New York City public pools open on Thursday, just in time for the holiday weekend and accompanying 90 degree weather. For the next three months, the entire city has access to the 53 outdoor pools scattered across the five boroughs, each as free and heat-relieving as the last. "But aren't they kinda gross?" you ask, pointing to a study from those anti-swimming nerds over at the CDC. Common misconception! Each of the city's public pool's is checked regularly by both the Parks Department and Department of Health, and independent tests suggest that the water is cleaner than the city's private pools. (Isolated incidents aside.)

But before you take the plunge, it's important to familiarize yourself with the sometimes-confusing rules and etiquette of the pool. You should consult the official guidelines here, but we also reached out to the Parks Department for a quick refresher on what public pool-bound New Yorkers most need to know.

Lock It Up

The number one thing people forget to bring to the pool, according to Parks Department spokesperson Meghan Lalor, is a padlock. Even if you don't plan on storing your things inside a locker, these master or combination locks are required to enter any of the city's public pools—non-negotiable! If you forget to bring a lock, you will be turned away at the gate, with only the tears running down your face as refreshment. That said, if you find yourself lockless outside the John Jay Pool on the Upper East Side, I can confidently recommend visiting the adjacent bodega for a bailout (the cashier smiles knowingly, but says nothing about your inability to follow simple directions).

Dress The Part

"The other main thing people forget is the attire," Lalor tells Gothamist. That means a swimsuit, obviously, but also a white T-shirt. If you have a gray T-shirt, you will not be allowed on the pool deck. Same goes for the other colors, because dye can run in the pool. However, you WILL be allowed in with no T-shirt at all. Men must also wear mesh-lined bathing suits, and swim caps are encouraged but not required. To summarize: You don't have to wear a shirt to the pool, but if you do wear a shirt to the pool it has to be white, and you have to wear a normal bathing suit.

Forget The Morning Paper

Feel free to bring a book, but no newspapers. "The issue here is that the pages tend to blow around and end up in the pool, so no unbound periodicals," Lalow explains. "We want you to read, but only books and magazines on the pool deck." Fair enough. You're also allowed to read blogs, just FYI.

Don't Pee, Please

Here's the deal: The last time a biochemist checked, fancy rooftop pools were filled with waste-borne coliform bacteria, while the water in the city's public pools was "pristine." Let's keep it that way, so that we can make fun of rich people for being gross as we float through our spotless proletarian basins.

Pack Light

It's crucial that you save the beach balls and beach blankets and beach chairs for...the beach. These items aren't allowed on pool decks, which tend to get pretty busy on hot days. Neither is booze or food, by the way, though a few of the public pools—like the one in Astoria—do have concession stands serving up burgers and hot dogs. And don't worry about sunscreen; this year, the Park's Department installed sunscreen dispensers (SPF 50) at every single one of the city's outdoor pools. So just bring yourself and your back sweat, and don't overthink it. As Lalor says, "Come with your towel in hand and swimsuit on already—that's all you need to enjoy the pool." (AND A LOCK!)