Rinse UPF swimwear in cool, fresh water right after every swim. Hand wash it with a mild detergent only when it needs more than a rinse. Press out the water without wringing, then dry it flat or on a line in the shade. Skip hot water, bleach, fabric softener and the dryer. Those steps protect the fabric’s weave and stretch, and both affect how much UV the garment blocks.
This guide covers the full routine for kids’ swimwear, the mistakes that wear out fabric early, and the signs that a suit or rash guard should be replaced.
TL;DR
- Rinse in cool fresh water after every swim. This removes chlorine, salt and sunscreen before they sit in the fibers.
- Deep wash only when needed: cool water, mild detergent, by hand or on a gentle cycle in a mesh bag.
- Air dry in the shade. Heat from dryers and long sun exposure breaks down elastic and fibers.
- Replace any piece that is thin, faded, frayed or stretched out. A damaged weave lets more UV through.
- UPF clothing is one layer. Pair it with a hat, sunglasses and sunscreen on exposed skin.
Table of Contents
- Why washing matters for UPF protection
- Quick reference: do and don’t
- Step 1: Rinse after every swim
- Step 2: Wash by hand when it needs a deeper clean
- Step 3: Dry it the right way
- What shortens the life of UPF swimwear
- When to replace UPF swimwear
- Our view: care is part of the protection
- Shop BANZ UV swimwear for kids
- Common questions about washing UPF swimwear
- Sources
Why washing matters for UPF protection
UPF measures how much ultraviolet radiation a fabric blocks. According to the Skin Cancer Foundation, a UPF of 50 or more rates as excellent, and UPF 50+ clothing blocks at least 98% of the sun’s UVA and UVB rays. A standard white cotton T-shirt, by comparison, may only reach a UPF of about 5.
That rating depends on the condition of the fabric. Three things change it most:
- Weave density. Tight fabric blocks more UV. Stretching, thinning and pilling open the weave.
- Fit and stretch. Fabric pulled tight across the body lets more UV through. Elastic that is worn out and overstretched shows this first.
- Wetness. The Skin Cancer Foundation notes that wet or strained fabric lets significantly more UV radiation through than dry fabric. Dry kids’ swimwear off between swims when you can, and keep sunscreen on any skin that gets exposed.
Washing affects the first two. Harsh detergent, heat and friction wear down fibers and elastic. Chlorine, salt and sunscreen left in the fabric do the same, more slowly.
What the research says about repeated washing
A 2023 study on routine laundering and UPF values tested seven commercially available sun-protective garments, washed in cold water with commercial detergent. The results varied by garment. After 50 washes, some items lost 70% to 78% of their UPF value, while others held their protection through extensive use.
The difference comes down to how the protection is built. UV blocking that is part of the fiber and weave tends to last. A topical chemical treatment is more likely to wash off. For you as a parent, the practical point is simple: read the care label, follow it, and do not assume every UPF label means the same durability.
Quick reference: do and don’t
| Step | Do | Don’t |
|---|---|---|
| After swimming | Rinse in cool, fresh water right away | Leave it balled up in a wet towel or plastic bag |
| Washing | Hand wash with mild detergent in cool water | Use hot water, bleach or fabric softener |
| Machine option | Gentle cycle, mesh bag, wash with similar items | Wash with zippers, Velcro or rough fabrics |
| Drying | Lay flat or hang in the shade | Use the dryer or dry in direct sun |
| Sunscreen | Apply 20 minutes before dressing | Rub sunscreen directly onto the fabric |
| Storage | Store clean and fully dry | Store damp or in direct sunlight |
Step 1: Rinse after every swim
A rinse is the most useful habit, and it takes one minute. Chlorine, salt and sweat start breaking down elastic fibers as soon as the suit dries with them still in it.
- Rinse the garment in cool, fresh tap water as soon as your child is out of the pool or ocean.
- Run water through the fabric until it runs clear, including seams, cuffs and the inside of the swim diaper or lining.
- Press the water out with your hands. Do not twist or wring.
- Lay it flat or hang it up in the shade. Do not leave it in the tote bag for the drive home if you can avoid it.
The most common mistake is the damp towel bundle. A wet suit rolled in a towel or bag stays dark and damp. Chlorine, salt and sweat keep working on the elastic, and mold can grow. If you can’t rinse at the pool, bring a bottle of fresh water and a large resealable bag for the trip, then rinse at home as soon as you arrive. Give the suit the full rinse and dry it as soon as you get home.
When a rinse is enough
For a short pool session or a day of splashing, a rinse is usually enough. Save a full wash for when the suit smells, looks dirty, or has been in a lot of sunscreen, sand or sweat. Frequent or harsh washing speeds up wear on the fabric, so less is better here.
Step 2: Wash by hand when it needs a deeper clean
Hand washing is the gentlest method and takes about five minutes.
- Fill a clean sink or basin with cool water.
- Add a small amount of mild detergent. Skip bleach, stain-removing boosters and fabric softener.
- Submerge the garment and swish it gently for a few minutes. Work lightly on collars, underarms and any sunscreen marks with your fingers.
- Drain the basin and rinse in cool, fresh water until no suds remain.
- Press the water out between your palms. Roll it in a clean, dry towel if you need to take out more water. Do not wring.
Using the washing machine
If the care label allows machine washing, protect the garment:
- Put it in a mesh laundry bag.
- Choose the gentle cycle and cool water.
- Wash it with other swimwear or soft items. Zippers, Velcro, buttons and rough fabrics snag and pill the weave.
- Take it out as soon as the cycle ends.
Always check the care tag first. The tag on each garment is the manufacturer’s instruction for that fabric and takes priority over any general advice, including this guide.
For more on keeping sun clothing working across many washes, see our UPF 50+ clothing care guide for parents.
Step 3: Dry it the right way
Heat is hard on stretch fabric. A hot dryer can damage elastic and any coatings on the fabric.
- Lay the garment flat on a clean towel or hang it over a line or rack.
- Choose a shady, ventilated spot. Long hours in direct sun can fade and weaken fabric.
- Turn it over once so both sides dry.
- Do not store it until it is fully dry.
If your child swims every day, rotate between at least three suits. Fibers need time to recover their shape between wears, and you will always have a dry one ready.
What shortens the life of UPF swimwear
Beyond washing, a few everyday habits wear out fabric faster than you would expect.
Sunscreen on the fabric
Sunscreen chemicals can stain fabric and wear on its integrity when applied directly onto it. Put sunscreen on your child at least 20 minutes before they get dressed, so it absorbs into the skin. Use it on skin the garment does not cover: face, neck, hands, feet and the legs and arms of short-sleeve styles.
Do not skip reapplying. MD Anderson recommends reapplying sunscreen at least once every two hours, and more often when playing in the water or sweating. When you reapply, keep it off the swimwear as much as you can. Sunscreen that lands on the fabric is the main cause of yellow marks. Rinse the marks out as soon as you can.
Rough surfaces
Sliding down the pool edge, sitting on concrete or crawling on rough decking pills the fabric. Pilling thins the weave and lowers the UV protection. Bring a towel for your child to sit on at the pool deck, and check the seat and the bottom of the suit more often than the rest.
Chlorine, salt and hot tubs
Chlorine and salt water are the main reasons swimwear elastic fails early. Hot tubs are harder still because of heat and chemical concentration. The fix is the same: rinse promptly, wash gently, dry in the shade.
Heat and sunlight in storage
A hot car trunk or a window sill is a poor storage spot for swimwear. Keep it in a dry drawer or bag once it is clean and fully dry.
When to replace UPF swimwear
Proper care can extend the life of UPF swimwear to roughly 30 to 40 washes, or one to two years of moderate use. Poorly maintained gear can lose performance much sooner. Kids also outgrow suits fast. A suit that is too small stretches across the body, and stretched fabric lets more UV through.
Replace the garment when you see any of these:
- The fabric looks thin or see-through, especially when wet.
- The elastic is loose, overstretched or no longer holds its shape.
- Colors have faded noticeably.
- The weave is frayed or heavily pilled.
- The suit no longer fits properly: tight across the shoulders or too short in the torso.
The Skin Cancer Foundation advises replacing clothing that is noticeably thin, frayed or overstretched, because its rating is compromised. If you aren’t sure, hold the dry fabric up to a bright window. If you can see light clearly through it, the weave has worn.
Our view: care is part of the protection
We started BANZ® because a family in Australia could not find suitable protection gear for their own children. Since then, we have heard from over 2 million families across six continents. The same question comes up often: how do I keep this working?
Our answer is that UPF 50+ is a rating for a garment in good condition, and good condition is largely in your hands. A well-made suit can lose its stretch and its weave if it sits wet in a bag for a weekend. We would rather you spend one minute rinsing than replace a suit mid-summer.
We also hold to a simple rule: clothing is one layer of sun safety. Pair swimwear with a hat, UV-rated sunglasses and sunscreen on exposed skin. Our guide to swim shirts and sunscreen explains how the two work together. Follow the care label on every piece, and replace what has worn out.
— Shari M. Murphy
Shop BANZ UV swimwear for kids
If your child’s current suit is thin, stretched or outgrown, it is time to replace it. Our Feel No Flare™ UV Swimwear starts from $15. For longer coverage at the pool or beach, see the Girls 2 Long Sleeve Rashguard Set. For babies, the Baby Swim Diaper Ruffle Skirt is a swim-ready option. You can also browse the full BANZ collection for sun hats, sunglasses and goggles. Our UV protection swimsuit guide helps you pick the right style.
Common questions about washing UPF swimwear
Does washing remove UPF protection?
It can, depending on how the garment is made and how it is washed. A 2023 laundering study found that some garments lost 70% to 78% of their UPF value after 50 washes, while others kept their protection. Cool water, mild detergent and limited washing reduce the wear. Follow the care label.
Can I put UPF swimwear in the dryer?
It’s best not to. Heat damages elastic and can break down fibers and coatings. Air dry the garment flat or on a line in the shade. If the care label on your specific garment allows machine drying, follow it, but air drying is the safer choice for any stretch fabric.
How often should I wash my child’s UPF swimsuit?
Rinse it in cool, fresh water after every swim. Do a full hand or gentle machine wash when it smells, looks dirty or has sunscreen marks. Washing more often than that adds wear without much benefit.
Is UPF swimwear still protective when wet?
Protection drops when fabric is wet or stretched. The Skin Cancer Foundation notes that wet or strained fabric allows significantly more UV through. That is one reason to use a hat, sunglasses and sunscreen on exposed skin along with UPF clothing, and to choose a suit that fits without pulling tight.
How do I get sunscreen stains out of a swimsuit?
Rinse the stain in cool water as soon as you see it, then hand wash with a mild detergent. Avoid bleach. To prevent stains, apply sunscreen to your child at least 20 minutes before dressing and keep reapplication off the fabric.
Sources
- Sun-Protective Clothing, The Skin Cancer Foundation
- The Impact of Routine Laundering on Ultraviolet Protection Factor (UPF) Values, PMC
- UPF, sun protection and clothing: 7 things to know, UT MD Anderson