"Proper swimwear" is normally required, but there isn't really a standard definition for this, otherwise it would be stated. Recently, dress codes in many pools have been relaxed to allow for additional modesty. Many public swimming pools allow T-shirts in the water, but do not allow other street clothes into the pool.
Acceptable swimwear may include surf shorts made of a light fabric, and rash tops or swim shirts. T-shirts may be worn over swim wear when you're in the outdoor pools.
Some pool operators allow you to swim in clothes if you bring an extra set to swim in. This rule tries to maintain a clear distinction between clothes worn in the pool and street clothes worn outside. "Street clothes" are only allowed with special arrangement, like survival or lifesaving training.
The purpose of clothing rules is to minimise the bacterial load by ensuring
that nobody can thoughtlessly rinse their dirty clothes in the swimming pool.
Otherwise the pool chemicals would have to be monitored and topped up more often, "just to be on the safe side".
More chlorine means more stinging eyes and faster rotting of your swimwear.
Many pools only allow clothes made from "man-made" fibres that don't leak dye or lose filter blocking fluff. Make sure all clothes are unlined to avoid pockets where water or air gets trapped.
Lycra swim shirts, body suits and speed suits are considered swimwear and should therefore be acceptable in most pools. Check that the fabric is chlorine resistant.
Lightweight anoraks are often allowed for special training needs like lifesaving and resistance swimming.
Your swimming clothes should be well fitting and properly tucked in. Loose and baggy clothes may get caught on something, particularly on slides.
Clothes must not restrict movement or cause significant drag in the water, again for safety. The idea that "resistance builds stamina" is evidently considered inappropriate by some safety officers. Educate them.
Avoid exposed metal rivets or fasteners, because they could cause injury to other swimmers or scratch and damage the slides. Some "approved" Speedo "original swim shorts" have a small metal eyelet at the bottom of the back pocket, where it could easily cause scratches.
Clean T-shirts and 3/4 length shorts are alright, depending on the staff on duty.
People will probably not look twice if you choose to wear your T-shirt in a swimming pool.
Just ask and check the rules of the pool before swimming in your T-shirt.
Ask at the reception if you can wear special training clothes in the pool. Explain that you prefer modest swim clothes or want to do survival swimming or lifesaving training. Sometimes you have to ask for the pool manager.
Change into fresh swimming clothes on-site. They must be clean and colour-fast, no leakage of dye into the pool. The material has to be in good condition, not fraying or shedding fluff.
Go through the showers in these clothes before entering the pool. Taking a shower before swimming makes good hygiene sense. If you want to swim in clothes, the shower washes the fluff off. Make sure you rinse and soak them well. Dry spots show the staff you haven't taken a proper shower. Besides, it's great fun.
Pick up any clothes right away that you may have dropped to the pool bottom, as they may confuse the lifeguards. Large items of clothing floating in the pool can be mistaken as casualties and are also a hindrance for swimmers.
Clear away any clothes you currently don't need for your training in a safe place on the pool side, out the the way of other pool users.
Keep your clothes on in the shower after your swim to wash all the chlorine and other stuff out.
Rinse any waterproofs inside and out.
There's also a good reason to shower in your kit after gym class, swimming or other sports. If you ever washed dirty gym clothes, you know those clothes can be hazardous to your health. But it's not just the smell that can do you in.
Sweaty sports clothes are a prime breeding ground for bacteria and viruses. Those warm, moist clothes create a perfect environment for germs to grow, and those germs can make you sick.
The best advice for athletes who get sick repeatedly is: Take a shower to rinse your kit right after exercise. Wear clean clothes for your next workout or swim. This applies to anyone who gets wet, hot or sweaty.
Salt, sweat or chlorine can rot your kit. If you have the chance, take a shower in your exercise or swimming clothes after a workout or swim, even if that option isn't popular among other people around you. Shampoo your hair and clothes. Lycra doesn't like shampoo.
Rinse off well and hang your clothes out to dry.
Don't leave sweaty gym clothes in your locker until they can practically walk home by themselves.
I have been to several public indoor pools wearing my 3/4 length tracksuit bottoms, which are nearly down to my ankles. None of the staff questioned me why I was wearing them for swimming. They are clearly classed as swimwear.
I was not the only one in the pool with these, several other guys looked great in their T-shirts and 3/4 length shorts.
Now my friends and I always balance the look and swim with a T-shirt, or the occasional sweatshirt or hoodie.
The local pool in my area offers separate Muslim swimming sessions for men and women. Modest swimming clothes are mandatory and must cover from shoulders to below the knees. Most swimmers wear long pants or jeans with a sports shirt, hoodie or anorak. Tracksuits and jogging suits are also very popular.
My friends and I love swimming in clothes, so these sessions are ideal for us. We bring one or two sets of clothes for swimming which we put on in the changing rooms.
Nylon tunics with long pants are available at the reception for anyone who didn't bring adequate swimwear. We bought a few of those as they look cool and feel nice in the water.
It is always a very colourful scene in the pool with everybody swimming in clothes. Before we're allowed into the pool we have to wear our clothes under the shower for hygiene reasons. Then we go into the pool and play around like crazy.
After swimming a while, we get out, change into another dry set of swimming clothes, and eat in the restaurant.
Then we rest a bit before we jump back into the pool fully clothed.
All this is huge fun.