Water Heater Making Noise? Common Sounds & What They Mean
Top TLDR:
A water heater making noise in Polk County is most often caused by sediment buildup — mineral deposits from the region's hard water settle at the tank bottom and produce popping or rumbling sounds during heating cycles. Most noise issues are either a maintenance signal (flush the tank, replace an anode rod) or a pressure-related concern that requires professional diagnosis. Call S&S Waterworks at (863) 362-1119 or book an appointment if the noise is accompanied by leaking, rust-colored water, or a pressure relief valve that keeps opening.
Introduction
A water heater should operate quietly. When yours starts making sounds you have not heard before — popping, rumbling, hissing, banging, or something that resembles a kettle — it is telling you something. The question is whether that something is a minor maintenance signal, a developing component issue, or an urgent safety concern.
Not every noise requires a service call. Some sounds are the normal result of thermal expansion and require no action. Others are early warnings of problems that, addressed now, cost a fraction of what they cost if left alone. A few are signals to act immediately.
This guide covers the most common water heater noises heard in Polk County homes, explains what is causing each one, and tells you directly what to do about it. If you are in Lakeland, Winter Haven, Auburndale, Bartow, or anywhere in Polk County, the local water conditions factor into several of these diagnoses — as noted throughout.
Popping or Rumbling — Sediment Buildup
What it sounds like: A low rumbling or knocking sound during heating cycles, sometimes with occasional popping — similar to the sound of heating a partially full pot of water. The sound typically starts and ends with the heating cycle.
What is causing it: This is the most common water heater noise complaint across Polk County, and it has a straightforward cause: mineral sediment on the tank bottom.
Polk County's water supply carries dissolved calcium and magnesium from the limestone aquifer that underlies central Florida. When that water is heated, those minerals precipitate out and settle at the bottom of the tank. Over time, the sediment layer thickens. Water trapped beneath or within the sediment layer superheats during the heating cycle and forces its way through the deposits — producing the popping and rumbling sounds.
The noise itself is not the primary problem. The primary problem is that the sediment layer is insulating the tank bottom from the water above it, forcing the heating element or burner to run longer and hotter to reach set temperature. This accelerates element burnout, stresses the tank liner, and increases energy consumption. The noise is just the audible symptom of those underlying consequences.
What to do: Flush the tank. Annual flushing removes sediment before it accumulates to the level that causes noise. If the unit is already making this sound, a flush is the first step — though heavily accumulated sediment may require multiple flush cycles to clear fully. S&S Waterworks step-by-step water heater flush guide covers the full process for Polk County homeowners.
When to call a professional: If the noise continues after a thorough flush, or if the tank is over eight years old and has never been serviced, schedule a professional inspection. An S&S Waterworks technician can assess how much sediment remains, check the condition of the heating element, and give you an accurate read on remaining service life. Book online or call (863) 362-1119.
Hissing — Steam, Pressure, or a Leak
What it sounds like: A steady or intermittent hissing sound, sometimes accompanied by a faint whistling. May come from the tank itself, the T&P valve, or the connections at the top of the unit.
What is causing it: Hissing has three distinct sources, each with a different level of urgency.
Condensation: On gas water heaters, hissing can occur when condensation drips onto the burner. This is most common on newer units during the first few weeks of operation and typically resolves on its own as the tank reaches operating temperature consistently. Not a concern.
Temperature and pressure relief valve: If the T&P (temperature and pressure relief) valve is hissing, it is venting pressure — which means either system pressure is elevated above safe levels or the valve itself is failing to seat properly after a pressure event. Either condition warrants immediate attention. A T&P valve that vents repeatedly is not just a nuisance; it is a safety device indicating that pressure management in the system is not working correctly.
A slow leak at a connection: Hissing around the top of the unit near the inlet or outlet fittings, or at the pressure relief valve discharge pipe, can indicate water seeping past a degraded connection seal. In Polk County's humid environment, connections that have been corroding slowly over years can develop this kind of slow weep.
What to do: If the hissing is coming from the T&P valve or any connection point, do not ignore it. Call (863) 362-1119) or contact S&S Waterworks for a same-day assessment. T&P valve issues and connection leaks are straightforward professional repairs — but they escalate quickly if left unaddressed.
Banging or Knocking — Water Hammer or Thermal Expansion
What it sounds like: A sharp bang or series of knocks, often occurring when a valve opens or closes — when the dishwasher kicks in, when the washing machine fills, or when a faucet is shut off quickly. May also occur during the water heater's heating cycle.
What is causing it: Two distinct mechanisms produce banging sounds in water heater systems.
Water hammer is caused by the sudden stoppage of fast-moving water in the supply lines. When a valve closes rapidly, the momentum of the water column has nowhere to go and creates a pressure spike that produces the characteristic bang. Water hammer is a whole-house plumbing issue, not specific to the water heater itself, but it registers most noticeably near the water heater where supply lines are concentrated.
Thermal expansion in a closed plumbing system occurs when heated water expands and has no pathway to relieve that expansion back into the municipal supply. Homes with a pressure-reducing valve, a backflow preventer, or a check valve on the supply line — all common in Polk County construction — are classified as closed systems. Without a functioning thermal expansion tank to absorb that pressure, the expanding water stresses the system and can produce banging or knocking sounds during and after heating cycles.
Florida Plumbing Code requires a thermal expansion tank on closed systems. If your home does not have one installed, or if an existing expansion tank has failed (a waterlogged expansion tank provides no pressure relief), this is both a code issue and a source of stress on every component in the water heater circuit.
What to do: Water hammer can often be addressed with hammer arrestors installed at the supply lines near high-velocity shutoff valves. A failed or absent expansion tank requires professional assessment and installation. S&S Waterworks handles both as part of routine plumbing services across Polk County. If the banging is loud or frequent, schedule an inspection before repeated pressure spikes cause connection failures.
Sizzling or Crackling — Moisture on Heating Elements
What it sounds like: A sizzling, crackling, or frying sound — similar to water hitting a hot pan — during or shortly after a heating cycle. Most common on electric water heaters.
What is causing it: On electric water heaters, sizzling typically means moisture is contacting the lower heating element. This can occur when sediment has built up to the point where the element is partially exposed above the sediment layer and encountering steam and water droplets from the churning below. It can also occur when scale has built up directly on the element surface, creating hot spots where water vaporizes on contact.
Less commonly, sizzling from a gas unit's burner area indicates a condensation issue or a small water leak reaching hot metal.
What to do: On electric units, this sound warrants a flush to remove sediment and, depending on the unit's age and element condition, a heating element inspection. Elements operating at hot-spot temperatures fail sooner than those operating in clean, fully submerged conditions. Schedule a service call if the sizzling persists after flushing — the element may need replacement as part of the service visit.
Ticking — Normal Pipe Expansion
What it sounds like: A light, rhythmic ticking sound from the pipes connected to the water heater, typically when hot water has just been used or when the heating cycle begins. Not a grinding or metallic noise — a soft, intermittent tick.
What is causing it: Pipes expand when heated and contract when they cool. When supply or distribution pipes run through pipe straps, framing holes, or wall penetrations that fit snugly, expansion and contraction cause the pipe to move slightly against those contact points, producing ticking sounds.
What to do: Ticking from pipe expansion is normal and requires no action. If ticking is accompanied by any of the other sounds covered in this guide, address those issues — the ticking alone is not a concern.
Screeching or Whining — Restricted Flow
What it sounds like: A high-pitched whine or screech, usually occurring when hot water is flowing through a fixture connected to the water heater — not during the heating cycle itself, but while you are using hot water.
What is causing it: Screeching during hot water use typically indicates a partially closed or restricted valve somewhere in the hot water supply path. The inlet valve to the water heater — the valve on the cold water supply pipe at the top of the unit — is the most common culprit if it was recently serviced or partially closed. A mineral-restricted flow restrictor or a failing fixture valve can produce similar sounds.
What to do: Check that the cold water inlet valve to the water heater is fully open. If the sound is coming from a specific fixture rather than the water heater itself, the issue is likely at that fixture. If it persists after verifying all valves are fully open, a licensed plumber can diagnose the restriction point quickly. Call (863) 362-1119) or book online.
When Any Noise Warrants an Immediate Call
Regardless of what type of sound your water heater is making, call S&S Waterworks immediately if any noise is accompanied by:
Visible water pooling at the base of the unit — indicates a tank leak or fitting failure
Rust-colored water at hot taps — indicates internal tank corrosion
The T&P valve repeatedly opening and discharging — indicates a pressure management problem
A sulfur or rotten egg smell — on gas units, this can indicate a gas leak; evacuate and call from outside the home
The unit failing to heat water — noise plus loss of function indicates a component failure requiring diagnosis
For any of these situations in Lakeland, Winter Haven, Auburndale, Bartow, or anywhere in Polk County, call (863) 362-1119) or contact S&S Waterworks for same-day service.
Routine Maintenance Prevents Most Water Heater Noises
The majority of water heater noise complaints — particularly the popping and rumbling sounds most common in Polk County — are the direct result of deferred maintenance. Sediment that is flushed annually never reaches the level that produces noise. An anode rod inspected every two to three years never fully depletes, preventing the tank corrosion that leads to rust-colored water and premature failure. An expansion tank that is checked annually and replaced when the bladder fails never allows pressure to build to the point where banging and valve chatter develop.
The full maintenance schedule for storage tank, tankless, and heat pump water heaters — including Polk County-specific intervals for hard water conditions — is detailed in the S&S Waterworks water heater maintenance resources. For commercial water heater maintenance programs across Lakeland and surrounding Polk County communities, see the commercial water heater maintenance schedule.
To schedule annual maintenance or address a noise issue today, call (863) 362-1119) or book online.
Quick Reference: Water Heater Noises
Sound Most Likely Cause Action Popping / rumbling Sediment buildup Flush tank; schedule inspection if persistent Hissing (T&P valve) Elevated pressure or valve failure Call a plumber — do not ignore Hissing (connection) Slow leak at fitting Call a plumber Banging / knocking Water hammer or thermal expansion Inspect expansion tank; consider hammer arrestors Sizzling / crackling Moisture on heating element Flush; inspect element Ticking Normal pipe expansion No action required Screeching / whining Restricted valve or flow Check inlet valve; call if persistent Any noise + leaking Multiple possible failures Call S&S Waterworks immediately Any noise + rust-colored water Tank corrosion Call S&S Waterworks — replacement likely
Bottom TLDR:
A water heater making noise is almost always diagnosable — popping and rumbling point to sediment buildup accelerated by Polk County's hard water, hissing signals pressure or leak issues, and banging typically indicates a water hammer or failed expansion tank. Most of these problems are caught and corrected through annual maintenance before they produce audible symptoms at all. If your Lakeland, Winter Haven, or Bartow water heater is making noise and is more than five years old without a service history, call S&S Waterworks at (863) 362-1119) or book an inspection online today.
S&S Waterworks LLC serves Lakeland, Winter Haven, Auburndale, Bartow, Mulberry, and all of Polk County. Upfront pricing, same-day availability, and a 100% satisfaction guarantee. Call (863) 362-1119 or book online.