Plumbing in Pittsburgh has to live on a slope. The lower level may sit below the street, so a drain that works on flat ground needs a pump here. Laterals run downhill. The uphill foundation takes groundwater, and a floor drain in that lower level is a different emergency from a kitchen faucet. Freeze still hits exposed downhill walls and hose bibs. Older galvanized lines and a water heater in a damp basement are ordinary. Say if water is moving and if the main is somewhere you can reach.
Separate the calls. A burst supply line is a shutoff problem first. A backup at the walk-out during rain may be groundwater, a sump, or the lateral, not a clog in the trap. A water heater that quit or is leaking is the third job. If the heater is in the lower level that floods, say that before anything else about the tank. If heat is also out, frozen lines and the heating plant are racing. Say both.
You can make the story specific without opening walls. Which wall faces uphill. Whether the lower level is wet only after rain. Whether a hose bib on the exposed side was left charged. Whether the sump runs constantly or has stopped while the floor gets wet. Those four facts pick the trade's next move. Do not treat this like a flat row where the only vertical is a stack inside the house. You may have that stack too. The hill is the extra.
Have tank or tankless, gas or electric, if the heater is the subject. Say if a drain was cleared and the backup came back with the next storm. That pattern points outside the house. Ask about the vent, the pan, and a pump if fixtures sit low. A cable clears a clog. It does not rebuild a lateral down a hill or stop groundwater. Say which mess is in front of you.
Slope plumbing is pumps, buried walls, and freeze on the open side. Plumbing in Pittsburgh starts with where the house sits relative to the street. Call the number on this page.