Rinse it immediately, even if it's 'chlorine resistant

Rinse it in cold water as soon as you get out of the pool.

That’s it. That’s the most important thing. “Chlorine resistant” fabrics (usually polyester or PBT) last longer than cotton blends or plain spandex, but they’re not magic. Chlorine still attacks the elastic and the fibers over time. Rinsing flushes out the bulk of the chemical damage before it sets.

Don’t wring it out. Don’t toss it in the washing machine on hot unless the tag explicitly says you can. Don’t leave it balled up in a wet towel or a plastic bag for hours. Lay it flat to dry away from direct sun. Heat and UV are the other enemies.

The “resistant” label mostly means the fabric won’t fade or disintegrate as fast as cheap swimwear. It doesn’t mean you can ignore basic care. Treat it like a good pair of workout leggings: rinse, gentle dry, repeat.

Your swimsuit will last years instead of months