Plumbing in Washington is the stack of a District rowhouse, old, vertical, and unforgiving. Galvanized supply and cast-iron waste still serve many kitchens and baths. The top floor may have weak pressure while the basement has plenty. A wet kitchen ceiling is often the bath overhead, and it is sometimes the flat roof pretending to be a pipe. Say what you think and why, and say the floor.
The main shutoff is usually low in the house and may not have been turned in years. Alley hose bibs freeze when the indoor valve stays open. Water rising from a basement drain in a storm is a different emergency from a burst line at the ell. A bath in the English basement often relies on a pump. If that pump failed, lead with it. Seized valves are common enough to mention before someone assumes they can shut the house down quickly.
Water heaters sit in closets and cellars that are also living space. Say gas or electric, leaked or cold. A relief line into a floor drain can be ignored until the tank is already done. Several fixtures gurgling together point at the building drain. One slow sink points at a branch. Old laterals under these streets settle. You do not have to solve that. You have to describe how many fixtures are involved.
Additions and basement baths sometimes created runs the original stack did not expect. If the only cleanout is buried in a finished floor, say so. You do not need a catalog of metals. You need the wet spot and the ability, or not, to shut the water off. Shared-wall noise when a neighbor runs a faucet is not, by itself, your leak.
Say what is wet. Plumbing in Washington is old stacks in narrow District chases, alley freezes, and English basements that take storm water. Call the number on this page.