What’s a dry standpipe? Wikipedia’s got you covered with everything you need to know.

My own summary: “we built fire hoses right into the building so all firefighters need to do is bring water.”

To give you an idea of the relative amountof water required to energize the standpipe: the City of Charlottetown shower head replacement program will give you a new shower head if your current one emits more than 2.5 gallons per minute of water; the standpipe requires 200x that much water, 500 gallons per minute.