Potomac — While more summer-like temperatures over the weekend might have obscured the memory, last Friday, April 13, was a chilly day, in the 50s, with a significant breeze. So it was clear that firefighters in front of Cabin John Volunteer Fire Department Station 30 on Falls Road were not filling a pool to cool off.

The large red portable water container is part of the county's "rural water supply," along with the county's seven tanker trucks, to serve areas of the county that do not have fire hydrants.

"We have some pretty significant homes in the Potomac area," that are outside the hydrant area, said Scott Graham, county fire public information officer. The rural water supply protocol calls for a 3500-gallon tanker to arrive at the scene of the fire along with a 750 gallon fire truck, providing sufficient water to launch a first attack on the fire.

Meanwhile, a supply pool, like the red one shown in these photos is set up, and one or more additional tanker trucks will establish a fill-and-dump loop between the fire and the closest water supply. This could be a fire hydrant, or a swimming pool, or a pond, lake or creek.

County firefighters use this system to fight at least a fire a week.

About two weeks ago, a fire on Esworthy Road in Potomac required a rural water supply, as a garage with living quarters caught fire near a house of significant size, Graham said.

— Mary Kimm