If you’ve seen the Statue of Liberty, its green color came from the oxidation of copper due to exposure to air and water. A similar chemical reaction can occur in pools when there’s copper.
The copper-infused water can turn a greenish hue that is commonly confused for algae. While we generally avoid swimming in algae, you may wonder if you can swim in a pool with high copper levels.
High levels of copper in the pool are unlikely to pose any imminent health concerns since your skin doesn’t technically absorb the copper. However, it has the potential to leave a green stain on not only the pool surfaces, but also on swimmer’s hair or bathing suits!
However, if you have some unruly swimmers that are actually swallowing pool water that has high levels of copper, they could experience an increased risk of stomach issues.
We’ll take a deep dive into this topic and will explore how to remove copper from pool water.
Swimming in Pools With High Copper Levels
When copper reacts with oxygen or chlorine in the water, the oxidation process starts. As a result, copper carbonate forms and exhibits a greenish tint. So, instead of a sparkling blue pool, you may be left with an emerald green pool.
You should aim to limit the amount of copper in your pool to around 0.2 parts per million (ppm) as this is generally considered safe for swimming. If the copper level rises above 0.5 ppm, you could start to see some adverse effects.
High copper levels can eventually lead to staining of pool surfaces. The nice bright blue pool walls could start showing a dingy brown hue as the green copper starts to accumulate. Over time, the green could actually turn to a black stain.
Aside from that, you may notice your swimsuit or hair turn a shade of green if you’re swimming in a pool with high levels of copper. This is more typical for blonde hair and lighter colored swimwear.
Although your skin can’t absorb copper, accidentally swallowing water in pools with extremely high copper levels can cause harmful effects on your body.
Ingesting the contaminated water can cause diarrhea, nausea, and stomach cramps. In severe cases, a person may even suffer from liver damage and kidney disease.
But, not all is bad with having copper in the pool. Sometimes, a low concentration of copper is desired to help prevent algae growth. The key is that its concentration must be controlled in order to avoid the negative effects of it.
Where Does Copper in Pools Come From?
Copper doesn’t just magically appear in pool water, but can be introduced through various sources. Here are some common reasons why there’s copper in your pool.
Most natural water sources have some level of copper. It’s a mineral you can find in rocks and soil, which gets usually absorbed by water.
Before the water reaches your faucet, it typically gets treated. However, local municipalities only filter water until it meets the minimum standards.
In the U.S., the maximum allowable level of copper for drinking water is 1.3 ppm. It doesn’t mean that this copper level is safe for your pool, though.
Copper pipes also contribute to the increased levels of the mineral in pools. When water travels through the pipes, it can absorb some of the metal.
So, when you regularly add water to your pool, you can expect the copper concentration to increase. This buildup depends on how much copper is in your local water.
Many pool owners maintain their pools by using an algaecide. Many algaecides contain copper sulfate or copper chelates as the active ingredient, which disrupt algae formation in your pool.
Since many algaecides contain copper, they contribute to the copper level in your pool. This means you’ll have to test your pool water more often for copper if you use this chemical.
As an example, one quart of copper-based algaecide that has a 7.8% concentration of copper, could raise the concentration by 0.054 ppm for a 10,000 gallon pool. While this doesn’t sound like much, a few quarts of this could raise your copper concentration above the recommended 0.2 ppm maximum.
If you are looking to ward off algae without raising copper levels, you could consider non-copper algaecides. These often use quaternary ammonium compounds, to kill and prevent the growth of algae in the pool.
When the water in your pool has a low pH, it’s acidic. Combined with the existing copper levels in your pool, the water turns green as a result of the chemical reaction.
Additionally, when water with low pH flows through copper pipes, the chances of corrosion increase. This contaminated water can reach your pool and tarnish the quality of your water.
When you have copper heat exchangers in your pool heaters, acidic water can also cause them to corrode. The dissolved copper from this set-up can cascade to your pool water.
Some chlorine sanitizers or shock treatments contain copper as an additional benefit for algae control. If you’re using a product that indicates “Plus” on the label, this may be a clue of copper addition.
Check the product labels carefully to see if they should list copper as one of the active ingredients. While you don’t need to completely avoid these types of products, it’s good to know that they could be a source of copper to the pool water.
Copper ionizers work by generating a small electric current that runs through the copper electrodes, causing copper ions to be released into the pool water. The presence of the copper helps keep the water sanitized from algae and other microorganisms.
Ionizers are considered an alternative to traditional pool chlorination methods, and are often used in conjunction with lower levels of chlorine or other sanitizers.
However, when used excessively or improperly, they pose risk of elevating the concentration of copper into the pool
How to Check a Pool For Copper Levels
It’s important to check for copper levels in your pool if you want to maintain it. Here are some ways to do it.
Method 1: Using a Test Kit
While copper test kits may vary, they usually come with a tube and reagents. Once you have the kit, all you’ll need is a water sample from your pool.
First, collect water by filling the tube to their specified volume. Then, add the reagent(s) as indicated by the kit instructions.
You can then compare the color of the water to the color chart to determine the level of copper concentration.
Method 2: Using Test Strips
If you’re looking for an easy and semi-accurate method for testing chemicals in your pool water, you can opt for test strips.
The first thing you’ll need to do is make sure your hands are clean and dry. This prevents the test strips from getting contaminated by external moisture.
Then, simply follow the instructions written on the package.
Typically, you’ll have to dip the test strip deep into the pool water. The recommended depth is about elbow-deep.
It’s also necessary to conduct the test in a well-circulated area of the pool. This way, you’ll get a representative sample of water.
Gently sway the strip underwater for about five seconds, or however long the package instructs.
Once the strip is out of the water, lay it flat on a surface away from the sun. Wait for the strip to change shades and compare it to the color chart.
Method 3: Consulting a Pool Store
If you don’t have access to copper test kits, the next best option is to bring a water sample to your local pool store. Simply, take a bottle of water from the pool and hand it over.
The store should be able to test the water and provide you with the amount of copper in the water.
Method 4: Visual Clues
If you’re unable to measure the copper level in the pool, you can also look for visual clues in the pool.
Green, brown, or black stains that don’t brush off could be a sign that copper or another metal is binding to the surfaces.
Another common indicator of high copper levels is the water turning green shortly after shocking the pool with chlorine. The shock will oxidize copper that is suspended in the water causing it to turn green. If your water turns green immediately after shocking, it’s likely to be due to copper rather than algae.
How to Remove Copper From Pool Water
Unfortunately, removing copper from the pool water isn’t always a quick and cheap process. In some cases, it’s easiest to allow the copper to remain in the water, but in a state of solution that will eliminate its problematic effects.
Here are three primary ways to remove copper from pool water.
One way to reduce the effects of copper in pool water is to use a sequestering or chelating agent. These will bind to copper ions which will prevent them from reacting with other chemicals, and will stop them from oxidizing (i.e., staining).
Sequestering agents have polyphosphates that hold copper in suspension. On the other hand, chelating agents are made from ethylenediaminetetraacetic acid (EDTA), which can also lower the chlorine levels of your pool.
When the water accumulates high levels of copper, you may notice that it’s green and hazy. The chelating and sequestering agents help bring the clarity of water back.
It’s important to note, that these products typically don’t actually remove the copper from the pool, but simply bind to them to prevent them from reacting. Periodic maintenance dosages of the products are required after initial treatment in order to keep the copper from coming out of solution and staining.
Before adding this product to your pool, it’s recommended to ensure you have properly balanced water. You should also measure your copper levels before adding them as this will give you an idea of how much product needs to be added.
Read the instructions on the packaging to get an idea of how to use them. Keep in mind that you’ll have to do this process regularly to keep the copper levels at bay.
After 24 hours, you’re ready to test the water again. If high levels persist, you may need to apply a second dosage.
Drain and Refill
If you’d rather not have to apply periodic doses of sequestering agents to eliminate the effects of copper, you can consider draining and refilling the pool. This method allows you to dump the existing water that contains high levels of copper and replace it with fresh water.
It’s important to know that completely emptying the pool could pose risk of costly damage, particularly for vinyl-lined pools. You’ll also want to ensure that it’s not too hot outside during this.
To avoid risk of this damage, an alternative method would be to perform partial draining and refilling in order to dilute the copper concentration in the water. After draining half the water and then refilling with fresh water, you can check the copper concentration to see if it’s back to acceptable levels –the dilution process can be repeated as necessary.
Before refilling, you should test the fresh water to ensure it doesn’t contain too much copper, otherwise, you might not be any better off than when you started. If the water from your spigot has too much copper, you can consider having a tanker truck deliver pretreated water.
If considering this method, you’ll want to factor in the cost of the water along with the chemicals to re-balance. It could take days to refill a large pool using a typical garden hose, so this may be something to plan at the start or end of the pool season rather than in the middle of summer.
Reverse Osmosis (RO)
Using a reverse osmosis (RO) filter will remove copper from pool water. Unfortunately, these are not as prominent as standard pool filters and are much more costly.
If you’d rather not purchase an RO system, you may have an option to rent one. This would allow you to clear the metals currently in your water.
So, can you swim in a pool with high copper levels?
Unless you want to stain your favorite swimsuit or hair, then it’s not a great idea to swim in pools with copper. But high levels of copper in pool water are unlikely to cause any significant health concerns unless swimmers are actually drinking the water (this should be avoided even if there’s not copper in the water!).
Fortunately, you can be proactive by eliminating sources of copper into the water and routinely testing the copper level. If you have high copper levels in the pool water, there are ways to remove it and reduce its effects.
If all else fails, you can consult with a pool professional to help ward off high copper levels.
Husband and father of three (actually, four if you include the pool). I’m an avid DIY-er and weekend warrior that enjoys taking up new projects around the house to help us maximize leisure right at home. I enjoy researching and sharing various tips, tricks and knowledge to help others make their home an oasis.