We design swimwear that's meant to last — but even the best bikini needs proper care. Every piece we create at KOH SWIM is engineered for tropical conditions: chlorine resistance, salt water durability, quick-dry performance. But the truth is, what happens after you swim matters just as much as the fabric itself.

Your swimwear faces a hostile environment every time you wear it. Chlorine, salt water, sunscreen, UV radiation, and heat are all actively breaking down the fibres in your bikini from the moment you put it on. According to the Swimwear Association, the average swimsuit lasts only 3–6 months without proper care. With the right routine, you can extend that to 2–3 years — tripling the lifespan of every piece in your collection.

Source: Swimwear Association, swimsuit lifespan and care guidelines, 2025

We've tested every fabric blend, every wash method, and every storage technique in Phuket's extreme tropical conditions — 34°C heat, 80% humidity, daily ocean swims, and weekly pool sessions. This guide distils everything we've learned into a practical, actionable routine that takes less than two minutes per day.

The difference between a swimsuit that lasts one holiday and one that lasts three years isn't the price tag — it's the 30 seconds you spend rinsing it after each swim.

The 3 Enemies of Swimwear

Before we get into the care routine, it helps to understand exactly what's destroying your swimwear. Three substances do the vast majority of the damage, and each attacks your bikini's fabric in a different way.

1. Chlorine

Chlorine is the single most destructive substance your swimwear encounters. Pool water typically contains 1–3 parts per million of free chlorine, and that's enough to systematically break down the elastane (Lycra/spandex) fibres that give your swimsuit its stretch, shape, and fit.

According to Speedo's fabric research, chlorine can degrade elastane fibres by up to 50% over 100 hours of pool exposure. That means if you swim in a pool for one hour a day, your bikini could lose half its stretch within three to four months. The damage is cumulative and irreversible — once elastane fibres are broken, no amount of care will restore them.

Source: Speedo, fabric performance and chlorine resistance research, 2024

Chlorine also causes colour fading, particularly in dark and vibrant shades. The bleaching action that keeps pool water clean also strips dye from swimwear fabric. A black bikini that's spent a summer in the pool often emerges looking washed-out grey by September.

2. Salt Water

Salt water is less aggressive than chlorine, but it introduces a different problem. When salt water dries on swimwear fabric, the salt crystallises and embeds itself between the fibres. These microscopic crystals act like tiny abrasives, causing stiffness, roughness, and gradual fibre degradation with each wear.

If you've ever pulled on a bikini that dried stiff and scratchy after a beach day, that's salt crystal damage. The fabric isn't ruined yet — a proper fresh water rinse dissolves the crystals and restores softness — but leaving salt in the fabric repeatedly accelerates wear and shortens the garment's lifespan.

The good news: salt water is far less destructive than chlorine. If you primarily swim in the ocean rather than the pool, your swimwear will last longer by default. A dedicated "pool suit" and "beach suit" rotation is one of the simplest ways to extend the life of your entire collection.

3. Sunscreen

Sunscreen is the sneakiest enemy of swimwear because the damage is cosmetic rather than structural — but it's often permanent. Chemical sunscreens containing avobenzone and oxybenzone react with fabric dyes and body oils to create stubborn yellow, orange, or brown stains that are extremely difficult to remove once set.

The staining happens at the molecular level. Avobenzone, the most common UVA-blocking ingredient in chemical sunscreens, oxidises when exposed to UV light and produces a yellow-brown compound that bonds to fabric fibres. White and light-coloured swimwear is particularly vulnerable — a single application of chemical sunscreen can leave permanent marks on a white bikini.

Mineral sunscreens based on zinc oxide and titanium dioxide are significantly safer for swimwear. They sit on top of the skin rather than absorbing into it, which means less transfer to fabric. They can leave white residue on dark swimwear, but this washes out easily with a fresh water rinse — unlike chemical sunscreen stains, which often don't.

How to Wash Your Swimsuit (Step by Step)

Proper washing is the foundation of swimwear care. Get this right and your bikini will outlast most of your other summer clothing. Get it wrong and you'll be shopping for replacements every season.

Step 1: Rinse Immediately After Every Swim

This is the single most important step in swimwear care, and it takes 30 seconds. As soon as you finish swimming, rinse your swimsuit in cool fresh water. Not warm, not hot — cool. This removes the majority of chlorine, salt, sunscreen residue, and body oils before they have a chance to bond with the fabric fibres.

If you're at the beach and don't have access to a tap immediately, bring a bottle of fresh water in your beach bag. Even a quick splash is better than nothing. The goal is to prevent chlorine and salt from sitting on the fabric as it dries — that's when the real damage happens.

Step 2: Hand Wash with Gentle Detergent

After every 2–3 wears (or after every pool swim), do a proper hand wash. Fill a basin with cool water and add a small amount of gentle detergent — ideally a dedicated swimwear wash, but a mild hand soap or baby shampoo works too. Gently agitate the swimsuit in the water for 2–3 minutes, paying attention to areas that accumulate sunscreen and body oils (underarms, neckline, seat).

Never use regular laundry detergent. Standard detergents contain harsh surfactants, optical brighteners, and enzymes that are designed for cotton and polyester clothing. On swimwear's delicate elastane blend, these chemicals accelerate fibre breakdown and can cause colour fading.

Step 3: Rinse Thoroughly

Rinse the swimsuit under cool running water until all detergent is gone. Soap residue left in the fabric attracts dirt and can cause skin irritation on your next wear.

Step 4: Press — Never Wring

Lay the swimsuit flat on a clean towel. Fold the towel over and press gently to absorb excess water. Never wring, twist, or stretch your swimwear to remove water. Wringing distorts the fabric's structure, stretches elastic, and can permanently misshape cups and padding.

What Never to Do

• Never machine wash. The agitation and spin cycles destroy elastane. According to Speedo's fabric care guidelines, machine washing can reduce swimwear lifespan by up to 60%.
• Never use fabric softener. Softener coats fibres with a waxy residue that reduces stretch recovery, traps odours, and repels moisture — the opposite of what you want from swimwear.
• Never use bleach. Even on white swimwear, bleach attacks elastane and causes irreversible yellowing within a few uses.
• Never soak for extended periods. More than 30 minutes of soaking can loosen dyes and weaken elastic. Quick, gentle washes are better than long soaks.

Source: Speedo, official fabric care and washing guidelines, 2024

How to Dry Your Swimsuit

How you dry your swimwear is almost as important as how you wash it. Heat and UV light are both actively damaging to elastane, so the drying method matters.

The Correct Method

1. Press in a towel. Lay the swimsuit on a clean, dry towel. Roll the towel up with the swimsuit inside and press gently to absorb moisture. Unroll.
2. Lay flat in shade. Place the swimsuit flat on a dry surface — a drying rack, a clean towel, or even the edge of a bathtub. Choose a spot with shade and airflow.
3. Allow to air dry completely. In Phuket's humidity, drying takes 2–4 hours in shade with good airflow. In drier climates, it can be faster. The swimsuit should be completely dry before you store it or wear it again.

What Never to Do

• Never tumble dry. The heat in a dryer is the fastest way to kill elastane. A single tumble dry cycle can cause more damage than a month of proper wear. The heat causes fibres to contract, lose elasticity, and become brittle.
• Never hang dry in direct sun. UV radiation fades colours and degrades fabric — the same UV that damages your skin is damaging your swimwear. Always dry in shade.
• Never hang by the straps. Gravity pulls water down through the fabric, concentrating weight at the strap attachment points. Over time, this stretches straps permanently. Always lay flat.
• Never drape over a metal railing. Metal railings in tropical climates get extremely hot in the sun and can scorch or discolour fabric on contact. Rust from metal can also leave permanent stains.

How to Remove Stains

Even with perfect care, stains happen. Here's how to deal with the most common swimwear stains — and when prevention is genuinely the only cure.

Sunscreen Stains

Sunscreen stains are the most common and most frustrating swimwear stain. The yellow-orange marks left by chemical sunscreens (especially avobenzone-based formulas) can appear within hours and set permanently within days if untreated.

Treatment: Mix equal parts white vinegar and baking soda into a paste. Apply the paste directly to the stained area. Let it sit for 30 minutes. Then hand wash the entire garment in cool water with gentle detergent. Repeat if necessary. For stubborn stains, a small amount of oxygen-based stain remover (like OxiClean) can help, but test on an inconspicuous area first.

Prevention: Apply sunscreen 15–20 minutes before dressing. Let it absorb fully. Use mineral sunscreen (zinc oxide, titanium dioxide) with white or light-coloured swimwear. Rinse swimwear immediately after removing it.

Chlorine Smell

That persistent chemical smell after pool swimming comes from chloramines — compounds formed when chlorine reacts with sweat, body oils, and urine in the pool. They cling to fabric and can be difficult to remove with water alone.

Treatment: Soak the swimsuit in a basin of cool water with 2 tablespoons of white vinegar for 30 minutes. The acetic acid neutralises the chloramines. Follow with a normal hand wash. If the smell persists, add 1 tablespoon of baking soda to the soak.

Colour Fading

Once colour has faded, there's no way to restore it. Fading is caused by chlorine exposure, UV radiation, and harsh detergents — all of which strip dye from fabric fibres at the molecular level. Prevention is the only cure: rinse immediately after every swim, always dry in shade, never use bleach or strong detergent, and rotate between multiple suits to reduce per-garment exposure.

Sand

Sand is deceptively tricky. Your instinct is to brush it off immediately, but rubbing wet sand against swimwear fabric is like using fine sandpaper — it abrades the surface fibres and can cause pilling.

Treatment: Let the swimsuit dry completely. Once dry, the sand releases easily — shake the garment firmly, then brush off remaining grains with your hand or a soft-bristled brush. Rinse in fresh water afterward to remove any remaining particles from seams and folds.

How to Store Swimwear

Proper storage is the final piece of the care puzzle. It matters less during a one-week holiday (when you're wearing and washing daily) and more for long-term storage between seasons or between trips.

• Lay flat or fold loosely in a drawer. Never ball up swimwear or stuff it into tight spaces. Compression creates permanent creases and distorts the shape of cups and padding.
• Store completely dry. This is critical in tropical climates like Phuket, where humidity creates ideal conditions for mildew. Even a slightly damp swimsuit can develop mould within 24–48 hours in tropical humidity. Make sure the garment is 100% dry before it goes in a drawer.
• Keep padding and cups shaped. If your bikini top has removable cups or moulded padding, keep them in their correct shape during storage. Stuff with tissue paper if needed. Flat, unsupported cups can warp over time.
• Separate from other clothing. Store swimwear away from garments with zippers, hooks, Velcro, or rough textures that can snag delicate swimwear fabric. A dedicated drawer section or a soft fabric pouch works well.
• Rotate between 2–3 suits. If you swim regularly, rotating between multiple swimsuits extends the life of each piece significantly. Elastane needs 24–48 hours to fully recover its stretch after a swim. Wearing the same suit two days in a row means the fibres never fully reset, leading to faster stretch-out and shape loss.

KOH SWIM Fabric Technology

We don't just sell swimwear — we obsess over the fabric it's made from. Every KOH SWIM piece is built with materials specifically selected to withstand the conditions our customers face in Phuket and across Southeast Asia.

Polyamide-Elastane Blend (80/20)

Our core fabric is an 80% polyamide (nylon) and 20% elastane blend. We chose this ratio after extensive testing in Phuket's conditions because it delivers the best combination of durability, stretch, shape retention, and comfort. Polyamide is inherently more resistant to chlorine and salt than polyester, while 20% elastane provides the smooth, compressive fit that holds its shape after hundreds of wears.

UPF 50+ Sun Protection

Every piece in our collection provides UPF 50+ sun protection, blocking over 98% of the sun's UV radiation. This matters in Phuket, where the UV index routinely hits 11–12 — classified as "extreme" by the World Health Organization. The UPF rating is built into the fabric weave, not applied as a coating, so it doesn't wash out over time. However, UV still degrades fabric gradually — which is why drying in shade is essential even for UV-rated swimwear.

Source: World Health Organization, UV Index guidelines and classification

Quick-Dry Performance

Phuket's humidity sits between 70–85% for most of the year. Standard swimwear can take 6–8 hours to air-dry in those conditions. Our polyamide-elastane blend is engineered to dry in 2–4 hours in shade with airflow — fast enough to wash after a morning swim and have a dry suit ready for an evening beach club session.

Recycled Polyamide

Select pieces in our collection use recycled polyamide (regenerated nylon made from post-consumer waste like fishing nets and fabric scraps). We've tested recycled polyamide extensively against virgin polyamide and found no measurable difference in durability, stretch recovery, or colour retention. The sustainable option performs identically under tropical conditions.

According to Grand View Research, the global swimwear market reached $28.5 billion in 2025, with sustainable fabrics being the fastest-growing segment. We're committed to expanding our recycled fabric range as supply chains mature, without compromising the performance our customers expect.

Source: Grand View Research, Global Swimwear Market Report, 2025

Our Products

Every KOH SWIM piece uses the fabric technology described above. Explore our collection:

• Bikinis — Our bestselling category, designed for beach and beach club wear
• One Pieces — Elegant silhouettes with the same premium fabric
• Cover-Ups — Lightweight resort wear for beach-to-bar transitions
• New Arrivals — The latest additions to our tropical-ready collection

The 30-Second Post-Swim Routine

Everything in this guide boils down to one simple routine. If you remember nothing else from this article, remember this. It takes less time than reapplying sunscreen, and it triples your swimwear's lifespan.

That's it. Five steps, 30 seconds of active effort. Do this consistently and a quality swimsuit — like any piece from our collection — will last you 2–3 years of regular tropical use instead of 3–6 months.

When to Replace Your Swimsuit

Even with perfect care, every swimsuit has a finite lifespan. The elastane fibres that give swimwear its stretch and shape gradually break down through use, washing, and environmental exposure. Here are the signs that it's time for a new suit.

• Pilling: Small balls of fibre on the fabric surface, especially in high-friction areas like the seat and inner thighs. Pilling means the surface fibres are breaking down.
• Sagging elastic: If the waistband, leg openings, or bikini band no longer sit snugly against your body, the elastane has lost its recovery. The suit won't stretch back to shape.
• See-through fabric: When the fabric becomes translucent — particularly when wet — it means the fibres have thinned from wear and UV degradation. Time to retire this piece.
• Faded colour: Significant colour fading indicates that chlorine, UV, or harsh washing has broken down the fabric dyes. While cosmetic, fading usually accompanies structural degradation.
• Stretched straps: If straps no longer hold their shape or need constant adjustment, the elastane in those areas is exhausted. Straps are often the first part of a bikini to fail.
• Warped cups or padding: Cups that have lost their shape, padding that clumps or shifts, or moulded sections that have flattened — these indicate the structural elements of the garment have degraded beyond recovery.

If you notice two or more of these signs, your swimsuit has done its job — it's time for a replacement. A well-cared-for bikini from a quality brand should give you 2–3 years before you reach this point.

Frequently Asked Questions

How often should you wash a swimsuit?

Rinse your swimsuit in cool fresh water after every single swim — this is the most important care step. A full hand wash with gentle detergent should be done after every 2–3 wears, or after every wear if you've been in a chlorinated pool. Never let salt, chlorine, or sunscreen sit on the fabric overnight, as these chemicals break down elastane fibres and cause permanent damage.

Can you put swimwear in the washing machine?

No. Machine washing is one of the fastest ways to destroy swimwear. The agitation cycle stretches and distorts elastane fibres, the spin cycle damages elastic, and the heat from warm water degrades the fabric's stretch recovery. According to Speedo's fabric care research, machine washing can reduce a swimsuit's lifespan by up to 60%. Always hand wash in cool water with a gentle detergent or dedicated swimwear wash.

Source: Speedo, fabric care and washing best practices, 2024

How do you remove sunscreen stains from a bikini?

Create a paste of white vinegar and baking soda, apply it to the stained area, and let it soak for 30 minutes. Then hand wash in cool water with gentle detergent. Chemical sunscreens containing avobenzone and oxybenzone are the worst offenders for yellow-orange staining. To prevent stains, apply sunscreen 15–20 minutes before putting on your swimsuit and let it fully absorb. Switching to mineral sunscreens (zinc oxide, titanium dioxide) significantly reduces staining risk.

Does chlorine ruin swimsuits?

Yes, chlorine is the single most damaging substance for swimwear. It breaks down the elastane fibres that provide stretch and shape, causes colour fading, and makes fabric feel rough and brittle over time. To minimise damage, always rinse your swimsuit in fresh water immediately after pool use, and consider keeping a dedicated "pool suit" separate from your beach swimwear. Premium fabrics like KOH SWIM's polyamide-elastane blend are more chlorine-resistant than cheap polyester, but no fabric is completely immune.

How long should a good bikini last?

With proper care, a quality bikini made from premium nylon-elastane fabric should last 2–3 years of regular use. Without proper care, the average swimsuit lasts only 3–6 months. The key factors that determine lifespan are fabric quality (nylon-elastane blends last longer than polyester), care routine (rinsing after every swim, hand washing, flat drying in shade), and exposure to chlorine, which degrades fabric faster than salt water. Check out our body type guide to find a bikini worth investing in.

Should you rinse your swimsuit after every use?

Absolutely — rinsing in cool fresh water after every swim is the single most important thing you can do to extend your swimwear's life. It removes chlorine, salt crystals, sand, sunscreen residue, and body oils before they have a chance to degrade the fabric. This 30-second step can triple your swimsuit's lifespan. Keep a bottle of fresh water in your beach bag if you won't have access to a tap immediately after swimming.

How do you store swimwear properly?

Store swimwear completely dry, laid flat or loosely folded in a drawer. Never ball up swimwear or stuff it into tight spaces, as this creates permanent creases and distorts the shape. Keep padding and cups shaped by stuffing with tissue paper if needed. In tropical climates like Phuket, ensure swimwear is 100% dry before storing to prevent mildew. Store separately from clothing with zippers, hooks, or rough textures that can snag delicate swimwear fabric.

What fabric is most durable for swimwear?

An 80/20 polyamide (nylon) and elastane blend is the most durable fabric for swimwear. Polyamide is inherently more resistant to chlorine, salt, and UV than polyester, while the 20% elastane provides the stretch and shape retention needed for a comfortable fit. At KOH SWIM, we use this exact blend — it offers UPF 50+ sun protection, quick-dry properties, and maintains its shape after hundreds of wears. Recycled polyamide on our select pieces performs equally well in durability tests.

Written by The KOH SWIM Team

Phuket-Based Swimwear Brand · Est. 2025

We design, test, and wear swimwear in Phuket's tropical conditions every day. This care guide is based on our first-hand experience testing every fabric blend, wash method, and storage technique in 34°C heat and 80% humidity. We've seen what destroys swimwear and what makes it last — and we've built that knowledge into every piece we create.

Last updated: March 21, 2026