Quick Answer: Elastane degrades from chlorine and sunscreen residue that stays in the fibers, so the deciding factor is a proper final wash — not how you fold it. Wash in cool water with a gentle detergent, dry completely flat and away from direct sun, then store flat or loosely rolled in a breathable container. Never store damp, never on a hanger, and never in a sealed plastic bag.

You had a great summer, the swimsuits are in a heap in a beach bag somewhere, and next June you will pull them out and discover that one has gone weirdly crunchy and another has lost all its snap.

That damage happens in storage, not in the water. The second section is the fifteen minutes that prevent it.

What actually destroys swimwear during storage?

Four things, and three of them are avoidable entirely.

Chlorine residue keeps working. Chlorine attacks elastane by breaking down the polymer chains that give it stretch. If chlorine is still in the fibers when you put a suit away, it continues degrading them for months in the dark. This is the main cause of a suit that felt fine in September and is baggy and rough by June.

Sunscreen and oils oxidize. Sunscreen ingredients, body oils, and self-tanner left in fabric oxidize over time, producing yellowing and stiffness. Certain sunscreen ingredients also react with chlorine to produce staining that becomes permanent once it has months to set.

Salt crystallizes. Dried salt is abrasive at the fiber level. Left in a folded suit, the crystals sit in the crease and work on the fabric every time it is moved.

Moisture grows things. A suit stored even slightly damp in a sealed container develops mildew, which produces odor that is often permanent in synthetic fabric and can cause spotting.

And one that surprises people: elastic degrades under sustained tension. A suit stored stretched — on a hanger by thin straps, or crammed tight into a full drawer — has its elastane held under load for months. Elastane recovers from repeated short stretches and does not recover well from months of constant ones.

What is the end-of-season wash routine?

Fifteen minutes total, and it does most of the work.

Step 1: Soak first, before washing. Cool water, 30 minutes, in a basin. This dissolves salt and loosens sunscreen residue before you introduce detergent. For chlorine-heavy suits, add a tablespoon of white vinegar to the soak — the acidity helps neutralize remaining chlorine.

Step 2: Hand wash in cool water with a gentle detergent. Cool, not warm. Heat is one of the fastest ways to damage elastane, and hot water sets sunscreen stains rather than removing them. Use a mild detergent or one formulated for delicates. Skip fabric softener entirely — it coats fibers and reduces the fabric’s recovery.

Step 3: Squeeze, do not wring. Wringing twists the elastane fibers against each other and permanently damages the stretch. Press the water out between your palms, then roll the suit in a towel and press.

Step 4: Dry completely flat, out of direct sun. Hanging a wet suit stretches it under the weight of the water. Direct sun degrades elastane and fades dye — the last thing a suit needs after a summer of it. Flat on a dry towel, turned once, until genuinely dry.

Step 5: Check dryness properly. Thick areas — padded cups, gathered panels, tie straps — hold moisture long after the flat sections feel dry. Give it another 12 hours after you think it is done. This is the single most common storage failure.

If a machine wash is unavoidable: cold, delicate cycle, mesh bag, no softener, and never a dryer.

How should you actually store them?

The principles are simple: flat, dry, breathing, and not under tension.

Store flat or loosely rolled. Flat is best. A loose roll is fine and saves space. What you are avoiding is sharp creases held for months, which weaken fibers along the fold line.

Never on a hanger. Thin straps holding the weight of a suit for nine months stretches them permanently. This is the most common cause of straps that no longer fit correctly next season.

Use a breathable container. A cotton bag, a pillowcase, or an open drawer. Sealed plastic bags and vacuum bags trap any residual moisture and give it nine months to become a problem. Vacuum bags also compress elastane under constant pressure, which is the exact condition it recovers from worst.

Separate light and dark. Dye transfer over months of contact is real, particularly with a bright suit against a white one.

Reshape padded cups before storing. Molded cups that are stored folded set in that shape. Store them nested and facing the same direction, like stacking bowls.

Cool, dark, dry location. An attic that hits 40 degrees in summer or a basement with humidity are both bad choices. A bedroom drawer is genuinely better than either.

Keep the mesh laundry bag with them so next season you already have it, and consider putting a note in the container listing anything that needs replacing — you will not remember in June.

5 Mistakes Everyone Makes Storing Swimwear

Mistake 1: Skipping the final wash because the suit was only in the ocean. Salt is abrasive and it is still there. A rinse at the beach shower is not a wash — it dilutes salt without removing sunscreen or oils.

Mistake 2: Storing it in the beach bag. The bag is damp, sandy, and probably has a wet towel in it. This is how a suit goes into storage with mildew already forming. Everything comes out of the bag at the end of the season.

Mistake 3: Waiting for a suit to dry in a bathroom. Bathrooms are the most humid room in the house. A suit that has hung in a bathroom for two days can still be holding moisture, particularly in seams and padding. Dry it flat somewhere with airflow.

Mistake 4: Using stain remover or bleach on sunscreen marks. Chlorine bleach destroys elastane outright, and many general stain removers are too aggressive for swimwear. For sunscreen yellowing, a long soak in cool water with a gentle detergent, repeated, is more effective and far safer than one aggressive treatment.

Mistake 5: Storing the one you should have thrown away. A suit that has lost its recovery — the fabric stays stretched when you pull and release it — will not come back over the winter. Check each suit’s snap before you store it, and keep the drawer for the ones that still have life. Storing a dead suit does not resurrect it; it just means you discover the problem on the first hot day next year.

FAQ: Swimwear Storage Questions, Answered

Does vinegar in the soak really help with chlorine?

It helps, modestly. A dilute vinegar soak can help neutralize residual chlorine and reduce odor, and it is gentle enough to be safe for elastane. It is not a substitute for a proper wash — do the vinegar soak first, then wash with detergent. Rinse thoroughly either way.

How long should a swimsuit actually last?

With regular pool use, a season or two is normal for a suit worn several times a week in chlorinated water, and considerably longer for one worn occasionally in the ocean. Chlorine-resistant fabrics — often polyester or PBT blends rather than nylon and elastane — last substantially longer if you swim laps regularly. If you are replacing suits every year, the fabric type may be the thing to change.

Should I store swimwear differently in a humid climate?

Yes, take the drying step even more seriously and choose breathable storage in the driest room you have. Avoid basements and unventilated closets. Some people add a moisture absorber to the storage container, which is fine as long as it is not in direct contact with the fabric.

TL;DR:

• Chlorine and sunscreen residue keep degrading elastane in the drawer — the final wash is what saves the suit.
• Soak in cool water first, hand wash cool with a gentle detergent, no softener, squeeze rather than wring.
• Dry completely flat and out of sun, then give it another 12 hours before you believe it.
• Store flat or loosely rolled in something breathable — never a hanger, never a sealed plastic or vacuum bag.
• Check recovery before storing; a suit that no longer snaps back will not improve over winter.

None of this is difficult, which is precisely why it does not happen — the end of summer is the least motivating time to do laundry with intent. But fifteen minutes now is the difference between opening a drawer next June and finding swimwear, or finding a small pile of expensive fabric that has quietly given up.