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Is too much chlorine in the pool bad? After all, it is used for disinfection and thus has some properties that should be known before use.

Overdosing on chlorine carries the potential of serious adverse health consequences, and the causes of too much chlorine can vary in nature. The following sections include information on how to remedy this condition.

Causes of too much chlorine in the pool

It is strongly recommended to follow the manufacturer’s instructions when dosing the chlorine. Normally, they recommend a dosage of about 1 to 3 milligrams of the chemical per liter of pool water to ensure an adequate disinfecting effect.

Despite careful monitoring, it is always possible that there is too much chlorine in the water. In order to correct this, or to prevent a recurring problem, the reasons for the phenomenon must be found.

Often, when chlorine is added manually, an overdose occurs because, for example, there is an error in calculating the amount or the value of chlorination is not measured correctly.

If, on the other hand, you use an automatic form, for example a dosing system or similar, there may be a malfunction in the control or measurement technology. Also a not optimally adjusted pH-value possibly forms the basis for too high amounts of chlorine in the water of your pool.

Too much chlorine in the pool: The consequences

The above-mentioned reasons for an over dosage can partly already arise if the target value of the chlorine is not regularly controlled or, if necessary, corrected. This is subject to fluctuations when the pool is used more intensively, for example.

Apart from numerous interactions of the chemical pool care products with each other, which can cause unpleasant reactions, an excessively high chlorine dose in itself poses a number of risks.

Since even an ideally adjusted pH is beneficial for the pool and the pool water it contains, but not at all for human skin, whose value is normally 5.5 and not 7.0 to 7.4, an overdose of chlorine puts additional stress on it.

As a result of dehydration, unpleasant itchy spots can appear on the skin. Furthermore, both the nose and the eyes, in principle all mucous membranes, react with irritation, which is noticeable for example by redness.

3 solutions for too much chlorine in the pool

In order to prevent health problems and potential permanent consequences, it is necessary to bring the chlorine level in your pool back to an ideal level. This is done either by lowering it or neutralizing it. The following sections explain the possible solutions for fixing too much chlorine in your pool’s water.

Solution 1: Lower the chlorine level in the pool

In principle, you should prevent chlorine from continuing to enter the water, which is why you should refrain from adding it manually or turn off any automatic dosing systems that may be defective. Although the use of the pool can contribute to the decomposition of excess chlorine, however, at levels above 4 milligrams per liter of water, it is strongly advised against for health reasons.

In most cases, the decomposition of chlorine mainly takes time, and this process is accelerated with the help of UV radiation. Therefore, it is recommended to remove the cover from the pool, so that the sun can shine directly on the pool water.

In addition, you should add at least a certain amount of fresh water to the pool to reduce the elevated level, but a complete replacement is very labor-intensive as well as time-consuming, so it should be considered only as a last resort.

Solution 2: Neutralize the chlorine level in the pool

The first solution refers exclusively to the occurrence of a low or moderately increased chlorine content. In the case of high or even very high levels of the chemical, conventional measures will no longer work efficiently, which is why reduction by means of additional chemical preparations makes perfect sense. These are offered in various compositions and forms, for example, as powders or tablets.

For example, sodium thiosulfate is popular as a neutralizing chemical, and the procedure for adding it is similar in most cases. In addition to determining the amount of water, the actual and target levels of chlorine, it is also necessary to determine the required level of sodium thiosulfate before adding it to the pool water according to the manufacturer’s specifications.

In order to avoid too high an addition of chemical preparations, you should prefer a proportional use and then readjust with chlorine or chlorine sinks if the value is not yet optimal.

Solution 3: Neutralize chlorine with hydrogen peroxide

Unlike sodium thiosulfate, hydrogen peroxide is not only available in specialized stores, but also in drugstores or pharmacies.

Although this chemical has a neutralizing effect against chlorine in the pool water without any further additives or binders and is also extremely inexpensive, its use by laypersons is strongly discouraged because the risk of harmful consequences for health is not insignificant.

Hydrogen peroxide can be purchased in various concentrations, which makes dosing more difficult than with ready-made products from specialized stores. In case you dose it too high, it can be highly corrosive, possibly causing irreparable damage to the eyes, the respiratory tract, and the skin.

An overdose of chlorine can be neutralized with the help of hydrogen peroxide, but laymen or inexperienced pool owners should first replace the water to solve the problem in another way.

FAQ: Frequently asked questions about chlorine in the pool answered

What are the symptoms of too much chlorine in the pool?

An overdose of chlorine is not indicated by the typical chemical smell that many people associate with it, as is often assumed. This usually indicates too much combined chlorine, known as chloramines, in the pool water and requires other steps such as shock chlorination.
Too much free chlorine, which can develop its disinfecting effect, is noticeable in the short term by irritation of the mucous membranes, for example the eyes and nose. Classically, reddened eye areas occur, but also the skin usually suffers from too much chlorine, which leads to dry and itchy areas.

Can I still swim in the pool if there is too much chlorine?

There are no exact limits in this regard. However, one should generally be careful with too much chlorine in the pool in order not to run any health risks.
Due to the fact that chlorine reacts with components of the human body, for example urine, and thus hazardous substances can be produced that have the potential to alter genetic material or cause cancer, increased caution is advisable. In public swimming pools, up to 10 milligrams of chlorine per liter may be used in a short period of time if the pool is heavily contaminated.

Are there alternatives to chlorine in the pool?

There are some possible options you can switch to if you don’t want to use chlorine. These include, for example, the three popular alternatives of bromine, Baquacil, and active oxygen, the latter of which should come from a specialty store as it is a hydrogen peroxide product.
Of course, just like the use of chlorine, these options also have advantages and disadvantages. To be able to use a small amount of chlorine, you should pay attention to hygiene measures, such as showering before swimming, and covering the pool during long periods of non-use.


Chlorine overdose can cause short-term health consequences in humans, such as irritation of the mucous membranes of the eyes and nose or dehydration of the skin. Furthermore, a reaction of chlorine with human skin scales, urine or even hair leads to the formation of dangerous substances, which in the long term can influence the genetic make-up or promote cancer.

In cases where the chlorine content is only slightly or moderately elevated, measures such as the passage of a certain period of time in combination with direct exposure to sunlight are already potentially sufficient to remedy the problem.

Higher amounts can be neutralized with a chemical preparation such as sodium thiosulfate, although care should be taken and unnecessary overdosing of the chemical avoided.

If these steps do not lead to a satisfactory result, the pool water can be replaced so that you can enjoy refreshment in the cool water again in the near future.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.