Rural Fire Service (RFS) operational teams have sought advice from Victorian fire authorities and commenced discussions with Port Macquarie-Hastings Council about the feasibility of the plan.

The proposal includes building a two-and-a-half kilometre pipeline to channel reclaimed water from the Hastings network on to the fire zone.

If given the green light, it could take up to 30 million litres of water and eight weeks to bring the fire to an end.

The bushfire has burnt an area of 420 hectares west of Port Macquarie since it started on July 19. RFS and Fire and Rescue NSW crews have worked together to contain the blaze which is being fueled by underground decaying vegetation and organic peat material.

NSW RFS district operational officer Steve Farrell said the underground material has dried due to drought-like conditions and become highly flammable.

"That organic material and vegetation has accumulated over decades or centuries as a coastal wetland," he said.

"In this case, it has dried out enough to support a sub-surface fire which moves before popping up in an unburnt area .

"This is more dangerous for firefighters because there's no way of knowing that five or 10 centimetres below the blackened surface there could be a cavern of glowing combustion of 400 or 500 degrees."

Due to the difficult nature of the fire and terrain, the Large Air Tanker (LAT) Marie Bashir was used to water bomb a flare-up ahead of windy conditions on August 8, and again yesterday (August 22).

Mr Farrell says there is now a multi-agency plan to rehydrate hectares of burning peat underground, which water bombers cannot reach.

"We have a proposal to lay two-and-a-half kilometres of piping from a reclaimed water point," he said.

"We are working with Port Macquarie-Hastings Council on that. They have a local plant so we have had to work with its commercial customers to balance production and provide us with what we think we need.

"We're estimating at this stage something in the order of 25 to 30 million litres. Rehydration could take six to eight weeks.

"It's a multi-agency decision and it's a multi-agency effort that requires funding as well."

Saltwater from the nearby Hastings River cannot be used because its salinity would disrupt the acidity of the environment, according to Mr Farrell.

Fire retardant cannot be used in the area because of the sensitive habitat and high smoulder ranking of peat.

"The only other way it will go out is if it burns all the material, or a massive rehydration event such as a flood or massive rain event occurs," he said.

"We know that there is no foreseeable rain event until November and there are other examples of peat fires in Indonesia which have burnt for nine months.

"One of the risks we face with this is the prolonged dryness could also have extended to a base earth layer of clay. If it's cracked, we could literally be pouring water into an endless crack in the earth."

A similar four kilometre above-ground pipeline was used by Victorian firefighters to extinguish the Cobrico peat fire in April 2018.

RFS district officer Stuart Robb said the bushfire is more complicated than a regular bushfire.

"The extinguishing of the peat fire is our ultimate goal," he said.

"We may need to re-hydrate this area and we have to test if the water will remain in that area and not seep out.

"We have been in contact with some specialists from the Country Fire Authority in Victoria who have dealt with a number of large peat fires down there."

Port Macquarie MP Leslie Williams is looking for a solution as well. She spoke with Acting Rural Fire Service Commissioner Rob Rogers about the fire on August 22.

"I commend the tireless efforts of the Rural Fire Service volunteers and appreciate they are doing everything possible to contain and extinguish the fires," Mrs Williams said.

Health warnings have been issued by the North Coast Public Health Unit due to the thick, odorous and irritating smoke produced by the incomplete burning of peat.

Residents can reduce the affects of the peat smoke by staying indoors, using an air conditioner to recirculate inside air and limiting physical activity.

Dust masks designed to filter fine particles may also assist in reducing the amount of smoke particles a person is exposed to.

The Bureau of Meteorology has predicted windy conditions this weekend.

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