Water Heater Leaking
What to Do, Where It Leaks & Repair or Replace (2026)

What to do first

1. Switch the heater off at its double-pole switch or isolator, or at the distribution board if the switch is wet.
2. Close the cold-water valve feeding the heater, or the main valve if there is none.
3. Do not touch the heater, the switch or wet cables if water is running near them.
4. Catch the water and protect the floor or the ceiling below.
5. Note where the water appears and whether it is hot or cold. That tells you most of what you need.

If the breaker or RCCB has tripped, leave it off. It is telling you water has reached something live.

Where is it leaking from?

Instant water heaters

Most Malaysian bathrooms have an instant heater on the wall beside the shower. Leaks usually come from the inlet and outlet fittings underneath, from the shower hose, or from inside the unit when an internal pipe or seal fails. A leak at a fitting is a small job. Water coming from inside the casing is more serious because the heating element and electronics are in there; switch it off and have it checked before using it again. Our instant water heater with pump guide explains how pump models differ.

Storage water heaters

A storage heater keeps a tank of hot water and has more parts that can leak: the relief valve, the inlet and outlet fittings, the element seal and the tank itself. Inside most steel tanks is an anode rod that corrodes instead of the tank; once it has been eaten away, the tank starts to rust from the inside, and a rusted-through tank cannot be repaired. Rusty hot water while the cold is clear can be an early sign. Our storage heater parts guide explains each part.

A dripping pressure relief valve

Heating water makes it expand, and the relief valve lets a little water out to stop the pressure building to a dangerous level. As quoted on our storage heater parts guide, Suruhanjaya Tenaga's domestic wiring guideline says an electric storage heater must not be operated without a pressure relief valve and an isolation barrier, and that those devices must not be obstructed, locked or closed.

• An occasional drip while heating can be normal expansion.
• A constant drip suggests a worn valve, grit on the seat or high supply pressure. It needs checking, not plugging.
• A valve that has never released any water may be seized, which is the more dangerous failure.
• The drain line must run somewhere safe and visible, never capped or hidden in a closed ceiling.

Leaks you find in the ceiling

Storage heaters are often hidden above a bathroom ceiling, so the first sign of a leak is a stain on the ceiling below. It may be the heater, its relief-valve drain, a concealed hot-water pipe, or something else entirely, such as the unit above. Our aircon leak vs pipe leak guide explains how to tell water sources apart. If a concealed pipe is suspected, leak detection pinpoints it so only one opening is made; our concealed pipe leak detection guide explains how it works.

Repair or replace?

A part repair makes sense when the tank is sound: a fitting, a washer, a relief valve or a hose. Once the tank is leaking or rusting through, the only fix is a new heater. Age matters too: our storage heater parts guide notes that a heater near the end of its life with several failed parts is usually better replaced than repaired twice. For an instant heater, compare the cost of the repair with a new unit, which is often not much more.

Electrical safety when replacing

A water heater is wiring as well as plumbing. As quoted on our socket placement rules guide, Suruhanjaya Tenaga's guideline requires a water heater circuit to be permanently connected, with a residual current device of not more than 10 mA, and the heater needs a double-pole or isolating switch; a plug and socket must not be used to connect it. The electrical side must be done by a wireman registered with Suruhanjaya Tenaga.

Choosing a replacement

If the heater has to go, it is a chance to check you still have the right type: instant, instant with pump, storage or another system. Think about how many showers run at once, the water pressure, and the space. Our water heater types guide compares them, and the installation cost guide sets out unit and installation prices.

What it costs

These are indicative Klang Valley ranges for 2026 from the ClickBina guides named in the sources section. Part repairs are quoted after the heater has been looked at.

How ClickBina can help

ClickBina is an experienced KL & Selangor contractor handling whole-house refurbishment and trade coordination, so a heater replacement, any ceiling repair and the bathroom finishes can be planned together. WhatsApp us your job details for a quote: the type and brand of heater, where the water is coming from and whether the ceiling is stained. We reply within the hour, the price we agree is a flat price with no hidden charges, and a site visit is RM150, waived if you go ahead. Leak detection is RM300–RM800 and is charged separately.

Sources & methodology

• ClickBina storage heater parts guide — relief valve and anode facts, the Suruhanjaya Tenaga relief-valve rule, storage heater and circuit prices.
• ClickBina water heater installation cost guide — instant heater prices.
• ClickBina socket placement rules guide — the water heater circuit rule quoted above.
• ClickBina concealed pipe leak detection guide — leak detection price.
• ClickBina toilet bowl types guide — site visit wording.

How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above. They are indicative Klang Valley market ranges for 2026, not fixed rates.