Boiler Leaking Water: What to Do Right Now
Last updated Reviewed by Waseem Shahzad, Lead Technician
A leaking boiler can lose pressure and heat, and water near wiring is a safety concern. Turn the boiler off at its service switch if water is reaching the burner or controls, move valuables away, and note where the water is coming from. Then call (631) 414-7141. K2 answers 24/7 from Deer Park.
Call 24/7: (631) 414-7141Smell gas or hear a carbon monoxide alarm? Leave the house first, then call 911 or the gas utility from outside.
What should you do right now?
If water is spraying, pooling near electrical parts or coming from the boiler body, turn the boiler off at its service switch. Put a bucket under a drip and move anything that could be damaged. Read the pressure gauge. Do not open the boiler or tighten fittings on a hot system.
- Power: service switch off if water is near the burner, controls or wiring.
- Contain it: bucket or towels under the drip.
- Look: note whether it comes from the relief valve pipe, a fitting, an air vent, the circulator or the boiler body.
- Gauge: note the pressure; it tells the technician a lot.
Why is my boiler leaking?
The most common causes are a failed expansion tank that pushes the relief valve open, a leaking air vent or bleeder, a worn circulator gasket, a loose or corroded fitting, or a failing relief valve. Water from the boiler body itself can mean a cracked section or heat exchanger.
In our records, a Hauppauge boiler leaked because of a bad expansion tank and air vent, and another home in Dix Hills needed an expansion tank and air bleeder; see the Dix Hills boiler leak repair. In Woodbury we replaced an expansion tank, relief valve and air bleeder together.
Is water from the relief valve an emergency?
It is a warning to act on. The relief valve opens when pressure or temperature gets too high, often because the expansion tank failed or the boiler overfilled. It is protecting the boiler. Never cap or plug it. If it keeps discharging, turn the boiler off and call.
Our boiler pressure guide explains what the gauge should read and why pressure climbs. A relief valve that drips at normal pressure may simply be worn and need replacing.
What does K2 do on a leaking boiler call?
We find the source, check the pressure and the expansion tank, and test the relief valve. Then we quote the repair, replace the failed part, refill and bleed the system and confirm the pressure holds while the boiler runs. If the boiler body is leaking, we talk about replacement.
See boiler repair and emergency gas boiler repair. If the house is cold while you wait, see frozen heating pipes for how to protect the plumbing.
Recent no-heat calls we fixed
Leaking boiler: expansion tank and air bleeder replaced, plus a tune-up
Dix Hills · Boiler Repair · March 2026
A leaking boiler. We replaced the expansion tank and the air bleeder, bled the air from the system and did the yearly boiler maintenance.
Expansion tank, relief valve and air bleeder replaced
Woodbury · Boiler Repair · October 2025
During a fall maintenance visit, the technician found a worn expansion tank, relief valve and air bleeder. All three were replaced on a return visit.
Questions people ask
Can I keep using a leaking boiler?
A slow drip from a fitting can usually wait for a scheduled repair if pressure stays normal. A leak from the relief valve, the boiler body, or anything near wiring should not. Turn it off and call.
Why does my boiler pressure keep dropping?
A leak somewhere in the system, sometimes hidden under a floor or inside a baseboard, or a relief valve that releases water when pressure spikes. Topping it up only masks the problem until the source is fixed.
Does a leaking boiler need to be replaced?
Usually not. Most leaks come from replaceable parts such as the expansion tank, relief valve, air vents or circulator gaskets. A leak from a cracked section or heat exchanger is the main reason to replace.
Need help now?
K2 answers 24/7 for homes within 15 miles of our shop at 60 S 2nd St, Unit V, Deer Park. You get a time window and the price before any repair.
Call 24/7: (631) 414-7141