Most swimmers only think about water getting into a wetsuit when it's already too late. Mid-race, first buoy, that cold rush down the spine. By then you've stopped to adjust something, lost ten seconds, and you're still guessing whether the problem is the suit, the size, or how you put it on that morning. There's a better way to find out, and it takes about ten minutes in a bathtub before you ever get near open water.
Water Getting In Isn't Automatically a Problem
A wetsuit isn't built to keep you dry. It's built to let a thin layer of water in, which your body then warms against your skin. That warmed layer is part of the insulation system, not a flaw in it. So a leak check isn't really about finding zero water entry. It's about spotting where water keeps flushing in and out, because that's what actually costs you warmth, and more often than not, it's a sign of a fit problem rather than anything wrong with the wetsuit itself.
Swimmers who complain about a "leaky" wetsuit usually don't have a defective product. They have a fit issue at the neck, wrists, ankles, or zipper that's letting water cycle through continuously instead of settling and doing its job.
The Test
Put the wetsuit on exactly how you would on race morning. Pull it up snugly into the crotch first, then seat the shoulders before you zip. Get into a bathtub, shallow pool, or shower with the suit fully closed. Stand still for about a minute. Then move: rotate your shoulders, swing your arms through a freestyle recovery, do a few bodyweight squats to mimic the hip drive of a stroke.
Here's what you're watching for: does the water rush in once and settle, or does it keep flushing every time you move?
- A wetsuit that fits well: brief coolness at the neck, wrists, ankles, and zipper, then it stabilizes.
- A wetsuit with a fit problem: the same spot floods with cold water every time you move, because a gap is opening and closing with your motion instead of sealing.
Three Places Fit Problems Show Up
The Neck
This is the most common source of ongoing flushing, and it's rarely about the suit being poorly made. Usually it's one of two things: the collar is too loose for your neck, or it sits too high and catches your chin when you turn to breathe or sight. Blue70's Femme Fit pattern uses a lower-sitting neckline for exactly this reason. A high collar doesn't work well with the neck extension many women's anatomy requires through a stroke cycle, and that mismatch opens a channel for water on every breath.
The Wrists and Ankles
These openings need to stay snug when your arm reaches full extension on the catch or your ankle flexes on a kick. Slide more than a finger under the cuff with your arm stretched out, and water will flush there on every stroke in open water, not just during a quiet test at home.
The Zipper
A back zipper backed by a functional garage flap should stay sealed against your body through shoulder rotation. Feel a cold line tracking right along the zipper track when you rotate? That's usually a torso fit issue, not a hardware issue. The suit is gapping slightly through the back with each stroke.
Why a Quiet Bathtub Test Isn't the Full Picture
Swimming isn't static. Race-effort stroke rate runs well above the slow arm circles most people do standing in a shower, and a faster stroke rate means the gaps at your neck, wrists, and zipper open and close more often per minute. More cycles means more water pumped through in less time. A suit can pass a lazy test in a shallow pool and still feel like it's taking on water once you're actually working hard.
The fix is simple. After your first minute of standing still, add thirty seconds of faster arm circles and shoulder rolls, quicker than feels natural at rest. That's a much closer approximation of race pace than slow movement.
What a Passing Result Looks Like
You're checking for four things:
- Brief, one-time water entry at the neck, wrists, and ankles when you first submerge
- No new cold rushes at those same points once you start moving
- No cold line forming along the zipper during shoulder rotation
- No pooling in the lower back or seat, which suggests the torso is loose enough to hold a reservoir of cold water
Get all four, and the suit fits. Any water still moving through it is doing exactly what neoprene is supposed to do: warming up against your skin instead of constantly getting replaced by cold water from outside.
Sizing Problem or Donning Problem?
These two failures look similar in a bathtub, but the fix for each is completely different.
If water is flushing broadly across the torso, not just at the extremities, the suit is probably too big through the body. Blue70's size charts map height and weight to a size range, and if you land right on the border between two sizes, the general rule for a swim-specific wetsuit is to size down rather than up. A suit that feels snug on dry land is supposed to feel more comfortable once you're in the water and the neoprene settles against your skin.
If the fit looks right on paper but you're still getting flushing at the neck or shoulders, check how you're putting the suit on before you assume you need a different size. Neoprene bunched up at the shoulders, or a collar pulled crooked while you fought your way into the suit, creates channels that a well-fitted wetsuit shouldn't have. Take an extra thirty seconds to smooth everything into place at the shoulders and neck before you zip. Small habit, real difference.
Build This Into Race Week
The best time to run this test isn't the day you buy a new wetsuit. It's the week before a target race, once you've logged some open water sessions in the suit and the neoprene has gone through a season of stretch and use. Fit shifts a little over time, especially around the neck and cuffs where the material flexes constantly. A five-minute retest before race day costs you nothing. It tells you whether you need to adjust your donning routine, use lubricant more deliberately at the collar and cuffs, or start thinking about whether the suit is nearing the end of its useful life.
Blue70 offers a Test Swim option because fit assessment in open water is different from fit assessment in a bathtub. A careful home leak check is a preview, not a substitute, for time in the water. But running this test before you ever reach a start line means you're troubleshooting in your bathroom on a Tuesday night, not at the first buoy on race morning.
Happy swimming.
