water suppliers and it's often the smaller ones, who supply to a few hundred people, that have issues.

"Smaller providers can often struggle to get the finance together to fix whatever the issue is," Blythe said. "They also might not have the skills to be able to do it, they might not have the knowledge."

In Te Kao, in the Far North, a boil water notice has been in place for many years.

Te Rūnanga Nui o Te Aupouri chief executive Mariameno Kapa-Kingi says the fact the issue remains has left many feeling forgotten.

"So boiling your water and buying your water, where else has to do that? What other communities have to do that?"

"It is a matter of out of sight out of mind. And if you're ignored for that long literally you sort of vanish into the ether and no body knows that it's an issue anymore."

Kapa-Kingi says has helped residents get water tanks and is hoping to soon have a long term solution for the community.