Doonbah mushroom growers Matt and Kylie O'Reilly back in business after the 2022 Northern Rivers floods

Three metres of water tore through their property near Evans Head in February 2022, taking their farm and their house as well.

"We had a feeling something would happen but not that quick and certainly not to that magnitude," Mr O'Reilly said.

"We got everything to what we thought was a safe height. We weren't expecting it to enter the upper level of the farm, let alone come close to the house."

The couple endured a terrifying night on February 28 as the water rose around them. They lost power early in the evening and knew that the mushroom farm would be gone.

At 11pm, they were suddenly surrounded by wildlife taking refuge on the verandah. The house sits on a slightly elevated part of the property and it was the only dry place remaining.

As the night went on, the water kept rising.

At 4am they were being rescued, fleeing their home on a boat with just a backpack and their dog, Zug.

The disaster was something the O'Reillys could never have imagined when they embarked on their new life as mushroom farmers.

Originally from Moree, they'd been living overseas for 16 years for Mr O'Reilly's work as a commodity trader, when they decided it was time to come home to be closer to family.

They also wanted to run their own business: "Matt and I had worked for other people all of our lives and we just made that decision that we wanted to work for ourselves," Mrs O'Reilly said.

They initially had their minds set on oyster farming and researched it extensively while overseas.

But then a business broker asked them if they knew the Northern Rivers - "and we did, because Matt's family are from Maclean and Ballina and we both studied uni at Lismore," Mrs O'Reilly said.

The well-established mushroom farm they purchased, Richmond Mushrooms, was just seven kilometres from the coast at Evans Head.

"We were looking for a balance of work and lifestyle," Mrs O'Reilly said.

"When we saw the block of land I said to Matt 'if this business works I could definitely live here.'"

They bought the farm as a going concern and then spent the first 12 months doing maintenance and bringing it back up to spec.

Once that was complete, they were looking at increasing production by 30-40 per cent and adding Swiss Browns to the range.

But all that came to an abrupt stop with the flood.

It took almost a week for the floodwater to recede and when it did it revealed what Mr O'Reilly describes as an 'environmental disaster.'

"The (11) grow rooms were all cold room panelled and...essentially they all just lifted up with the flood...and just imploded on each other and collapsed.

"And beneath that was all the mushrooms and mushroom compost and all the racks.

"It was just a horrible garbled mess."

The scale of the disaster made it difficult to access resources, but friends and family stepped in, bringing trucks and excavators and bobcats and then running countless truckloads of the former farm to the tip.

"Then In the last week of the clean up, Richmond Valley Council were able to allocate us some larger excavators and three trucks," Mr O'Reilly said.

"We went 21 days straight demolishing the farm.

"It was enormous."

Once the clean up was done, the O'Reillys moved into a caravan, gutted their house and hired two builders to help them get the house livable again, which took about four months.

By then, they'd decided they wanted to stay in mushrooms, but couldn't find anyone willing to rebuild the farm to the size they wanted.

They turned to other growers for advice and eventually found someone who helped them see a way forward.

"We managed to form a relationship with a mushroom farmer just south of Eumundi.

"He grows in traditional rooms like we had but he also grows in shipping containers."

It was the perfect solution for the O'Reillys.

"It was a much more cost effective method for us to get back into it and much quicker as well," Mr O'Reilly said.

"You have the added benefit that if it floods you can open the doors and wash it out at the end of the flood. They're also not going to collapse, and they're fireproof."

Eventually the O'Reillys were able to set up six 40-foot reefers (refrigerated shipping containers) and in August - 18 months after the flood - started producing mushrooms again.

They're now growing about one-and-half to two tonnes of mushrooms a week, roughly half their production pre-flood.

The shipping containers have cut their costs significantly.

"The thermal properties of the containers are exceptional," Mr O'Reilly said.

"Previously we required 15-16 KW to cool one room - that's roughly a $15,000 to $16,000 air conditioner.

"We've dropped down to a quarter of that and we're on half the production we used to be.

"So that's a significant reduction in the capital outlay on the air conditioning units."

And while electricity prices have increased since the flood, their power bill is 50-70 per cent less.

They continue to grow Agaricus bisporus (which produce buttons, flats and field mushrooms) and use a six week cycle for the compost the mushrooms grow in.

"Every week on Monday we empty a room and sell the compost," Mr O'Reilly said.

"We clean and sterilise the room and on Tuesday a fresh load of compost (inoculated with mushroom spores) arrives.

"We put it in the room and start the whole process again."

They also swapped compost providers and are achieving a better yield.

"We're getting 15 to 25 per cent more yield off a reduced compost base."

Mr O'Reilly says while it was inevitable they would lose some market share after being out of action for so long, they had received fantastic support from most of their customers in the area they service from Yamba to Tweed Heads, including Coles.

"All of the local guys we were with were immediately back on board," he said.

With the help of social media, the O'Reillys have also managed to pick up some new customers since the flood, including Three Blue Ducks at The Farm in Byron Bay.

"We've had a number of chefs starting to follow us and wanting to use local produce rather than (Brisbane) market produce," Mrs O'Reilly said.

"It's a bit more logistics for them but they like the produce and the fact it's local."

Although mushrooms can seem tricky to grow with their quite specific requirements for moisture, carbon dioxide, humidity and temperature, their short life cycle actually makes them quite forgiving, according to Mr O'Reilly.

"It's not like an oyster that takes three years to grow and then something goes wrong, or a wheat crop that's been six months developing and gets wiped out by a hail storm.

"Here, every week you get a chance to correct what you did wrong in the previous week or repeat what you did the previous week if you got it right.

"You get three harvests out of each room before you terminate and get rid of the compost so if something goes wrong on the first week you tend to pick it up on the second or third."

It's still early days, but the O'Reilly's say that when things have stabilised in six months or so, they'll look at expanding if the demand is there.

They'd still also eventually like to add Swiss Browns to the mix.

And while it's been a long difficult road, they love where they live and aren't about to give up the mushroom farm anytime soon.

"Like any farming you have ups and downs," Mr O'Reilly said.

"It's pretty rewarding at the end of the day.

"It's a lovely place and we're very happy to be home and put roots down."