First, read some Swimming pools safety measures:

Secure with appropriate barriers. It is best to install a fence four feet or taller around backyard pools and use self-closing and self-latching gates that open out of the pool.

Consider security alarms.

If your home faces directly onto the pool area, perhaps you should install a door alarm or self-closing door. Using a surface or underwater wave alarm will also give you more protection against accidental falls into the pool.
If you can’t find a child, always check the pool first. If a child falls into the pool, every second counts to prevent accidental drowning.

Empty portable pools when not in use.

Children can drown in even one inch of water. Make sure all inflatable, portable, and baby pools are empty and put them away immediately after use.
Remove toys from the pool when not in use. They may attract small children to the pool. It is best to keep them out of sight.

Have a safety kit on hand.

A first aid kit, including a pair of hair clippers, clothing, or a pool cover, should be available for use in an emergency. It is also recommended to have lifesaving equipment such as circular floats and life bars.
Stay away from pool drains . Limbs, hair, or clothing can become entangled if there is a faulty drain. If you suspect they may not be working properly, ask your service provider to inspect them. Pool Safety has detailed information on how to prevent being caught in a drain .Follow posted safety rules:

They generally include not running, pushing, or dunking others.

Oceans, lakes and rivers, Nothing near the lifeguards . The chance of drowning on a beach protected by trained lifeguards is estimated to be less than one in 18 million per year . Lifeguards can also advise you on the safest place to swim and which areas to avoid. If there is no lifeguard on duty, pack your own flotation device for emergencies. If you have a private pool and you want a lifeguard to supervise your pool or you want to be certified by lifeguard class , training and lifeguard courses you can also contact to American lifeguard events.
Stay within designated swimming areas . They are usually marked with ropes or buoys and are more likely to be free of algae, underwater rocky terrain, and other hazards.

Watch out for rip currents .

They are powerful, channeled currents of water that flow offshore and can occur on any beach with waves, including the Great Lakes. The United States Lifesaving Association has an extensive rip current survival guide .

Do not swim in contaminated water .

Pay attention to warning flags or alerts about contaminated water. Natural bodies of water do not receive chemical treatments like swimming pools, therefore they have a higher risk of spreading bacteria. Don’t drink the water and cover your nose when you submerge your head. Never swim when you are sick or have an injury and always shower after swimming. If you’re not sure if the water is clean enough to swim in, it’s best not to.

Know your limits .

Swimming in open water is very different from swimming in a pool. Cold water, rip currents, and other dangerous conditions can be challenging, even for the most experienced swimmers. If you are not sure of your limits, you should start slowly and not stray too far from the edge.

Be cautious

Avoid accidents and injuries by using your common sense to take certain precautions.

You should always:

• Stay close to shore and swim within designated areas.
• Walking into unknown waters , never dive. There may be rocks and other hazards just below the surface.
• Insist on wearing a life jacket if you or one of your companions is an inexperienced swimmer.
• Check the weather . Never swim when lightning is forecast.
• Take a break if you start to feel cold, tired or hungry.
• learn how to respond
• Prepare to respond quickly to these emergency situations:
• Unconscious Swimmer : If you can get the victim to shore safely, do it quickly. Begin CPR and call 911.
• Hypothermia : Prevent further drop in temperature. Warm victim slowly and seek medical attention immediately.
• Rip Current : Swim parallel to the shore until you have exited the rip current, then swim towards the shore. If you get tired, float on your back and kick. Knowledge is key when it comes to pool and water safety. Educating children from an early age, and staying informed, can lead to a lifetime of healthy and confident swimmers.