With a large land area and a small population, the cost of looking after the environment was too great for people of Wairarapa to bear alone, he said.
"It's an unreasonable burden on those people to be able to adequately look after, or pay for, the very large environmental impacts that are coming."
Mr Rangi said the district was not as rural as people often liked to claim, with 84 per cent of Wairarapa's population being urban-dwellers.
Commissioner Anne Carter questioned Mr Rangi's definition of "urban", pointing out Holloway St was hardly comparable with Lambton Quay.
When asked by commissioner Basil Morrison if he could see a unitary authority supported by the regional council as a viable position, Mr Rangi said he could see it as an "excellent position".
Meanwhile, members of the South Wairarapa District Council Maori Standing Committee spoke strongly against the draft proposal at the hearing yesterday.
Addressing the commissioners from a table adorned with the United Tribes flag, the flag chosen for New Zealand by a gathering of Maori chiefs at Waitangi in 1834, committee chairman Michael Roera said they did not want to lose their close contact with councillors.
"There's no way that we can have a personal touch if Greater Wellington takes over and we have to be running over and making toll calls just to stop someone dumping bitumen down at Te Ore Ore Rd - that wouldn't suit us."
The proposal would also represent a shift in traditional iwi boundaries, Mr Roera said.
Deputy chairman Johni Rutene said they had not be consulted and did not consent to the proposal.
"To govern the people, you have to have consent and we don't consent to you guys. We will not stand and let another river extraction happen from the decisions made by a central Wellington regional council - we have had enough of our eels being killed by decisions made by someone else.
"Our whenua is hurting, our rivers are dying and our people are hurting. Why? Because the mana has been taken away from the Maori mana whenua. We are not going to stand by this anymore, we have had enough."
A member of the Martinborough Community Board, Lisa Cornelissen, also spoke against the proposal, saying the board feared local knowledge would be lost.
"I don't believe that a single councillor sitting on a Masterton-centric board will be able to represent Martinborough community to the extent that we can."
This week's final Wairarapa hearing starts at 9am today at the Copthorne Hotel in Masterton.