One man was taken to the hospital as a precaution - he is expected to be okay.
Fire officials said they responded to the fire on Finson road just before nine Saturday morning.
They said heavy fire was coming out the back part of the building when crews first arrived.
The building belongs to "Fleming Water Systems and Water Treatment" and is a total loss.
Firefighters said they were able to get the fire under control in minutes, but did need to call in more help.
The assistant fire chief of Bangor Anthony Riitano said, "It is outside the hydrant district so we did have our tanker and we did call two other tankers as a precaution, but we were able to knock it down and put the fire out with our tanker full of water."
One employee for the small business said they will continue operation, but they'll have to restock.
The cause of the fire is still under investigation.