Plumbing in Pennsylvania is old in both big cities and simply arranged differently. A Philadelphia row stacks baths on a chase, and a wet ceiling is often the fixture above or a flat-roof leader tied into the drains. A Pittsburgh hill house puts the basement below the street on one side, so a sewer lateral runs downhill and a pump is a normal question. Philadelphia rowhouses are not Pittsburgh houses on hills. Freeze on an outside wall still happens in both, and in the detached towns between them.
Open with leak, drain, or water heater. A supply leak needs a shutoff, which in a row may be in a basement you reach from the stoop and on a hill may be in a cellar that is already wet. A slow tub is not a backup at the lowest floor during a hard rain. A water heater in a narrow row basement is not the same replacement as a heater in a walk-out lower level. Say what you see and whether water is still moving.
Rain exposes the difference. Rows with flat roofs can send storm water into pipes you thought were only for the kitchen. Hill houses take groundwater at the uphill wall and sometimes a floor drain that cannot keep up. If the trouble starts only when the sky opens, say that. It splits a roof or groundwater problem from a broken supply line. Galvanized pipe and stiff valves are common in the older stock. Do not twist every old stop to see what happens.
Have the heater type if that is the complaint: tank or tankless, gas or electric, hot water or an active leak. Say if a drain was cleared and returned. Say who lives below a row bath. Ask about the vent, the pan, and whether a pump is part of a basement bath. A cable clears a clog. It does not repair a lateral running down a hill or a stack that has rusted through. Point at the failure you can see.
Stacked row plumbing and a hill lateral are different calls. Plumbing in Pennsylvania starts when you say which house and where the water is. Call the number on this page.