A leaking water heater
There are two failures here and they share almost nothing. A slow bead at a threaded connection is a repair you can book. A tank that has rusted through is a flood that refills itself, forty to eighty gallons at a time, until somebody closes a valve.
- 1 The ceiling stain. It measures the ceiling, not the leak. Water travels along a joist before it drops.
- 2 A burst supply line. Pressurized, so it runs until somebody closes a valve, and it runs downward.
- 3 A frozen line. The exterior wall is where the pipe meets the cold, and where it splits.
- 4 The washer hose. Rubber under constant pressure, and a standpipe that overflows quietly.
- 5 The water heater. It goes at the bottom of the tank, usually while the house is empty.
- 6 Groundwater and backup. Water pressing on the wall, and a floor drain that reverses when the combined sewer fills.
First: stop the supply and the heat
Start with the cold inlet valve at the top of the tank. Corroded gate valves in older Baltimore basements often refuse to turn: if yours does, go straight to the main rather than forcing it. Then kill the energy: the breaker on an electric unit, and on a gas unit the control knob turned to OFF, which is not the same thing as turning the temperature down.
A tank that fires with no water in it destroys itself, and on an electric heater the elements can be gone before you have finished mopping.
Where the water is coming from
Trace it upward and the answer is usually obvious. Wet at a threaded joint or a union: a connection, and a repair. Wet at the relief valve or running from the discharge tube to the floor: the tank is venting pressure, which is a symptom of something upstream rather than a fault in itself. But water appearing at the base of the jacket with nothing above it to blame means the steel has corroded through, and a perforated tank is replaced, never patched.
What it does to a finished basement
Most water heaters in this part of Maryland sit in a basement, frequently in a utility area adjacent to finished space. A tank failure sends clean water across a floor at volume, and it moves under baseboard and into carpet padding faster than it can be mopped. The water itself is not contaminated, but the assemblies it soaks, padding, subfloor, the bottom plate of a stud wall, hold moisture long after the surface looks dry.
How much of that has to come out depends on the room it happened in. A utility cellar is one conversation; a finished lower level of the kind common through Columbia and Randallstown is another, because the trim, the insulation and the bottom plate all have to be judged separately rather than swept into a single line.