In a disaster, you find heroes in the most unlikely places.

As 80,000 people abandoned Fort McMurray earlier this week, George Muirhead stayed behind to man his post.

With a raging wildfire already burning homes and the city under a mandatory evacuation order, Muirhead packed his vehicle.

Then he made his way to the water treatment plant near the Athabasca River.

Many of the plant's employees had already fled with their families, leaving a skeleton crew of nine men to continue their vital work, providing the water firefighters so desperately needed as they fought to save the city.

Muirhead, a utility treatment technician, worked around the clock until Wednesday afternoon, when flames began to threaten the plant itself.

For a time, the crew was forced to evacuate to an oilsands camp north of the city. But hours later, under police escort, they returned to the plant.

The fire and smoke from the Fort McMurray can be seen from the water treatment plant as the blaze makes it way through the town on Tuesday night. (Supplied) What Muirhead saw there reminded him why they couldn't leave, no matter how close the fire came.

"The fire had come to the water plant, burned the hillside just across from us, and had burned all around the perimeter of the water treatment plant itself," Muirhead said.

"And for some reason, some way, it decided to not hit our river intake structure, where we pull the water in from the river."

At one point, the firefighters who saved the plant sat on the tailgate of their fire truck, completely exhausted.

"You could tell they had worked tirelessly to do what they can to mitigate the fire around that plant and save it," Muirhead said. "And then we come in immediately after to try to keep the water going for them."

Exhausted workers keep reservoirs full

Even as trees burned 50 feet from their control room window, and the entire plant filled with thick smoke, the nine workers continued to do their jobs. They wore dust masks, only removing them in the control room, which has an air purifier.

The work is technical and requires critical thinking, Muirhead said. But thinking two, three, 10 or 20 steps ahead became nearly impossible, given they could grab just an hour or two of sleep over long stretches of time.

We know keeping the water going is important for the firefighters, and we're there for them as much as they're here for us. - George Muirhead , water treatment plant operator

Keeping water reservoirs full in every area of the city is impossible, he said, especially in hard-hit areas like Abasand and Beacon Hill.

"We are called essential services. I can't speak for all of us, or all people in the water industry, but we kind of take that to heart," Muirhead said.

"We care, and it's hard to stop caring. We know keeping the water going is important for the firefighters, and we're there for them as much as they're here for us."

The crew lost control of some water facilities at the main plant and had to drive through the city to run equipment manually. They drove past burning buildings in Beacon Hill and Abasand as embers fell around them, he said.

'Nobody's trying to be a hero'

Muirhead finally left Fort McMurray for Red Deer two days ago. Five operators remain at the plant, alongside two foremen and the plant manager, he said.

On Friday, Calgary announced it would send three water treatment operators and one process engineer to help the remaining crew.

Muirhead has been logging into the plant's computer system remotely to help with operations. He's monitoring the plant from afar and lending support over the phone to those who remain there.

He can still tell how much water is being pushed out the distribution system to fill reservoirs and pumps, and sees data coming back in. He knows which parts of the system remain operational.

Nonetheless he said he feels bad about leaving his team, even though personal reasons forced him out.

A child's bike rests in front of a burned out home. (Tyler Hicks/The New York Times) He's still haunted by what he saw in the smoldering neighbourhoods.

Like the child's bike that, somehow, remained mostly intact while everything else burned to rubble around it — a glimpse of the life that once filled the city and the long rebuild ahead.

"Nobody's trying to be a hero," Muirhead said. "If we can ... keep that water going for those firefighters, save those houses, those treasured moments, treasured memories for those people ... they can come back to those homes and their children's stuff is still all there.

"We need water, the city needs water, the firefighters need water. We've got to keep it going. As long as we can."