A large part of the area supported by North Hays County Fire Rescue is rural so firefighters can’t be sure of having hydrants close to any emergency. To handle this, they deploy what looks like a huge, collapsible paddling pool at the site then have tankers shuttle back and forward from the closest hydrant refilling this reservoir as the firefighters work. The high diameter hoses you see here are used to suck water from the reservoir into the truck where it is distributed to the hoses being used by the firefighters.
For the technically inclined...