Noisy Water Heater
Popping, Hissing & Humming Causes (2026)

Should a water heater make noise at all?

Some noise is normal. An electric heater switches its element on and off through a thermostat, water moves and expands as it heats, and pump models have a motor. A quiet click when the heater starts, a soft hum while a pump runs, or a little ticking from the pipes afterwards is no cause for concern. What matters is a new noise, a noise that is getting louder, or a noise that comes with a leak, a smell or a tripping switch.

Which heater you have changes the list of likely causes. A storage heater keeps a tank of water hot; an instant heater heats water as it flows; a pump model adds a small booster pump. Our water heater types guide explains the differences.

Sound by sound: what it usually means

Popping and crackling: scale on the element

Hard water and sediment leave a crust on the heating element and the bottom of a storage tank. Small pockets of water trapped under that crust overheat and burst into steam, which you hear as popping, crackling or a kettle-like rumble while the heater is working. ClickBina's storage heater parts guide notes that scale build-up on the element makes it work harder and heat more slowly, and that this is common where the supply carries sediment. The cure is cleaning or flushing the tank and, if the element is badly scaled or has failed, replacing it. In an instant heater, scale in the heating chamber can cause a similar crackle.

Rusty or smelly hot water alongside the noise points to a used-up anode rod in a storage tank, which is worth checking at the same time.

Hissing and sizzling: look for water

A hiss usually means water is going somewhere it should not. On a storage heater the pressure relief (safety) valve opens to let water out if pressure in the tank gets too high; a valve that hisses or drips constantly is either doing its job because pressure is too high, or is worn. Suruhanjaya Tenaga's wiring guideline, as quoted in our storage heater parts guide, says the valve must never be blocked or locked shut. Sizzling can also be water dripping from a leaking fitting onto a hot element or casing.

If water is coming from inside the casing, switch the heater off at its isolator before anything else; the element and electronics are in there. Our water heater leaking guide explains how to tell which part is leaking.

Humming and buzzing: pumps, elements and relays

A pump model hums whenever the pump runs, and inverter (DC pump) models are generally quieter than basic AC pump models. If the pump hums without pushing water, cycles on and off or rattles, our instant heater with pump guide lists air in the pump, a blockage or a worn pump as the usual causes; switch it off at the isolator and do not open the casing yourself. A heat pump water heater has a fan like an aircon outdoor unit, so a steady fan noise is normal there; the heat pump water heater guide covers placement.

A loud buzz or crackle from the control or wiring area is different: it can mean a loose connection or a failing relay, and it is an electrical fault rather than a plumbing one.

Clicking and ticking

A single click as the water starts or stops is the thermostat or flow switch, and it is normal. Rapid, repeated clicking, with the water going hot and cold, suggests the heater is struggling with low flow or pressure, or a sensor is failing. Ticking and creaking after a shower usually comes from the hot-water pipes themselves: they grow slightly longer as they heat and rub against clips, walls or ceiling boards. Our water hammer and noisy pipes guide covers that, and the banging sound when a tap is shut quickly.

Which noises are dangerous

• The RCD trips when the heater switches on. A cracked element can leak current to earth, and the RCD is doing its job. Do not keep resetting it.
• A tingle or shock from the tap or shower. Stop using the heater and switch it off at the isolator; our electric shock guide explains what to do next.
• A burning or hot-plastic smell, scorch marks or a switch that runs hot. Switch off and have the wiring checked.
• Water inside the casing, or the relief valve hissing constantly. Switch off and have it checked.
• Very loud banging or rumbling from a storage tank with very hot water. The thermostat or cut-out may have failed; switch it off.

Suruhanjaya Tenaga's guideline, quoted in our instant heater with pump guide, says a water heater must be permanently connected to its own breaker with an RCD of not more than 10 mA. A heater plugged into an ordinary socket, or sharing a circuit, needs an electrician's attention whatever the noise.

Repair or replace?

What it costs

These are ClickBina's published figures (indicative 2026, Klang Valley). Part repairs are priced after the unit is inspected, so the replacement figures are the yardstick.

When you send the job details, say what kind of heater it is, when the noise happens (heating, running, after use) and whether the RCD has tripped. That is enough to tell a scale problem from an electrical one.

How ClickBina can help

ClickBina is an experienced KL & Selangor contractor for whole-house refurbishment and trade coordination. WhatsApp us your job details for a quote: your area, the heater type, what the noise sounds like and when it happens. We reply within the hour, and the price we agree is a flat price with no hidden charges.

Sources & methodology

• ClickBina storage water heater parts guide — element, thermostat, anode and relief valve; scale on the element; Suruhanjaya Tenaga rule on the relief valve.
• ClickBina instant water heater with pump guide — pump noise causes; Suruhanjaya Tenaga RCD rule.
• ClickBina water heater leaking guide — replacement and circuit prices.
• ClickBina water hammer guide — pipe ticking and banging; call-out price.

How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above; they are indicative Klang Valley ranges for 2026. This page gives no brand-specific advice; follow the manual for your model.