New water heater leaking from the bottom
Call the installer — do not buy another heater
A new tank has not corroded. Steel takes years to rust through, so water under a heater fitted this year is almost never tank failure. It is an install fault, first-heat condensation, or a manufacturing defect — and all three are somebody else's bill.
How to tell it's this
- The unit was fitted in the last few months.
- The water is clear rather than rusty.
- It appeared within days of install, or the first time the heater ran a full cycle.
- On a gas unit, it showed up during the first heat-up and then eased off.
What to do
- Call the installer first. Do not let anyone sell you a replacement heater for this.
- Check the drain valve at the bottom. A drain valve that was not fully closed after filling is the single most common cause, and it is a two-second fix.
- Look at the T&P discharge pipe running down the side. If it is wet, the water came from the relief valve and ran to the floor, and the tank is fine.
- Keep the invoice and the paperwork. Tanks carry 6–12 year manufacturer warranties, and a defective new tank is replaced under it.
What it costs
Expect to pay nothing. Between the installation warranty and the 6–12 year manufacturer warranty, a genuine fault on a heater this new is covered.
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
The heater is more than about 8 years old
A tank that has rusted through →
It is the relief valve dripping on a new unit
New heater, relief valve leaking →
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.