Boil only the water you need, with a lid on the pot
Over-filling the kettle and boiling pasta in an open pan quietly waste energy you're paying for. Two no-cost habits — measure your water and keep a lid on — shrink your daily kitchen power use.
The kettle is one of the most-used appliances in any European kitchen, and almost everyone over-fills it. We pour in enough for a pot of tea, make one mug, and tip the rest away — having paid to heat water that goes straight down the sink. Because each boil is cheap, it feels trivial. But you do it several times a day, every day, and at that frequency the small waste turns into a steady leak on the bill.
The physics is simple and forgiving: heating water takes energy in direct proportion to how much water there is and how far you raise its temperature. Boil a cup instead of a litre and you’ve cut the energy for that brew dramatically. Keep a lid on a pan and the steam — which is where the heat escapes — stays in, so the water boils sooner and you can ease off the dial.
The honest caveat is that no single boil saves you much; this is a habit that pays through repetition, not in one dramatic hit. There’s nothing to buy and nothing to remember beyond filling to the mug you’ll drink from and reaching for the lid. Progress, not perfection — and your tea arrives a little faster, too.
How to do it
- Before you flick the kettle on, pour cold water into the mug or jug you're actually using, then tip that into the kettle — so you heat one cup, not a full litre, for one cup of tea.
- Check your kettle's minimum line and don't go below it; most need the element just covered to switch on safely.
- When boiling on the hob, put a lid on the pan. Trapped steam means the water reaches the boil far faster and you can drop the heat to barely a simmer once it's there.
- Match the pan to the ring — a small pot on a big burner throws most of the heat up the sides and into the room, not into the food.
- Use just enough water to cover pasta, eggs or veg rather than drowning them; less water means less to heat and a quicker boil.
- Once it's boiling, turn the dial right down. A rolling, splashing boil isn't cooking any faster than a gentle one — it's just evaporating water and energy.
Pro tips & pitfalls
- If your kettle has a window or markings, learn where the one-mug and two-mug levels sit so you can fill by eye without measuring every time.
- Boiling water for pasta or veg? The kettle is usually more efficient than the hob, so boil it there first, then tip it into the pan.
What it's good for
Good for the planet
- Saves energy Boiling a single mug instead of a full kettle uses a fraction of the electricity, and a lidded pot reaches the boil with markedly less energy — both, several times a day, add up.
- Cuts CO₂ Less electricity drawn means fewer emissions from the grid behind it — small per brew, but you're doing it thousands of times a year.
Good for you
- Saves money Households often over-fill the kettle for every brew; measuring and lidding can quietly save around €10–25 a year off the energy bill, for no effort.
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