Uh oh. The time is drawing nigh when I have to buy a new dishwasher. We’ve had ours for around eight years, and while it’s still working well, there’s a good reason to start over by replacing it.

The reason is simple: water and energy. On average, according to the Energy Saving Trust (www.est.org.uk), new energy-efficient dishwashers use around 40 per cent less energy than those made in the technological Dark Ages known as the late 20th century. And according to Waterwise (www.waterwise.org.uk), while pre-2000 machines use an average of 25 litres of water per load, newer machines use just under 15 litres. Calculating on these figures, running an old machine twice a week would use around 1,000 litres more per annum.

Deciding to upgrade is easy. The hard part is choosing a new machine. But it’s made a little easier by Waterwise’s online league-table, which ranks machines according to energy efficiency, water use and water efficiency. An updated list will be going online in late August, so you might want to wait for the newer figures.

I’m still undecided on my choice, but I know that everyone has to consider some basic principles of Green Kitchen dishwasher use. One is that dishwashers must not be run until they’re full. If you have a full-size dishwasher, you need sufficient plates and cutlery to use while you’re waiting to fill it. If you don’t, you’ll be raiding the dishwasher to find the dishes you need – then washing them by hand.

Principle number two: don’t fill the machine inefficiently. If you have a full-size model, you may be tempted to pack it with saucepans and casseroles, just so you can run it at a reasonable interval to get plates and spoons clean. A saucepan can occupy the space used by six plates. Washing those big things in the dishwasher is a major waste of water and energy. Green Kitchenistas don’t do it, and I hope you won’t, either.

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