Water Resistance Testing Explained
Water resistance is an important consideration for sunscreens designed for swimming, sport or other activities where the product may be exposed to water or sweat.
In Australia, a sunscreen cannot simply be described as water resistant because the formula is designed to stay on the skin. The claim needs to be supported by appropriate testing and meet the requirements of the Australian/New Zealand Sunscreen Standard.
For brands developing sunscreen, understanding the intended water-resistance claim early helps the formulation and manufacturing teams plan the product and its testing pathway.
What Does Water Resistant Sunscreen Mean?
A water-resistant sunscreen has been tested to assess how its SPF performs after a defined period of water immersion.
It does not mean the product is waterproof or that it will provide the same level of protection indefinitely while swimming or exercising.
During testing, sunscreen is applied according to the relevant test method and exposed to controlled periods of water immersion. SPF is then assessed following that water exposure.
The results are used to determine whether the product can support the intended water-resistance claim.
For brands, the main thing to understand is that SPF and water resistance are related, but they are not the same claim.
A sunscreen can achieve a particular SPF without automatically being able to claim water resistance.
How Does Water Resistance Work in Australia?
Sunscreens supplied in Australia need to meet the applicable requirements of the Australian/New Zealand Sunscreen Standard, AS/NZS 2604:2021.
For new therapeutic sunscreens included in the Australian Register of Therapeutic Goods, or ARTG, from 1 July 2024, the 2021 standard applies.
Under the Australian standard, the maximum water-resistance claim is linked to the SPF demonstrated by the product.
For sunscreen products with:
- SPF 8 to less than SPF 15: a maximum water-resistance claim of 40 minutes
- SPF 15 to less than SPF 30: a maximum claim of 2 hours
- SPF 30 or above: a maximum claim of 4 hours
This means a brand developing an SPF 50+ sunscreen may aim for a water-resistance claim of up to four hours, but that claim still needs to be supported by the required testing.
The maximum claim is not automatically given to the product because of its SPF.
How Is Sunscreen Water Resistance Tested?
Water-resistance testing is carried out under controlled conditions using recognised test methods.
The exact procedure is managed by the specialist sunscreen testing facility, but for a brand the basic process is relatively simple to understand.
1. The Sunscreen Is Applied
A defined amount of sunscreen is applied to the test area according to the relevant method.
2. The Product Is Exposed to Water
The test subjects complete controlled periods of water immersion.
The total immersion time depends on the water-resistance claim being assessed.
3. SPF Is Assessed After Water Exposure
Following the required water immersion, SPF testing is carried out.
This assesses the sunscreen’s SPF after it has been exposed to the defined water conditions.
4. The Results Are Reviewed
The testing results are then assessed against the requirements of the Australian standard and the claim the brand intends to make.
For brands, the detailed testing procedure does not need to be understood in the same way a testing laboratory would understand it.
The important questions are what water-resistance claim the product is being developed for and what testing is required to support it.
What Role Do ISO Standards Play?
The Australian/New Zealand Sunscreen Standard incorporates internationally recognised ISO testing methods.
For water resistance, ISO 16217 sets out the water-immersion procedure used when assessing sunscreen water resistance.
ISO 18861 provides a method for evaluating the percentage of water resistance by comparing sunscreen performance before and after water immersion.
These standards provide the testing methods used within the wider Australian framework.
For a brand, it is useful to distinguish between the testing method and the claim that ultimately appears on the product.
The testing may use an ISO method, but the finished sunscreen still needs to meet the Australian requirements that apply to the intended claim.
Does SPF Determine Water Resistance?
SPF influences the maximum water-resistance duration that can be claimed in Australia, but a high SPF does not automatically mean a sunscreen is water resistant.
For example, an SPF 50+ product may be eligible for a water-resistance claim of up to four hours under the Australian standard.
It still needs appropriate testing to support the water-resistance claim being made.
This is why SPF testing and water-resistance testing should be treated as different parts of the sunscreen testing pathway.
Does Every Sunscreen Need to Be Water Resistant?
No.
Not every sunscreen needs a water-resistance claim.
A daily facial sunscreen designed primarily for everyday wear may have a different brief from an SPF developed for swimming, sport or extended outdoor activity.
Whether water resistance should form part of the product brief depends on how the brand wants the sunscreen to be used and positioned.
If water resistance is important to the product concept, it should be discussed early in development rather than added as a claim once the formulation is complete.
What About Secondary Sunscreens?
This is particularly important for brands developing products such as moisturisers that also contain SPF.
In Australia, some secondary sunscreens can be excluded from therapeutic goods legislation when they meet specific criteria.
For certain secondary sunscreen categories, including qualifying moisturising skincare and sunbathing skincare products, one of the requirements for exclusion is that the product is not presented as water resistant.
If the product does not meet the relevant exclusion criteria, it may instead fall within the therapeutic sunscreen pathway and need to be included in the ARTG.
This is why the intended SPF, claims and product positioning should be considered together when developing a sunscreen product.
Who Is Responsible for the Water-Resistance Claim?
For therapeutic sunscreens in Australia, the sponsor is responsible for holding appropriate evidence to support the claims made for the product.
This includes water-resistance claims where they are made.
The product also needs to meet the testing and labelling requirements that apply under the Australian sunscreen framework.
For a brand new to SPF manufacturing, this does not mean you need to organise or interpret the testing yourself.
Your formulation, manufacturing, regulatory and external testing partners can help establish what is required for the individual product.
When Should Water Resistance Be Considered?
Ideally, it should be part of the original SPF brief.
If the product is intended for swimming, sport, beach use or another situation where water resistance is important, tell the formulation team at the beginning of development.
Useful things to establish early include:
- Target SPF
- Intended water-resistance claim
- Intended product use
- Product format
- Desired texture and finish
- Australian regulatory pathway
This gives the formulation team a clearer understanding of what the finished sunscreen is intended to achieve.
It also allows the required external testing to be considered within the wider development timeline.
What Happens if the Intended Claim Is Not Supported?
Testing provides information about whether the product supports the intended water-resistance claim.
If the required result is not achieved, the product and testing pathway will need to be reviewed.
Depending on the circumstances, further formulation work or repeat testing may be required before the intended claim can be used.
This is one reason brands should avoid finalising claims and packaging too early in SPF development.
Water Resistance and SPF Development at Delta
Delta works with skincare and personal care brands across SPF formulation development and commercial sunscreen manufacturing in Australia.
If water resistance is part of the product brief, the intended claim can be considered during formulation development alongside the target SPF, product format and intended use.
Depending on the project, Delta can support:
- SPF formulation development and refinement
- Lab samples
- Stability testing
- Planning for required external SPF and water-resistance testing
- Manufacturing scale-up
- Commercial manufacturing
SPF and water-resistance testing that requires specialist external testing facilities is planned as part of the wider development pathway.
For brands, discussing the intended claim early gives everyone involved a clearer understanding of the product being developed before packaging and launch plans are finalised.
FAQ: Water Resistance Testing in Australia
What does water resistant sunscreen mean?
It means the sunscreen has been tested to assess its SPF after a defined period of water immersion and has met the requirements needed to support the water-resistance claim being made.
What is the maximum water-resistance claim in Australia?
The maximum depends on the product’s SPF. Under the Australian standard, SPF 30 and above can support a water-resistance claim of up to four hours where the required testing criteria are met.
Does SPF 50+ automatically mean four hours water resistant?
No. SPF 50+ allows for a maximum claim of up to four hours, but the product still needs appropriate testing to support the water-resistance claim.
Can an SPF 15 sunscreen be water resistant?
Yes, where the applicable testing requirements are met. Under the Australian standard, products with SPF 15 to less than SPF 30 can support a maximum water-resistance claim of two hours.
Is water-resistance testing the same as SPF testing?
No. SPF establishes the sun protection factor of the product. Water-resistance testing assesses SPF following defined periods of water exposure.
Does every sunscreen need water-resistance testing?
No. Water-resistance testing is relevant when a brand intends to make a water-resistance claim.
Can a secondary sunscreen claim water resistance?
It depends on the product and regulatory pathway. For some secondary sunscreen categories, being presented as water resistant means the product will not meet the criteria for exclusion from therapeutic goods legislation. The individual product should therefore be assessed before the claim is finalised.
Developing a Water-Resistant Sunscreen?
If water resistance is part of your SPF concept, it is worth discussing the intended claim while the product is still being developed.
Delta works with brands across SPF formulation development, scale-up and commercial manufacturing, with external testing requirements considered as part of the development pathway.
Speak to Delta
Talk to Delta about your SPF product, intended water-resistance claim and commercial manufacturing requirements.