Sunscreen resistance claims don’t hold water

The protection offered by popular water resistant sunscreens plummets in conditions replicating swimming pools, the sea and fast-moving water, Which? has found.

The consumer champion tested water resistance claims made by two popular sunscreens – one own-brand and one well-known international product – and found the sun protection factor (SPF) dropped by up to 59% after forty minutes in salt water.

Water resistance claims are made on the majority of sun protection products, yet Which?’s findings expose serious flaws in the current testing regime – which only requires a volunteer to be immersed in a bath of tap water that circulates to simulate “moderate activity”.

The current tests also allow manufacturers to claim a product is water resistant if the SPF drops by up to 50% after two twenty minute periods of immersion.

Which? carried out more rigorous tests in salt water, chlorinated water and fast-moving water – conditions that more closely resemble those encountered on holiday.

Which? found that the well-known international product’s SPF dropped by 59% after 40 minutes of immersion in salt water and in moving water.

The popular own-branded product’s SPF dropped by 34% in both salt water and chlorinated water. But in reality, sun protection is likely to drop even further – factors such as reflection (from water), heat, light, sweat, towelling and rubbing all reduce the protection of sunscreens.

Which? believes the current requirements around the water-resistance claim are unrealistic to the point of being meaningless. Consumers could rely on a product to provide a level of protection that it is incapable of delivering, putting them at risk in the sun. There’s no way for consumers to know what SPF they’ll end up with after going into the sea or pool when they make a purchase.

Other countries – including Australia and the United States, have stricter requirements where the SPF on the label must be the SPF it provides after immersion in tap water.

In separate tests, Which? looked to see whether 15 widely available sunscreens meet their SPF claims, and all passed.

In 2017, Which? labelled Avon’s Sun+ Multi Protection Moisturising Sun Lotion SPF30 (150ml) a ‘Don’t Buy’ as the product failed the SPF tests. The sunscreen continues to be a ‘Don’t Buy’ this year as it has not been reformulated and is still available to buy.

Nikki Stopford, Which Director of Research and Publishing, said:

“Our research shows water resistant sunscreens don’t live up to their claims when subjected to rigorous tests – raising serious questions about the current guidelines.

“With 15,400 new cases of melanoma each year, manufacturers should be required to robustly test their products and make only claims that can be relied on, ensuring holidaymakers know they can trust their sunscreen to protect them.”



Notes to editors:


  • For more information on buying and using sunscreens and recommended Best Buys, head to
  • Water resistance for sunscreens is tested by:
    • Two sunscreens with water resistant claims were tested – a popular own-brand product and a well-known international product. Each product was tested in four different conditions.  
    • The test used an industry guideline that involves human volunteers being immersed in a bath of water. Volunteers do two stints of 20 minutes in the bath, broken up by 15 minutes during which they air-dry. The sunscreen’s SPF is compared before and after the two stints.
    • The guideline requires the use of tap water in a bath. Water continuously circulates so as to simulate ‘moderate activity’.
    • The guideline also allows for the SPF of the product to drop by up to 50% after immersion.
  • SPF was tested using the British Standard. The SPF testing involves:
    • Applying a set amount of sunscreen to an area on a volunteer’s back. A UV lamp, that simulates the rays of the sun, is then directed onto the area.
    • Recordings are taken when the skin turns red, comparing the smallest dose of UV light required to turn skin red, both with and without sunscreen. Each product is tested on ten volunteers.
    • UVA is tested using a British Standard. Unlike SPF testing, the Standard doesn’t require UVA to be tested on human volunteers. Instead, we use a spectrophotometer (a machine that measures light) to measure the amount of UVA radiation absorbed by the sunscreen.
  • Which? also has each product tested by a panel of volunteers to check whether it makes skin greasy or sticky. Consumers have told us they dislike using sunscreens that feel unpleasant.
  • According to Cancer Research UK, melanoma – the deadliest form of skin cancer – is the fifth most common cancer in the UK, with 15,400 new cases every year.
  • In 2017, Which? assessed a total of 14 sunscreen products from high-street brands and found that one sunscreen did not offer the protection it claimed in its tests:
    • It also looked at SPF claims used on make-up: For any product to offer the SPF it claims, you need to apply 2mg per cm2 –around a teaspoon of product would need to be applied to your face. And it needs to be regularly reapplied. In reality people are unlikely to apply the amount of make-up required – in the case of foundation, that would mean a 30ml bottle would only last six applications.
  • In 2016, Which? tested the claims of four ‘once-a-day’ sunscreens and found that they might not provide the cover they claim:
  • Full list of SPF30 tests:

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