Helene Ritchie, who has spent 30 years as a councillor, opposes a cap on local body politicians' length of service.

New Zealand's longest-serving councillor is on track to notch up half a century in public office – provided voters give him the tick once again this year.

Grey District Council deputy mayor Doug Truman, 76, was first elected to a local authority in 1968, and plans to run for another three-year term in October's local body elections.

His 48 years in office to date make him by far the country's longest-serving councillor, according to information compiled by the Taxpayers' Union.

Grey District Council deputy mayor Doug Truman, who has been a councillor for 48 years.

Only a handful of politicians around the country have served 30 or more years on councils. Those to clock up three decades include Wellingtonians Diane Ammundsen (Kapiti Coast), John Burke (Porirua), Margaret Cousins (Lower Hutt) and Helene Ritchie (Wellington).

Truman, a Greymouth bookstore owner, said he was surprised to learn he was the country's longest-serving councillor.

As a retailer in a small town, it was natural to become involved in community service roles, and it was important for people with broad local experience to be involved in governing their communities, he said.

At 76, he would be putting his name forward for this year's elections.

"Democracy is a funny thing – they [the voters] might say I'm too long in the tooth, or I might still have a loyal following. When you get older, of course, a lot of your loyal following has left the planet."

Taxpayers' Union researcher Matthew Rhodes said the figures showed turnover at councils varied greatly. The longest-serving councillor on Westland District Council had been there for only seven years.

"Whilst we all recognise the need for organisations to have long-standing personnel with institutional knowledge, we think these figures suggest that it is timely to look at implementing term limits at local councils.

"If you've been on a council for six terms – 18 years – and you haven't yet achieved what you set out to, it seems unlikely that you will do it by staying on council for another 18 years."

That view was not supported by Ritchie, who has spent 30 of the past 40 years as a councillor in Wellington.

Councils were "very dynamic entities", so it was important to have experienced councillors at the helm, she said.

"It is essential to have good, sound, active experience in governance and in council affairs. Nothing beats that."

Local Government New Zealand president Lawrence Yule, himself a 21-year council veteran, said the organisation had no official view on term limits for elected representatives, and there were "arguments both ways".

"Some would argue that term limits allow new people to get on to councils. Equally, people get elected and stay on councils by democratic decision-making of people. Those that have been there a long time are supported by the majority of voters."

LONGEST-SERVING COUNCILLORS

Wellington City Council – Helene Ritchie (30 years)

Kapiti Coast District Council – Diane Ammundsen (30 years)

Porirua City Council – John Burke (30 years)

Hutt City Council – Margaret Cousins (30 years)

Hastings District Council – Lawrence Yule, Cynthia Bowers (21 years)

Greater Wellington Regional Council – Chris Laidlaw, Sandra Greig (18 years)

Napier City Council – Mark Herbert (18 years)

Hawke's Bay Regional Council – Christine Scott (15 years)

Upper Hutt City Council – John Gwilliam (12 years)