This can be a tank failure with water near gas or electrical parts. If you smell gas or your carbon monoxide alarm is going off, leave the house and call your gas utility or 911 from outside. If the leak is near the electrical connections, do not touch the unit. Shutting off water, gas, or power safely and diagnosing the leak is a job for a licensed technician.
Water Heater Leaking From The Bottom
Three common causes, what is safe to check yourself, and when to call a pro.
The tank itself has failed internally (rust-through)
Pro requiredMost common
Safe to check yourself
- Look at the floor around the base of the tank for standing water
- Check whether the water is coming from underneath the tank itself, not from a pipe or valve above it
A tank that has rusted through cannot be repaired. It needs to be replaced, and a technician needs to shut off water and power safely before that happens.
The drain valve near the base is loose or failing
Pro requiredCommon
Safe to check yourself
- Look directly at the drain valve for dripping, separate from the rest of the tank base
- Feel whether the area right at the valve is wetter than the surrounding floor
Confirming whether it's the valve or the tank without disturbing anything takes a trained eye. Treat any bottom leak as urgent either way and call a plumber.
Condensation, not an actual leak
DIY OKLess common
Safe to check yourself
- Check whether the water heater was installed or the temperature setting was changed in the last day or two
- Check whether the water shows up as small droplets rather than a steady drip or a puddle
If it's droplets only, appeared right after installation or a setting change, and isn't a steady drip, it's usually condensation and clears on its own within a day. If the dripping continues or increases, stop assuming condensation and treat it as a real leak.
DIY or pro, at a glance
- The tank itself has failed internally (rust-through)Pro required
- The drain valve near the base is loose or failingPro required
- Condensation, not an actual leakDIY OK
When more than one cause is possible, start from the most common one above. If you are not sure which cause applies, this one is a pro job.
Not sure if it is worth fixing?
Run the numbers on repair versus replacement cost for your water heater.
See repair or replace costs for a water heaterLast updated 2026-07-03.