Water resistance is a testable sunscreen claim
International sunscreen-testing standards include procedures for assessing water resistance. ISO 16217:2020 specifies a water-immersion procedure for determining sunscreen water resistance, while ISO 18861:2020 describes comparing SPF before and after a fixed period of water immersion to calculate retained protection.
What the words do not mean
- They do not mean the product is waterproof.
- They do not mean the sunscreen cannot be removed by swimming, sweating or towel drying.
- They do not tell you the test duration unless the label or manufacturer provides that information.
Check the exact manufacturer wording
Brands may use wording such as “water resistant”, “sweat resistant” or both. Record the exact claim rather than converting several different phrases into one generic rating.
Example of a current brand claim
Minimalist currently describes its Light Fluid SPF 50 Sunscreen as water- and sweat-resistant. That statement is a manufacturer claim; the exact product page and current pack should be used when documenting the claim.
How to compare two sunscreen labels
- Record SPF and UVA/PA information separately.
- Record the exact water-resistance wording.
- Check whether the manufacturer identifies a test method or supporting data.
- Keep reapplication directions separate from the performance claim itself.
Related: What Does SPF 50 PA++++ Mean?
Sources
- ISO 16217:2020 — Water immersion procedure for determining water resistance
- ISO 18861:2020 — Percentage of water resistance
- Minimalist Light Fluid SPF 50 Sunscreen
Last checked: 26 September 2026. This page explains label terminology and does not provide personalised medical advice.