How Long After Shocking Pool Can You Swim (And Why)?

Exact Answer: 24 hours

The word ‘shocking’ refers to experiencing a shock due to an electrical current or short circuit. One could also describe a piece of news as shocking after hearing something new or entirely unexpected. However, when read with the word ‘pool’ it sounds amusing.

Shocking a pool has nothing to do with electricity or unexpected news, instead, it is a process that is done with pool water to increase the chlorine content in the water. It helps in breaking chloramines i.e combined chlorine that is harmful and bad, by quickly raising the chlorine level. It also helps in killing detrimental bacteria, algae, and other similar pathogens which might be present in the pool water.

How Long After Shocking Pool Can You Swim

How Long After Shocking Pool Can You Swim?

Shocking a pool is a widely common process that is done in several swimming pools. It is also done in spas, hot water springs, or any other source where there is water. The primary reason for the shocking pool is to reduce the toxic bacteria and algae in the water body.

Shock chlorination is done by adding chlorine to the water. It is performed by adding a very large amount of sodium hypochlorite or chlorine bleach to the water. It is vital to remember that after the pool water is shocked, one should not swim in it for at least 24 hours.

The shocking pool is done in a manner wherein the added chlorine is about 10 times the amount of chloramines present in the water. This entire process of enhancing the chlorine content to this level is termed as ‘shocking’.

The water after being shocked is safe to be swum in after the sodium hypochlorite content in it goes below 3 parts-per-million (ppm) or even less. This could take about 24 hours and thus it is advisable to wait an entire day after the shocking pool to swim in it again.

The time that is taken by the shocking process to get completed1 – 2 hours
The time to stay out of the pool after shocking24 hours

Why Does It Take So Long After Shocking Pool To Swim?

Chlorine levels in the water keep on fluctuating as they are never constant. Pool chlorine helps in fighting harmful bacteria and algae, thereby helping to keep water-borne diseases at bay.

Bacteria can enter the pool water through debris, sunscreen lotions applied by the swimmers swimming in the pool, bird droppings, etc. All this can lead to the buildup of nitrates and ammonia in the pool water. However, this problem can be tackled by increasing the chlorine content of the water by shocking the pool.

Shocking the pool involves adding chlorine up to a level at which all the unwanted algae, bacteria, and other contaminants are destroyed. It helps in breaking apart all the combined chlorine, popularly referred to as chloramines, thereby increasing the levels of free chlorine.

Free chlorine is safe as it interacts with all the harmful contaminants and kills them off. This helps in maintaining the pool water and keeps the water safe for swimming. On the other hand, combined chlorine is bad and not free. It does not work as an effective sanitizer by killing germs and bacterial like free chlorine does and hence, its level should always be less than the level of free chlorine in the water.

When a pool is shocked, shocking releases an increasing amount of free chlorine in the pool that helps in regulating the chlorine levels of the water. As a general rule, the free chlorine should be raised till it reaches the breakpoint i.e 10 times the content of combined chlorine.

Shocking the pool in the evening is considered ideal as by that time all the swimmers have left the pool. The pool must remain unused for swimming for at least 24 hours after the shocking process is done on the pool water.


The chlorine content of the water is required to be kept in check and hence the process of shocking the pool is undertaken to keep the pool safe and clean for swimmers. There must be a time gap of at least a day between the shocking pool and swimming as it takes about 24 hours for the pool water to have the chlorine levels under control which is not irritating to skin or eyes.

Thus, it is a good idea to shock the pool once a while like after a party or after extremely hot weather or excessive rain as these conditions might mess up the chlorine content of the water, and shocking the pool could help in such circumstances.



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Hi! I'm Nidhi.

Here at the EHL, it's all about delicious, easy recipes for casual entertaining. So come and join me at the beach, relax and enjoy the food.

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