Water Resistance

What Is Water Resistance?

The water resistance study examines to what extent a sunscreen retains its protection level after being in water. The method relies on comparing protection values measured before entering water and after a defined water-immersion programme.

Purpose of Water Resistance

The purpose is to generate the technical basis for the 'water-resistant' or 'very water-resistant' claim on the label. These claims must be verifiable in the EU; an unsubstantiated claim is against the regulation.

Which Products Is Water Resistance Applied To?

Sunscreen creams and lotions
Sunscreen products in spray and stick form
Children's sunscreen products
Sports and beach products
Makeup products claiming water resistance

In Which Sectors Is Water Resistance Used?

CosmeticsPersonal CareRetailChemistry

Standards Related to Water Resistance

ISO 18861 (water resistance of sunscreen products — protection retention)
ISO 24444 (in vivo determination of SPF)
ISO 24443 (in vitro determination of UVA protection)
EU 655/2013 (common criteria for cosmetic claims)

Water Resistance Conditions

aquatic program: Immersion and rest cycles defined in the standard
water conditions: Temperature and movement conditions are defined in the standard
Comparison: Protection values before and after entering the water
Application: The product is applied in the amount and method defined in the standard.

Equipment for Water Resistance

Temperature-controlled water tank and circulation setup
SPF measurement setup (in vivo or in vitro depending on method)
UV source and spectroradiometer
Application and weighing equipment

Sample Requirements for Water Resistance

The product must be sent in its original, unopened packaging.
Batch number, manufacturing and expiry dates must be stated.
The ingredients list (INCI) and formulation information, if any, must be shared.
The required quantity varies by number of analyses; confirmation must be obtained before shipment.
Light- and temperature-sensitive products must be transported under suitable conditions.

Duration of Water Resistance

The study takes a few days including the water-immersion programme and measurements; planning time is additionally added for in vivo methods requiring participants.

Water Resistance Procedure

1The resistance level the product will claim is determined.
2The protection value before water entry is measured.
3The product is applied at the amount specified in the standard and allowed to dry.
4Defined immersion and rest cycles are applied.
5The protection value after water immersion is measured.
6The retained protection ratio is calculated by comparing the two values.
7The level that can be claimed is determined.

Water Resistance Acceptance Criteria

The acceptance criterion for cosmetic products does not come from a single test but from the product's safety assessment report and the regulation. EU 1223/2009 and the Cosmetics Regulation define prohibited and restricted substances, microbiological expectations, and labelling requirements; this page therefore does not give a fixed limit.

Evaluation of Results

Assessment relies on the retained protection ratio after water immersion meeting the level the standard requires for the claim. The 'water-resistant' and 'very water-resistant' claims correspond to programmes of different duration; which can be declared is determined by the result.

Water Resistance Report

Product name, batch number, and packaging information
Sample receipt date and storage conditions
Method applied and reference standard
Test conditions and conditioning, if any
Measurement results and units
Measurement uncertainty (if requested)
A statement that the result applies only to the specimen submitted for testing

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

EU 1223/2009 Cosmetic Products Regulation
Cosmetics Regulation (Türkiye)
Cosmetic Product Safety Report (CPSR) requirements
ISO 22716 (good manufacturing practice in cosmetics)

Kozmetik Testleri — What Does This Testing Field Cover?

The section below describes the field that the Water Resistance test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Cosmetics testing shows that a product stays microbiologically safe throughout its use, delivers the performance it claims and contains no restricted substances. There is NO PRODUCT APPROVAL in this family: no authority approves a cosmetic product; responsibility rests entirely with the manufacturer and with the responsible person established in the EU.

This responsibility model shapes how the field works. Before the product is placed on the market a product information file (PIF) is prepared, a safety assessment (CPSR) is carried out and notification is completed. Inspection comes afterwards and asks for the file; if the file is incomplete the product is withdrawn from the market. Test reports form the evidence base of that file.

On the microbiological side there are two different questions and each is answered by a separate test. The CURRENT microbiological quality of the product is measured by enumeration and testing for specified microorganisms. The EFFECTIVENESS of the preservative system is examined by deliberately inoculating the product with microorganisms (challenge test): can the product resist repeated contamination throughout its use? A jar of cream is touched by a finger at every use; the preservative system must cope with that.

On the performance side, claim substantiation studies are carried out. For sunscreens, determination of SPF and UVA protection and measurement of water resistance are mandatory and are the basis of the value declared on the label. Evidence is also produced by in vivo or in vitro methods for claims such as moisturisation, appearance of wrinkles, hair care and colour retention.

On the chemical side, banned and restricted substances are screened: heavy metals, prohibited colorants, preservative concentrations, UV filter levels and contaminants such as nitrosamines. Products containing nanomaterials carry a separate notification obligation.

The BAN ON ANIMAL TESTING is the most defining constraint of the field. Animal testing cannot be carried out on finished products or ingredients, and a product tested on animals cannot be placed on the market. Alternative in vitro methods (reconstructed human skin models, cell culture based tests) are therefore at the centre of the field, and toxicological assessment rests largely on existing data, read-across approaches and in vitro results.

Stability and packaging compatibility studies determine shelf life and the period after opening (PAO). The interaction of the product with its packaging is also assessed: an active substance may migrate into the packaging, and substances that should not be present may pass from the packaging into the product.

On the process side, good manufacturing practice is demonstrated through ISO 22716; this is separate from product testing but a mandatory part of the file.

Method groups in this field

Microbiological quality
Enumeration of aerobic mesophilic bacteria, yeasts and moulds; testing for Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and E. coli.
Preservative efficacy
Resistance of the preservative system to repeated contamination by challenge test (ISO 11930).
Sun protection
In vivo SPF determination, in vitro UVA protection determination, water resistance and critical wavelength measurements.
Chemical analysis
Heavy metals, banned and restricted substances, quantification of preservatives and UV filters, contaminant screening.
Safety assessment
In vitro irritation and sensitisation methods, toxicological risk assessment, exposure calculations.
Stability and compatibility
Real-time and accelerated stability, packaging compatibility, PAO determination, sensory and physicochemical monitoring.

Commonly confused in this field

There is NO CE marking on cosmetics; conformity is demonstrated through the PIF, the safety assessment and notification.
The responsible person must be established in the EU; unless the exporter arranges this, the product cannot be placed on the market.
Microbiological quality and preservative efficacy are different tests; a product that comes out clean may still have a weak preservative system.
The animal testing ban covers ingredients too; animal test data generated for another market creates a problem of use.
An SPF claim must be supported by measurement; a formulation change requires a new measurement.
A change of packaging may require the stability and compatibility studies to be repeated.

Which decisions these results support

The product information file and the safety assessment
Verification of the preservative system design
Substantiation of SPF and efficacy claims
Determining shelf life and the period after opening
Compliance with destination market restrictions for export

Related Tests

Frequently Asked Questions About Water Resistance

Can 'waterproof' be claimed?

No. An absolute claim such as 'waterproof' is not accepted under EU practice; the product can only be declared 'water-resistant' at the verified level.

Does the SPF value drop after water immersion?

It generally drops somewhat. What matters is that the drop stays within the limit the standard allows; the SPF declared on the label is determined accordingly.