Eco wash takes longer than a normal cycle, but here’s why that's a good thing.

You put a load of washing in the machine, select the eco programme and see the timer jump to 3 hours and 29 minutes. Meanwhile, the quick wash promises to finish in half an hour. Surely the shorter programme uses less electricity?

It sounds logical, but the opposite can be true. The eco programme is designed to save energy by changing how the wash works, rather than simply getting it over with quickly. And if you've been avoiding that button because of the long countdown, you might be missing an opportunity to reduce your laundry costs.

Why a longer wash can use less electricity

The biggest reason comes down to one thing: heating water.

A washing machine uses electricity to heat water, power the motor and run its other components. Heating water accounts for a substantial share of the energy used during a wash, so lowering the temperature can make a meaningful difference.

The eco programme takes advantage of this. Instead of relying on hotter water to get the job done quickly, it gives the detergent and washing action more time to work. The longer cycle allows the machine to clean clothes while limiting the energy used for heating.

This principle is supported by the US government's ENERGY STAR programme, which explains that water heating accounts for about 90% of the energy used to operate a clothes washer. Its advice is to wash in cold water when appropriate and run full loads to reduce energy consumption. The exact savings from an eco programme will depend on the machine and the cycle you're comparing.

According to Dutch environmental advice centre Milieu Centraal, the eco programme is the best choice for normally soiled laundry. It can also use less water than other programmes.

What does 'eco 40–60' actually mean?

If your washing machine was sold in the EU in recent years, you may have noticed a setting called eco 40–60. The name can be confusing: it doesn't mean the programme necessarily washes at 40°C or 60°C.

Since 1 March 2021, EU rules have required household washing machines covered by the regulation to offer this programme. It's designed to wash normally soiled cotton items labelled as suitable for 40°C or 60°C together in one load. The programme is also used to assess energy efficiency for EU ecodesign requirements and energy labelling. The EU regulation explains how it works.

The actual temperature depends on the machine and how the programme operates. It doesn't have to heat the water to 60°C simply because that number appears on the display. The point is to clean the laundry efficiently while keeping energy and water consumption down.

The rules also place limits on programme duration, with the permitted maximum depending on the machine's rated capacity and the size of the load. So a long cycle isn't necessarily a sign that your machine is malfunctioning.

Does the eco programme clean as well?

There can be trade-offs. In tests reported by Dutch consumer programme Kassa, the eco 40–60 cycle took around 200 minutes on average across the machines tested. The eco wash also cleaned slightly less effectively than the standard 40°C cotton programme in most of those machines.

That doesn't mean eco is a poor choice for everyday laundry. It is intended for normally soiled clothes, not necessarily for every stubborn stain or heavily soiled item. Results can also vary between machines.

For dishwashers, Milieu Centraal reports that the eco programme can use more than 25% less electricity and more than 20% less water than the standard programme. The exact savings depend on the appliance and the programmes being compared.

When should you use a different programme?

For everyday laundry, a full drum and the eco setting are usually a sensible combination, provided you don't overload the machine. Running it overnight or before leaving for work can make the longer cycle easier to fit into your routine.

There are times when another programme makes more sense. Clothes with stubborn stains or heavily soiled items may need a different wash, while bedding and other items that require a specific hygiene treatment should be washed according to their care labels and the machine's instructions.

A quick wash is useful when you're short on time, especially for a small load of lightly soiled clothes. Just don't assume that a shorter cycle automatically means a lower electricity bill.

The next time your washing machine displays a three-hour countdown, resist the urge to switch straight to the quick wash. For a normal load, giving the eco programme more time could be one of the simplest ways to reduce the energy your laundry uses.