Water heaters don’t sing for no reason. Most of the noises they make have specific causes — and some of those causes are urgent. This is a guide to the noises we hear about most often when homeowners call in across our service area.
Popping or Crackling Sounds
Cause: Sediment buildup at the bottom of the tank. As the burner heats the tank floor, water trapped beneath the sediment layer boils, then bubbles up through the sediment producing a popping or crackling sound — like popcorn. Severity: Moderate. The sediment is reducing efficiency and stressing the tank floor, but it isn’t an immediate failure. Fix: Drain and flush the tank — typically a 30-45 minute service call. If the noise has been going on for years, the tank floor may already be stress-cracked and the next failure could be a leak. We assess this on the visit.
Banging or Hammering Sounds
Cause: Water hammer — pressure waves in your plumbing — usually caused by quick-closing valves elsewhere in the house (washing machine, dishwasher, toilet fill valves). The sound originates near the water heater because that’s often where the hammer arrestor is missing or where the pipe transitions from rigid to flexible. Severity: Mid-to-high. Sustained water hammer fatigues pipes and joints over time and can crack copper. Fix: Install hammer arrestors at the offending appliance(s) — typically $150-$300 per location. Sometimes the fix is an expansion tank if the hammer is on the hot side.
High-Pitched Whining or Whistling
Cause: Restricted water flow. Could be a partially closed valve somewhere on the supply line, scale buildup in the heat exchanger (tankless units especially), or a failing pressure-reducing valve. Severity: Low to moderate depending on what’s restricting flow. Fix: Inspect the supply line, descale the heat exchanger if tankless, check the PRV. Most cases resolve with under $200 in service work.
Rumbling or Roaring (Gas Tank)
Cause: Burner combustion issue. Could be sediment-induced overheating, misadjusted burner, or partial blockage in the flue. Severity: High. Combustion problems can produce carbon monoxide or — worst case — flame rollout. Fix: Stop using the unit, schedule service immediately. A burner inspection, clean, and test usually solves it. If the unit is older and has been making this sound for a while, it may be time to replace.
Hissing or Sizzling
Cause: Water on hot surfaces. Either condensation dripping onto the burner (common during high-humidity summer days, usually harmless) or — much worse — a leak from the tank dripping onto the burner. Severity: Variable. Need to inspect to know which one. Fix: Open the access panel, check for moisture and rust around the burner area. If you see water actively dripping or any rust streaking, the tank is leaking. Replace the unit.
Ticking or Tapping
Cause: Thermal expansion of pipes or the tank itself as it heats up and cools down. A check valve in the cold supply can also tick as it cycles. Severity: Low. Mostly cosmetic noise. Fix: Often nothing needed. If the ticking is loud or bothersome, we can sometimes adjust pipe supports or replace a noisy check valve.
When to Call Right Away
Call us immediately for: rumbling/roaring (combustion issue), any noise combined with visible water under the unit (active leak), any noise combined with the smell of gas or unusual exhaust odors, or any noise from a unit that’s over 10 years old that wasn’t there before. Don’t wait — water heaters that start failing tend to fail completely within weeks of the first symptoms.
Hearing something new from your water heater? Sedona Plumbing and Heating dispatches same-day for water heater concerns across Winchester, Arlington, Medford, Lexington, Cambridge, Belmont, Burlington, Newton, Woburn, and 14 other towns. Call (781) 242-2386.
