Can you wash up in cold water? Washing-up myths bustedThe best washing-up liquid: Fairy, Persil and more

28 November 2015

Woman washing-up with child

Is Fairy the queen of washing-up liquids? Our tests reveal the best

Which? washing-up liquid tests reveal much more than just the Best Buy products and the ones to avoid. Here, our washing-up experts share what you need to know about washing up.

Over two-thirds of us (67%) wash up by hand on a regular basis and we all have our own preferences. Rubber gloves are worn by 26%, for example, and 59% rinse each item in clean water after washing*.

But opinions also differ on whether you can wash-up in cold water, if a bubblier washing-up liquid is always better, and how much washing-up liquid you really need for the dirtiest cookware. Read on for our expert tips.

We recently tested 15 washing-up liquids from brands including Fairy, Persil, Ecover and major supermarkets. Our tests revealed three Best Buys and two products which scored so poorly we labelled them Don’t Buys and recommend you avoid them. 

Want to know which washing-up liquids are best and worst? Check our full washing-up liquid test results.

Washing-up liquid and cold water

To do a good job of getting your dishes clean, hot water is best. Increased temperature improves the performance of detergents’ ingredients and helps melt fat on dishes. Four factors influence cleaning: water temperature, the chemistry of the washing-up liquid, your scrubbing action, and the time you spend washing-up. If you change one, another must also change to get the same result.

So don’t panic if cold water is your only option (your Christmas guests have emptied the hot water tank, for example). It’s possible to get your plates clean in colder water, but you’ll need to scrub for longer or with more effort to get your dishes as clean as usual.

We use warm water in our tests – like you would at home – to make sure that we find the best products for your washing-up. Skip straight to Best Buy washing-up liquids to see the star performers.

Bubbles aren’t always better

Foam is a useful indicator to change the water or add more washing-up liquid; that’s why we look at it in our tests. But our results show that there’s no direct link between longer-lasting bubbles and better fat-removing power.  

Some washing-up liquids produce bubbles as a by-product of cleaning, but others have added foaming agent so they’ll make lots of bubbles regardless of cleaning. That’s where our test results come in: they separate bubbles from cleaning power so you can find the product that’s best for you.

The limits of washing-up liquid cleaning power

When you’re scrubbing away at stubborn stuck-on food, it’s tempting to squirt in lots of extra washing-up liquid in an attempt to shift it. But covering the offending item with a generous amount of washing-up liquid will only make your task easier up to a point.

Some detergents’ performance ‘plateaus’ - so after you’ve added a certain amount of washing-up liquid to the water, it reaches its maximum performance. Whether you add another spoonful or bucketful, it won’t make your washing up any easier and excess detergent will just be washed away. The actual amount of washing-up liquid it takes to reach that plateau depends on the product you’re using.

*(Online survey of 895 Which? members who regularly wash up by hand, June 2015.)

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