Waterblock Independent Testing: The Science Behind 8-Hour Water Resistance

If you have ever picked up a SolRX Waterblock lotion and noticed it says "Water Resistant (80 minutes)" on the Drug Facts panel, you might have wondered whether something changed. Nothing changed. That number is an FDA-mandated label requirement that applies to every sunscreen sold in the United States. It does not reflect the ceiling of Waterblock's performance. It reflects the ceiling of what the law allows brands to print on a bottle. This page tells the full story.

What Is the FDA Water Resistance Standard?

In 2011, the U.S. Food and Drug Administration issued its Final Rule for over-the-counter sunscreen labeling, which took effect in 2012. The rule standardized how brands could describe water resistance and removed absolute claims like "waterproof" and "sweatproof" across the entire industry. Under the new standard, a sunscreen can claim water resistance for either 40 minutes or 80 minutes, based on testing that shows the product maintains its rated SPF after repeated water immersion cycles. No sunscreen sold in the United States is permitted to claim more than 80 minutes on its label, regardless of how the formula actually performs. That industry-wide cap is what created the gap this page exists to close.

Why SolRX Needed a Different Test

SolRX was built for people who spend entire days in the water. Surfers. Triathletes. Open water swimmers. Lifeguards. Divers. For that audience, 80 minutes of water resistance is not a finish line. It is the first hour of the day. When SolRX developed the Waterblock system in the early years of the brand, the goal was not to meet a government standard. It was to find out how far beyond that standard the formula could actually go. SolRX commissioned an independent laboratory to design a performance test that was, by specification, tougher than any FDA or international government standard. The test was built from scratch, with a target of 8 full hours of water exposure, measuring SPF performance continuously throughout and again after the full 8 hours were complete.

The 8-Hour Immersion Test: What It Measured and What It Found

The protocol called for the SolRX SPF 30 Waterblock formula to be applied, then immersed in water for 8 consecutive hours with SPF monitoring throughout, followed by a full SPF measurement after the 8-hour period to assess residual protection. After 8 hours in the water, the SPF 30 formula measured SPF 35.83, holding its full rating across the entire immersion window. That result is the basis for the Waterblock name and the standard the brand builds every Waterblock lotion to.

What the FDA Labeling Change Actually Means

When the FDA's 2012 Final Rule took effect, SolRX updated its packaging language to comply. This is the part that has confused customers ever since, and it deserves a direct answer. The ruling was a labeling requirement. It applied to every sunscreen brand in the country. It did not require any brand to change its formula, and it did not invalidate any prior test results. It simply capped the water resistance time a product can state on its label at 80 minutes. SolRX complied with the law, updated the packaging language, and kept the formula exactly as it was. The Waterblock system has not been reformulated. The independent 8-hour immersion result stands. The Drug Facts panel reads "Water Resistant (80 minutes)" because federal law requires it, not because that is the limit of what Waterblock can do. For a deeper look at how Waterblock bonds to skin under prolonged water exposure, read The Science Behind SolRX Waterblock Technology.

Why SolRX Documents Its Testing

Publishing performance data is not required by law. SolRX does it because the data supports the product. The brand set out to build a test tougher than the federal standard, ran it to a full 8 hours, and keeps the result on record. That is the standard SolRX was built on: protection you can verify, not just a number printed on a label. When you reach for a Waterblock lotion, you are reaching for a formula measured against a deliberately harder benchmark than the law requires.

Which SolRX Products Carry Waterblock Technology

Waterblock technology applies exclusively to SolRX Sport Waterblock lotions. These are the formulas built around the bonding system tested in the 8-hour immersion protocol. SolRX sprays carry 80-minute water resistance and are excellent for active use, but they are not part of the Waterblock lotion system and do not carry the Waterblock designation. If 8-hour water resistance is what you need, the Water Resistant collection is where to start. For surfers, triathletes, and anyone spending a full day in the water, Waterblock lotions are the formula built for that reality. If you are shopping for a team, a crew, or a full season of training, the Bundles collection offers multi-pack options designed for high-volume use.

How Waterblock Fits Into a Complete Sun Protection Routine

8-hour water resistance is a significant performance advantage, but it does not replace a complete sun protection routine. The FDA recommends reapplying any sunscreen at least every two hours during outdoor activity, and immediately after towel drying, regardless of the water resistance rating. Waterblock gives you a longer window of reliable protection in the water. It does not eliminate the need to reapply when you come out, especially after rubbing down with a towel. Apply generously before sun exposure, allow 15 minutes before entering the water, and reapply when you are out and dry. For athletes managing long competition days or full training sessions, Waterblock removes the anxiety of watching the clock every 80 minutes while you are in the water. That peace of mind is what the formula was designed to deliver. For more on selecting the right sport sunscreen for your specific activity, read Best Sunscreens for Athletes.