London has hard water — here's what that changes when you clean

Where your water comes from

Most of London — North London included — is supplied with hard water. It's drawn from the River Lee and the Thames and from chalk boreholes under the Lee Valley, and on the way it dissolves a lot of calcium and magnesium out of the chalk. That's what "hard" means: dissolved minerals that come back out of the water and set as scale wherever the water sits, dries or is heated.

It's the opposite of soft-water regions like much of Wales and the North West. Here, limescale isn't an occasional nuisance — it's the single most common cleaning problem in the borough, and it changes how you should clean.

What hard water changes

• Limescale builds everywhere the water sits. Kettle elements, showerheads, taps, the base of mixer spouts, toilet water lines, the bottom of glasses in the dishwasher. It looks like a chalky white or grey crust and it comes back — because the water keeps depositing more.
• You need an acid, not more scrubbing. Scale is a mineral, so it dissolves with a mild acid — a proper limescale remover, or white vinegar / citric acid on gentler jobs — not with more elbow grease. Scrubbing a scaled tap polishes it; it doesn't remove the scale underneath.
• Soap does less, so people use more. Hard water kills lather, so it's tempting to add more product. That leaves a sticky soap-and-mineral film — the "soap scum" on shower screens and tiles — which attracts more dirt. Use a normal dose and rinse well instead.
• Appliances scale up. Kettles, washing machines, dishwashers and boilers all fur up here. Descaling the kettle monthly and running a machine descaler now and then genuinely extends their life in London — that's not upselling, it's the water.

The mistake that wrecks shower glass

The big one: letting scale sit on the shower screen. In a hard-water area, every shower leaves a fine mineral mist on the glass. Wiped or squeegeed off while wet, it's nothing. Left to dry, day after day, it slowly etches into the surface of the glass — and once it's etched, no cleaner brings it back, because you're now looking at damage, not dirt. Keep a squeegee in the shower, and the screen stays clear for years.

What hard water doesn't change

Everything that isn't scale is exactly the same job as anywhere: grease in the kitchen, dust on skirtings and door tops, mould in the grout and around window seals, traffic marks on floors. Hard water just adds the limescale layer on top — which is why a proper deep clean here spends real time descaling taps, screens and tiles that a soft-water clean would skip entirely.