Rinse your swim trunks in fresh water after every swim, wash them gently with cold water and mild detergent when needed, skip bleach and fabric softener, and always air dry instead of using a dryer. Those few habits do more for the life of a pair of swim trunks than anything else.
Why Swimwear Care Matters
A regular pair of shorts deals with sweat and daily wear. Swim trunks deal with salt, chlorine, UV exposure, sand, sunscreen, body oils, heat, and repeated drying, often all in the same afternoon. Over time, those elements can weaken fabric, fade color, affect stretch, and make a liner feel less comfortable than it did on day one.
None of that means swim trunks are fragile. It means they respond well to a little basic care. The way you rinse, wash, dry, and store them has a direct effect on how long they keep their shape, softness, and quick-dry performance.
1. Rinse After Every Swim
This is the single most useful habit you can build. After swimming, rinse your trunks in fresh, cool water to remove salt, chlorine, sand, and sunscreen residue before it has a chance to sit in the fabric. A quick rinse under a shower or an outdoor tap is usually enough — you don't need a full wash after every swim.
Chlorine is effective at keeping pools clean, but it's not gentle on fabric over time. Saltwater behaves similarly: left to dry in the fibers, it can leave residue behind. A rinse that takes less than a minute prevents both from building up.
2. Don't Leave Wet Trunks Balled Up in a Bag
It happens to almost everyone: you leave the beach, toss damp trunks into a tote, and find them hours later in a warm, still-wet pile. Try to avoid making it a habit.
Trunks left wet and packed away can develop odor, stress the fabric, and leave the liner feeling less fresh. Colors can also bleed or fade faster when trapped against damp towels or other wet clothing. If you can't dry them right away, at least shake out any sand, rinse them if possible, and avoid sealing them in plastic for long stretches. Swimwear is made to get wet — it isn't made to stay trapped and damp all day.
3. Wash Gently, and Only When Needed
You don't need to machine wash your trunks after every quick swim. When they do need a deeper clean, keep it gentle:
- Use cold water
- Choose a gentle cycle
- Use a mild detergent
- Wash with similar colors
- Avoid heavy items like jeans, towels, or hoodies in the same load
Heavier laundry can rub against swimwear and cause unnecessary wear, and towels in particular can be rough on softer performance fabrics and liners.
If you machine wash regularly, it's worth using a Guppyfriend washing bag. It protects details like drawstrings, embroidery, and stitching from friction in the wash, and it also catches the tiny microfibers that any fabric — recycled or virgin — can shed during a wash cycle, so they don't end up going down the drain and into waterways. It's a small addition to laundry day that pays off both for the shorts and for what leaves your washing machine.
4. Avoid Bleach and Harsh Detergents
Keep bleach away from swimwear entirely. It can damage fabric, fade colors, weaken fibers, and change the feel of the material. Harsh detergents can be similarly aggressive, especially on a fabric designed to feel soft and lightweight.
A mild detergent does the job. The goal isn't to strip the shorts completely — it's to lift salt, chlorine, sunscreen, and everyday residue without breaking down the fabric underneath.
5. Skip the Fabric Softener
Fabric softener sounds like it should help, but it works against performance swimwear. Many quick-dry fabrics rely on an open, breathable structure to dry fast and feel light. Fabric softener can coat the fibers, which can reduce breathability and slow down drying time.
If your trunks are already made from a genuinely soft fabric, you don't need softener in the first place — the feel should come from the material and construction, not from a laundry additive.
6. Air Dry Instead of Using a Dryer
Air drying is the best way to dry swim trunks. After rinsing or washing, shake them out gently and hang them somewhere with good airflow — a drying rack, a shower rail, or a shaded balcony all work well. Avoid wringing or twisting them aggressively, which can stretch the fabric and stress the seams.
Skip the tumble dryer altogether. High heat can damage swimwear, weaken elastic, affect the liner, and shorten the life of the fabric. A well-made pair of quick-dry trunks shouldn't need a dryer in the first place — give them air and a bit of time instead.
7. Dry in the Shade When You Can
Sunlight is part of summer, but shade is better for drying. Long stretches of direct, intense sun can gradually fade color and weaken fibers, especially if the shorts are still carrying salt or chlorine. Drying them in the sun for a little while at the beach is fine; for regular care at home, a shaded, airy spot is the better habit. Airflow does the real work — heat isn't necessary.
8. Watch for Sunscreen and Body Oils
Sunscreen is essential, but some formulas — mineral sunscreens especially — can leave marks on fabric, particularly darker colors. Apply sunscreen before putting your trunks on when you can, and give it a minute to absorb before sitting down. If sunscreen does get on the fabric, rinse the shorts after use and wash gently if a mark remains. It's a normal part of summer wear, not something to avoid — just something to stay aware of.
9. Shake Out Sand Before Washing
Sand seems harmless, but it's rough on both fabric and washing machines. Before washing, shake your trunks out properly, turn any pockets inside out, and rinse the liner and waistband area if needed. Sand tends to hide in seams and mesh, then rub against fabric during the wash cycle — a quick shake-out first keeps that from happening.
10. Store Them Only When Completely Dry
Before putting your trunks away, make sure they're fully dry. Storing them damp is the fastest way to get odor or mildew, and it leaves the liner feeling less fresh the next time you wear them. Once dry, fold them loosely and store in a cool, dry place — not a hot car, a gym bag, or a still-damp beach tote.
11. Rotate Between Pairs
If you swim often, having a second pair to rotate in gives each one time to fully dry and rest between wears, rather than going straight back into salt or chlorine while still recovering from the last swim. It's a small habit, but it adds up over a season of regular use.
How Often Should You Wash Swim Trunks?
It depends on how you used them. A quick ocean dip followed by a good rinse usually doesn't need a full wash right after. A full day of sunscreen, sweat, sand, and saltwater probably does.
If you take one rule from this guide, make it this: rinse after every swim, wash after heavy use, and wash before storing shorts away for an extended period. Rinsing is the daily habit. Washing is the reset.
How Blauw Designs for Longer Wear
The Blauw Short is built with OceanKnit™ fabric, designed to feel soft against the skin, dry in approximately 7 minutes, and move comfortably from the water into the rest of the day. A tailored 5-inch inseam, lightweight micro-mesh liner, and minimalist design make it easy to wear well beyond the beach or pool — and swimwear you actually want to keep wearing tends to get the kind of basic care that makes it last.
Our advice stays the same regardless of which pair you own: rinse after every swim, wash gently when needed, and let your shorts air dry. That small routine protects the fabric, the liner, the fit, and the feel over time.
Final Thoughts
Swim trunks don't need high-maintenance treatment, but they do need the basics. Rinse out salt and chlorine, don't leave them wet in a bag, wash gently, skip bleach and fabric softener, air dry in the shade, and store them only once they're dry. Do that consistently, and a good pair of swim trunks will look better, feel better, and last considerably longer.
FAQ: How to Care for Swim Trunks
Should you wash swim trunks after every use?
Rinse them after every use, especially after saltwater or chlorine. A full machine wash isn't always necessary — rinsing alone protects the fabric and liner in most everyday situations.
What's the best way to wash swim trunks?
Cold water, mild detergent, and a gentle cycle. Hand washing works well for extra care. Avoid bleach, fabric softener, hot water, and heavy laundry loads, and consider a mesh washing bag to reduce friction and catch shed microfibers.
Can swim trunks go in the dryer?
It's best to air dry them. Tumble dryers expose swimwear to heat and friction that can shorten the life of the fabric, liner, and elastic.
How do you make swim trunks last longer?
Rinse after swimming, wash gently and only when needed, avoid harsh detergents and softeners, air dry in the shade, and never leave them wet in a bag for long periods.
Why do swim trunks fade?
Repeated exposure to chlorine, saltwater, sunlight, sunscreen, and harsh washing all contribute to fading. Rinsing after use and drying in the shade help preserve color.
How do you get chlorine out of swim trunks?
Rinse in cool, fresh water as soon as possible after swimming. For a deeper clean, wash gently with a mild detergent and air dry.
How should you store swim trunks?
Only store them once they're completely dry. Keep them in a cool, dry place, and avoid leaving them damp in a gym bag, beach tote, or hot car.
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