Water heater leaking from the cold water inlet
Likely a repair
This is a fitting, not the tank. The cold inlet is the right-hand pipe on most units, cool to the touch, and it usually carries the shutoff valve. The leak is the valve packing, the flexible connector, or the nipple.
How to tell it's this
- The wet pipe is cold and carries the shutoff handle.
- It keeps leaking even with the heater switched off — the cold side is under street pressure all the time.
- Water runs down the outside of the tank from that one joint.
- The drip worsens when you operate the shutoff valve.
What to do
- Turn off the home's main water valve, not just the heater's shutoff — the leaking valve may be the thing that will not close.
- Dry the joint and watch which of the three points weeps: the valve stem, the connector nut, or the nipple thread.
- A weeping valve stem sometimes stops with a quarter-turn on the packing nut. A leaking connector needs replacing.
- Have a plumber replace a failed shutoff. It is a cheap part and it is the valve you will need working the next time anything goes wrong.
What it costs
With a plumber
Reseal or replace the leaking connector
$150–$400
installed
Part only
If a pro is already on site
$10–$50
the part itself
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 wet pipe is hot, on the other side
The hot outlet is leaking →
The leak is at the valve with a pipe running down the side
The T&P relief valve →
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.