Slow leak from the bottom of a water heater
Find the source — slow does not mean minor
Speed is a real diagnostic. A slow drip you can trace to a fitting is a repair. A slow seep with no traceable source, that always comes back, is usually the tank starting to fail — and a tank that seeps today floods later.
A slow leak still means standing water near gas or electricity. Keep the area dry and cut the power or gas if water reaches wiring or the burner.
How to tell it's this
- Repair: you can follow the water to the drain valve, a connection, or the T&P discharge pipe.
- Repair: it stops entirely when you shut the cold water off.
- Tank: a damp ring under the base with no wet fitting anywhere above it.
- Tank: rusty staining on the floor or the base skirt, and the unit is past about 8 years.
What to do
- Dry everything and lay paper towel around the whole base and under each fitting.
- Leave it two hours without drawing hot water.
- Read where the paper wets first. That is your source — it beats guessing every time.
- If the wet paper is under the tank body with dry fittings, plan for a replacement rather than a repair. Do not wait for it to get worse.
What it costs
A traced fitting is roughly $150–$400 fitted. A seeping tank is a replacement — about $700–$1,800 for electric and $1,000–$3,000 for gas, installed.
Typical US ranges for 2026, not quotes. Labour is 30–50% of an installed price, so where you live moves these numbers more than anything else does. Get two or three local estimates.
If that's not it
You traced it to the spigot near the floor
The drain valve →
It only appears while the heater is running
Water only when heating →
Not sure which of these it is?
Answer four questions — where it's leaking, tank or tankless, gas or electric, and how
old it is — for a specific cause, a repair-or-replace call, and a cost.