Home » Too Much Chlorine in Pool: The Dangers & How to Lower

Too Much Chlorine in Pool: The Dangers & How to Lower

Girl swimming under water in a pool

We’ve all done it. It’s easy enough to do. You’ve put too much chlorine in your pool.  But is too much chlorine in your pool dangerous? And what are the signs? And how do you fix it?

Of course, too much chlorine in pool water can be dangerous. Exposure to over-chlorination can provoke asthma, lung irritation, and potentially skin and eye irritation.  As well as being potentially bad for you, it’s bad for your pool.

In addition to potentially dangerous health issues, high chlorine levels will also start to fade your swim wear over time.

And depending on which chlorine product you used, high chlorine levels may impact your pool’s pH level. Liquid chlorine, calcium hypochlorite (cal-hypo) and chlorine from a saltwater chlorine generator raise pH levels in a pool. Trichlor, another stabilized chlorine, will more likely lower slightly the pH whilst Dichlor, is fairly neutral in pH.

Having said that, however, there are some myths that need to be put to bed.

Chlorine Myths

You Can Smell it When there’s Too Much Chlorine
No you can’t. What you’re smelling isn’t chlorine: you’re smelling chloramines. In fact, the “chlorine” smell actually means your pool has too little chlorine. Or, at least, too little free chlorine.

Chlorine oxidises body oils, suntan/sunblock oils, cosmetics, sweat, urine, and other human bodily waste, as well as bugs, leaf mould, etc. What it does with them is to produce ammonia based compounds of chlorine called chloramines.

That’s what you’re smelling! The residual chlorine that hasn’t yet oxidised organic matter is called free chlorine – and that doesn’t smell at all.

Basically, your pool has 2 types of chlorine: free chlorine and combined chlorine. Free chlorine is “good” chlorine: it’s still available to kill germs. Combined chlorine is chlorine that’s “combined” with an oxidised organic matter. When the combined chlorine level gets much above 0.2ppm it’s time to get rid of it. And the only way to get rid of it is by shocking the water with – guess what – chlorine.

We recommend this Shock Treatment.

HTH Pool Shock Treatment (Cal-Hypo)


  • Powerful shock treatment and quickly sanitizes, kills algae & organic matter
  • Compatible with gunite, concrete, vinyl liners, saltwater systems, 
  • Each bag treats 13,500 gallons (51K litres) of pool water
We're industry experts and only recommend products we would use ourselves. If you click this link, we may earn a commision at no additional cost to you.

You can read more in our article How To Shock A Swimming Pool For Beginners (In 8 Easy Steps).

Too Much Chlorine in the Pool Stings Your Eyes
Well, yes it can. However, in 9 times out of 10, what’s stinging and causing you red eyes actually isn’t chlorine; it’s the chloramines. Or rather, it’s because the chloramines are affecting the pH balance of your pool water.

The human eye has a pH between 7.4 and 7.6. If the pH balance of the water is too far outside of this range it’s going to irritate your eyes.

Too Much Chlorine in the Pool Irritates Your Skin
As above, most of the time it’s not the chlorine that’s irritating your skin – it’s the chloramines and the pH of the water.

Skin irritation from swimming is usually caused by bacteria in the water: most commonly the bacterium Pseudomonas aeruginosa that manifests itself as a red, bumpy rash. Its other most common manifestation is as an ear infection.

To quote the American Centers for Disease Control and Prevention: “Ear infections, especially in children, and more generalised skin rashes may occur after exposure to inadequately chlorinated hot tubs or swimming pools.”

The important point is this: chlorine kills bacteria. But chlorine works most efficiently in water with a pH of 7.4-7.6. At a pH of 8.0, chlorine’s germ-killing capacity is 80% less effective.

I will point out that excessive amounts of chlorine will make your skin go red. It would have to be really high though. If you’ve ever got some bleach on your skin, then you know that if you don’t wash it off quickly, it will irritate the skin and make it go a little red.

Too Much Chlorine in the Pool Turns Blond Hair Green
No, it doesn’t. What turns blond hair green isn’t chlorine – it’s copper. To be fair, some chlorine manufacturers include copper in their product; but copper pipes or a copper heater can also introduce the element into the water. Also some algicides contain copper as does well water.

The green hair thing is caused by letting copper infused water dry naturally on your hair and then, once your hair has dried, shampooing it. Since most shampoos have a pH of 9 or more, the shampoo oxidises the copper residue in your hair and turns it – yup – green.

The way to avoid green hair is (a) to check the label on your chlorine to ensure it doesn’t contain copper, (b) to rinse your hair in freshwater after you swim, or (c) to wash your hair with a swimmer’s shampoo that has a lower pH.

We recommend this swimmer’s shampoo and conditioner.

UltraSwim Repair Shampoo & Conditioner
  • Removes chlorine & chlorine odor from hair
  • Leaves hair soft & nourished
  • Restores and repairs dry, damaged hair

How to Lower the Chlorine in Your Pool

pool strip test kit 4 way 1

To avoid too much chlorine in pool side effects, the first thing to do is to test the chlorine level.

In order to figure out the best treatment method for how to lower chlorine in pool water, you need to determine the scale of the problem. If the chlorine level is only slightly high – say, 4ppm or so – and presuming you’re not planning on using the pool for an hour or two, then the easiest answer is usually masterful inactivity.

If the chlorine level is significantly higher – say, you recently shocked the pool but forgot about the pool party you’d arranged – your pool’s going to need an intervention.

So, depending on the severity of the over-chlorination problem, and the amount of time you’ve got before you need to use the pool, here are your options.

We recommend the Water Test Strips and this Liquid Testing Kit. You can get such products here:

Leisure Time Test Strips

Leisure Time Test Strips

  • Tests for pH, alkalinity, calcium hardness, and chlorine
  • Compatible with chlorine and ozone sanitizers
  • Easy-to-read chart on the bottle
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Taylor K-2006 Test Kit

Taylor K-2006 Test Kit

  • Comprehensive water testing solution for pools and spas
  • Measures chlorine, pH, acid demand, base demand, calcium hardness, and cyanuric acid levels
  • Effective water treatment and maintenance
Check Price
Disclosure: We're industry experts and only recommend products we would use ourselves. This post contains affiliate links, so we may earn a small commission if you purchase through links on our site. There's no additional cost to you.

1.  Stop Adding Chlorine
If your chlorine reading is only a little over 3ppm don’t sweat about it. Just stop adding more chlorine to the water.

If you’ve got a saltwater chlorine generator ((sometimes called a chlorinator) or a chlorine feeder, turn it off or reduce the power level.

If you use a chlorine floater, remove it from the pool.

If you’ve got a chlorine tablet in your skimmer or in your pool, remove it.

As long as you’re not adding more chlorine to the water, by the time a couple of swimmers have jumped in and added the de-chlorinating effect of their smelly feet, armpits, and backsides to the accumulating dirt, debris, and bugs that constantly hit the pool, the problem will solve itself.

After you’ve stopped adding chlorine, you’ll want to maintain the optimal chlorine level. To do this, you need to use the right type and number of chlorine tablets for your pool.

2.  Uncover Your Pool and Let Sunlight Do the Work
If it’s a bright, sunny day and you’ve got a couple of hours to spare before you need to use the pool, just take the pool cover off. The ultraviolet in natural sunlight destroys chlorine, and the direct sunshine of a cloudless day is quite capable of depleting 90% or more of a pool’s chlorine level in just 2-3 hours.

Again, as above, don’t add chlorine to the water while you’re waiting for the natural sunlight to do its thing. Make sure you don’t have any undissolved stabilizer in the water or add any additional stabilizer as this will extend the time it takes chlorine to dissipate in the sun. 

Do monitor the water regularly, though, and resume normal chlorination when the readings drop to 2ppm.

3. Add a Chlorine Neutralising Chemical to the Pool
This is the quick fix, especially if you’ve really overdone the chlorine and you’re in a hurry.

As with most quick fixes, though, there are caveats and downsides – but we’ll come to those in a minute.

The two most common chlorine reducing chemicals are Sodium Thiosulfate and Sodium Sulfite. Alternatives include Sodium Bisulfite and Sodium Metasulfite. These chemicals are usually come in large bags and are a lot cheaper than commercially packaged “chlorine neutralisers” sold in bottles.

If you would like to use a Neutraliser, we recommend this one here.

In The Swim Chlorine Neutralizer
  • Quickly and effectively lowers chlorine levels
  • No premixing required
  • Use when chlorine levels are too high

Hydrogen Peroxide also works – although not the domestic hydrogen peroxide sold in first aid kits.

Whatever you use, follow the directions carefully. With the filter running, pour out a measured dose into the pool skimmers. Typically, 60 grams will reduce the chlorine by 1ppm in an average backyard pool of 32 m2, or approximately 41,000 litres of water).

Make sure you add the neutraliser gradually. And don’t add too much at once or else you’re liable to destroy all the chlorine.

If you artificially neutralise the chlorine it’s incredibly difficult to get it back up again. So only add around half of what you think you need, and then test the water before adding more.

All these chemicals can dramatically reduce the pH of the water. So make sure you test the pH before and after adding the chemicals and adjust accordingly. You can read more on how to raise the pH level here.

Also, if you artificially reduce the chlorine, the level of stabiliser (cyanuric acid) will remain the same as it was before. The net effect is that, if you later add chlorine via a tricholor tablet, the stabiliser level of your pool is going to rise. The stabiliser level needs to be maintained at 30-60 parts per million (ppm).

Below that, chlorine rapidly degrades, and at anything above 100ppm, the stabiliser actually prevents the chlorine from sanitising the water.

4.  Replace Some of the Existing Pool Water
While this is a natural process of dilution, it’s not the quickest or cheapest option.

If you have a sand or DE filter, the quickest way to get rid of over-chlorinated pool water is to backwash. Of course, refilling the pool with fresh water to dilute the existing chlorine takes a bit longer.

And it costs money in terms of water bills. Plus, the addition of fresh water is going to throw your pH, alkalinity, stabilizer, and calcium hardness seriously out of whack: so make sure you test and adjust once you’ve finished topping up the pool.

We have a full article on neutralizing chlorine here: How to Neutralize Chlorine in a Pool

Swimmers Shampoo and Conditioner

Pool Water Testing Strips or Liquid Water Testing Kit

Shock Treatment

Swimming Pool Cover and Pool Cover Roller

Chlorine Neutraliser

pH Up

Pool Water Stabiliser

Related Reading: 5 Alternatives To Using Chlorine For Pools

22 thoughts on “Too Much Chlorine in Pool: The Dangers & How to Lower”

  1. This article is contradicting and confusing. The first part states. “Of course, too much chlorine in pool water can be dangerous.” Then the second half states. The myths
    “Too Much Chlorine in the Pool Irritates Your Skin”
    As above, most of the time it’s not the chlorine that’s irritating your skin – it’s the chloramine and the pH of the water. So is too much chlorine dangerous yes or no? One part said yes too much will burn you and the second part said no the opposite is true too little chlorine will cause bacteria to grow which is what actually irritates your skin not the chlorine. Can we get some clarification.

    • Too much chlorine and not enough chlorine could cause skin irritations. If your skin comes in contact with household bleach (chlorine), and it’s not washed off quickly, it will make your skin red and irritated. Too little chlorine could also lead to bacterial growth and irritated skin. Additionally, high or low pH will irritate the skin.

  2. also, Chlorine does not lower ph. It gives a false reading by bleaching the reagents. If you are suffering from low ph symptoms, it is because your ph was too low to start with, not that your chlorine lowered the ph.

  3. In your second paragraph you say that high chlorine lowers your PH and makes the pool acidic. Chlorine is the polar opposite of acidic with a high PH, resulting in PH increasing. That is why you add muriatic acid to chlorine sanitized pools, to lower the PH creep caused by the introduction of the basic (opposite of acidic) properties of chlorine. From memory sodium hypochlorite (liquid chlorine) has a PH of 13.0, while the acid we add (muriatic/hydrochloric) has a PH of 1.0.

    • Yes you’re right. We’ve fixed this typo.

      It depends which way of adding chlorine you use as to whether you’ll have increasing pH levels. As you said, liquid chlorine has a high pH whereas other chlorines such as Dichlor have neutral pH. Saltwater generators are well known for increasing the pH in pools.

  4. You never really said why High chlorine is bad. Chlorine in solution has little effect on humans. All your comments were about Chloramines. High Free Chlorine with little or no combined chlorine should be very efficient. PH is the thing to watch. I would love it if someone could point to real evidence that high chlorine is an issue

  5. We had our pool painted with epoxy paint in the spring. Someone left the chlorinator on too long which raised the chlorine to an extremely high level, twice. Although the levels are ok now, our feet, hands, knees, and bathing suits are ‘white’ when they come in contact with the pool’s paint. Can this be from the chlorine degrading the paint? If so, how do we treat it ?

  6. This is probably the most obvious answer of all, but also the most controversial:

    Why do so many people feel the need to drain lakes and rivers in some countries but not others? Racially Integrated public pools and rivers and lakes polluted by industry.

    Solution: 1> stop being racist. 2> stop polluting the water. That means living without products that produce pollution. 3> admit your faults.

  7. Ok, so I was in Oklahoma last fall when the Rosenberg stealers were in town. I hadn’t had much sleep and I wanted to get some rest. I got in my hot tub to get a bit of shut eye before my big fight with audley Harrison at dusk. I drifted off and woke with one hell of a problem the chlorine in my tub had eroded my entire body. It was not enjoyable.

  8. In my experience, if the water isn’t crytal clear (dancing diamonds in the sun and the ability to see the drain on the bottom), you’ve got a chemical imbalance that needs to be taken care of.
    Slightly cloudy is the first baby step to an algae attack which can be very expensive to fix

  9. My brothers roommate once asked how much chlorine is enough because he came in to the flat and wanted to show everyone where exactly the spa had burned his private areas. It turns out the answer was exactly purple because aliens don’t wear hats. Just sayyin’

  10. I think it is important to note that the appropriate free chlorine level should be based on the level of cyanuric acid. If the cyanuric acid level is 80, for example, 4 ppm free chlorine is not too high. In fact, it is too low for the chlorine to be an effective sanitizer.

    • Ugh, been there, done that, got the t-shirt. My pool is now full of children’s tears. Boy was that a mess to clean up.


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