Public pools across the country are open for the summer season, but a recent survey could make you think twice about jumping in. According to the poll, almost half of swimmers admit to one or more behaviors that contribute to an unsanitary pool. And you’ve probably suspected as much, since the poll also shows 84 percent of us believe our fellow swimmers participate in unhygienic pool behavior.

THE DETAILS: The poll of 1,000 adults was conducted in late April and early May of this year by the Water Quality and Health Council, a body of scientific and other experts who advise the American Chemistry Council, an industry trade association. One in five respondents (17 percent) admitted to urinating in the pool, while almost eight in ten (78 percent) are convinced that their fellow swimmers are guilty of this act. Plus, about a third (35 percent) jump in without showering first, and three-quarters (73 percent) think other swimmers do the same. Even though most people seem wary of the hygienic standards of the swimmers around them, only 36 percent say that pool water cleanliness is on their mind when they take the plunge.

WHAT IT MEANS: Besides being just plain gross, filthy pool practices can lead to unsafe swimming conditions. Urine—as well as sweat and even sunscreen—contain nitrogen, which eats up a pool’s free chlorine. Free chlorine is what kills waterborne germs that could make you sick if ingested. So if too many people are peeing in the pool or diving in while sweaty, that could mean less chlorine’s available to wipe out nasty critters.

Even when chlorine levels are at proper levels, some illness-causing organisms can survive. For example, about two-thirds of all recreational water illnesses (or RWIs) are caused by Cryptosporidium, a chlorine-resistant microorganism that causes diarrhea. “Crypto can survive for as many as 10 days, even in a well-maintained pool,” says Michele Hlavas, epidemiologist in the Division of Parasitic Diseases for the Centers for Disease Control and Prevention (CDC). Which is why swimmers need to take on some of the responsibility for maintaining the safety of their pools. “Pool operators can’t do it all by themselves, as it’s the swimmers who bring the parasites into the water,” says Hlavas. “Swimmers have to get invested in keeping their pool clean and keeping themselves healthy.”

Here are a few tips to help you protect yourself, and other swimmers, from pool-related illness:

Don’t swim if you have diarrhea.

It sounds like common sense, but it bears repeating. And don’t send your kids to the pool if they’ve been having stomach problems.

Get to know your pool operator.

Showing you care about pool cleanliness can ensure that certain standards are met. Ask pool management about the training employees receive to operate and keep the pool clean, and how often they check the chlorine and pH levels of the water (both should be checked at least twice per day, more often on crowded days). You can also ask about how they fared on the most recent inspection, and how they’re correcting any problems that were uncovered.

Test the water yourself.

Inspectors aren’t on site every day, so what’s happening when they aren’t around? To find out, the CDC recommends purchasing easy-to-use testing strips at a local hardware or pool supply store, and measuring the pH and chlorine levels before swimming. The pH should be between 7.2 and 7.8, and there should be 1 to 3 parts per million of free chlorine in the water, according to CDC standards.

Don’t swallow pool water.

Don’t even swish it around in your mouth! You don’t have to swallow large amounts of contaminated water to get sick.

Shower before swimming.

Shower with soap and water before entering the pool so you don’t bring anything unhealthy in to the water. Don’t think you need to? Consider this fun fact: The average person has about 0.14 grams of feces on their bottom! Parents should also wash their children before swimming.

Check diapers often.

And make sure older children take regular bathroom breaks when swimming. It’s also important to change diapers in the bathroom, or other designated changing areas, and never on the pool deck or anywhere near the water.

Know the signs of a clean pool.

These include clear water, smooth pool sides (no sticky or slippery tiles), and no strong odors. A well-maintained pool should have little smell of chlorine, as a strong chemical smell can actually indicate a maintenance problem. You should also be able to hear the sounds of properly functioning pool equipment, such as pumps and filtration systems.

Many consider pool building as a summer project. But building during the cooler months brings a number of advantages. You will find that out-of-season swimming pool pricing can be very favorable indeed, providing some significant savings over the prices charged during the peak months. The availability of the swimming pool that you want is another factor that is influenced by the time of year. You’ll find it easier to find the exact pool that you want during the low-demand period of the year. Also, delivery and installation can be more favorable outside of the peak summer months.

The big advantage is that your new swimming pool will be ready to use as soon as the weather turns that little bit warmer in the spring. As soon as that warm weather appears you can be sure that your swimming pool supplier and installer will be immensely busy with a backlog of orders and installations to fulfill.

My advice to anyone who has been toying with the idea of having their own swimming pool installed in their garden is to gather a few quotes from reputable swimming pool suppliers now. You should be able to negotiate a substantial discount and get yourself a bargain swimming pool installed and ready for some summer fun.