Not so, most fire engines can draft from any source of water, Pool, lake.
They use a stiffened hose and a trash screen on the pump inlet and have at it.
That's what I thought. I can remember a fire being put out with water from a nearby swimming pool. With all the standing water I was wondering why they didn't use it even tho I realize it is full of trash. Seems like they could have figured a way around the trash.