What Is Limescale and Why Does It Form?
Limescale is a hard, chalky deposit composed primarily of calcium carbonate. It forms when hard water — water with a high mineral content — is heated. As the water evaporates or cools, the dissolved minerals are left behind as a solid deposit. The UK has extensive hard water areas: virtually all of London, the South East, Midlands, East Anglia, and parts of the North West have hard to very hard water.
Where Does Limescale Form in a Washing Machine?
The heating element is the most affected component — limescale deposits coat it and act as an insulator, causing it to overheat and burn out prematurely. In very hard water areas, elements in poorly maintained machines can fail within 3–4 years rather than the typical 7–10 years. Limescale also builds up on the drum interior, in pipes and hoses (reducing water flow), on the drum seal, and inside the pump and inlet valve.
How to Check Your Water Hardness
The water hardness in your area is measured in mg/l (or °dH, degrees of German hardness). You can find your local water hardness on your water company's website, or buy a simple test kit. As a rough guide: London water averages around 300 mg/l (very hard); Manchester averages around 60 mg/l (soft); much of the North West, Scotland, and Wales has soft to medium water.
Prevention: The Monthly Maintenance Wash
Run a monthly maintenance wash: empty drum, 90°C programme, with either a proprietary descaling/washing machine cleaner tablet (such as Dr. Beckmann Service-It or Calgon) or a cup of white vinegar in the drum. The hot wash dissolves existing limescale deposits and the descaling agent prevents new formation. This single habit can dramatically extend element life in hard water areas.
Descaling Agents: Tablets vs Powders vs Liquids
Dedicated washing machine descalers work better than general household descalers (like kettle descaler) — the formulations are designed for the temperatures and materials in washing machines. Citric acid-based products are effective and less chemically aggressive than hydrochloric acid-based alternatives. Run the descaler monthly in hard water areas; every 2–3 months in medium water areas; quarterly in soft water areas.
When Limescale Has Already Caused Damage
If your machine is taking longer to heat up, not reaching temperature, or has failed its heating element, limescale is likely involved. Get a diagnosis and quote for element replacement, and commit to a monthly maintenance wash afterwards to prevent recurrence. A new element in a machine that is not descaled regularly will fail again within a few years.