Voter turnout for this Saturday's local elections is heading for a record low, with an official saying online voting must be brought in to halt the decline.

Electionsnz.com chief returning officer Warwick Lampp says turnout has been trending down for some time.

He says based on current estimates, turnout this election is likely to be at an all-time low.

In 2016, turnout was 42 per cent, but Warwick says this time it's unlikely to get above 40 per cent.

He says online voting is critical to halt that decline.

"[It's time] for central and local government to get their heads together and nut out an online voting system.

"The impetus is there, the desire is there - people are wanting it - and I think we just need to get our heads together and get it sorted."

A group of councils had tried to get a trial of online voting up and running for this election, but were forced to drop it late last year due to the cost.

Group spokesperson Marguerite Delbet says they haven't given up hope.

They are eyeing the 2022 elections, and want the government to partner with them to make it happen.

"The first thing is to get the regulations in place. We've got legislation [in place but not] the regulations, and some clear parameters for whether we can trial online voting for any byelections that might happen between 2019 and 2022.

"And whether the government is ready to come to the party to help financially."

A Department of Internal Affairs spokesperson says the Justice Select Committee was considering public submissions it received on its inquiry into the 2017 general election and the 2016 local government elections, and would make recommendations in due course.

Today is the last day of postal voting but people can drop their ballot paper at council service centres, libraries and community centres until midday on Saturday.