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Home » Water Education & Testing » How to Remove Tannins in Water

How to Remove Tannins in Water

By: David Trinh
Last Updated:
how to remove tannins in water

If you’re not used to getting your water supplied from a well, then tannins aren’t something that you’ve had to worry about in the past.

When you move to an area where the water supply is different from the city, you may encounter impurities from well water you never had to deal with before. One of which is tannins, also known as humic acid.

This article will review what tannins are and how you can effectively remove them from your water supply.

What Are Tannins?

Before we jump into how to remove tannins from water, it’s helpful to know what they are.

Tannins are fermented organic materials that are created by the breakdown of vegetation.

You may be familiar with tannins if you drink wine or are familiar with the wine making process.

Instead of tannins created from grape seeds, skin, and stems, the stuff in your water is created from decomposing vegetation and peaty soil that collects as water passes through the aquifer that supplies the well at your home.

There are more than 8,000 types of tannins that fall into two categories: condensed and hydrolyzable.

The simple difference between the two is that condensed tannins are not hydrolyzable to other molecules.

Are Tannins Harmful?


Tannins are not harmful to ingest, so they aren’t something that the EPA tests for or issues warnings about when they’re present in drinking water.

While the tannins themselves may not be a health concern, if you think you have them in your water, you’ll want to get your water tested since the presence of tannins may be a sign of other contaminants, including bacteria.

Instead of being a concern, tannins are more of an aesthetic issue. Tannins give your water an unappealing appearance and a musky odor, which is why most people want them out of their drinking water.

How Do Tannins Get in Your Drinking Water?

As mentioned earlier, if your water isn’t coming from a water treatment facility, the water is coming into your home through your well water system.

With a well water system, tannins can seep into the water through cracks in the well walls.

Water that flows through rivers and lakes is in near-constant contact with dead leaves and other decaying matter. When the water runs over them, it gives it a brownish color thanks to the tannins that rub off.

Similarly, well water can come in contact with the same decaying matter, mainly as it flows into the aquifer.

Get your water tested and well inspected regularly to ensure your water remains tannin-free. 

Effects of Tannins in Your Home


While tannins aren’t harmful to consume, they aren’t pleasant to the senses. They have a musky, dirty odor, tangy aftertaste, and a brown, dirty appearance.

You wouldn’t want to wash your hands or take a shower in what looks like contaminated water.

The discoloration can also stain your clothes when you do laundry—most noticeably your whites.

But your laundry isn’t the only thing that suffers from tannins in the water. 


Untreated water will stain your dishes, porcelain fixtures like your tub, toilet, and bathroom sink, too. You’ll probably want to wait on using any heirloom china you have until after you treat your water and remove the tannins.

Murky Drinking Water

If you have young children or teenagers that you’re trying to encourage to drink more water, your battle may be more difficult with tannin-contaminated water.

It has three strikes against it: it smells bad, has an aftertaste, and looks like dirty water. Filtering the tannins from your drinking water will make it more presentable to all families and guests. 

Can Create Disinfection Byproducts

Even though tannins on their own aren’t harmful to consume or use, they can react with chlorine and form new compounds, referred to as disinfection byproducts. These are similar to trichloromethane, a suspected carcinogen.

Can Interfere with Filters

Tannins can interfere with water treatment equipment that filters other contaminants. The resins in iron filters, neutralizing filters, and cation exchange filters can become covered with tannins and stop functioning correctly.

If you don’t want to deal with repair costs in the future, you’ll want to remove the tannins from your water as soon as possible.

How to Test for Tannins in Well Water


The Environmental Protection Agency (EPA) suggests that you get your water tested by your local state’s private drinking water well program. Your local or state health, or environmental agencies can run tests for tannins and other contaminants.

Before spending any money, you can also do a simple test that doesn’t require any equipment. All you need is a full glass of water in a clear cup. Pour some of your home water into the cup and look at it after leaving it overnight.

If the color has settled to the bottom of the glass, then you know your issue isn’t tannins. Instead, the problem is the presence of iron and/or manganese. If the color remains the same as when you filled the glass, the chances are high that you have tannins in your water.

Now that you know you have tannins, it’s essential to determine how much of the contaminant is in your water. There are numerous laboratories with the ability to test tannin concentration in drinking water when you send them a sample.

You can purchase a water test kit from a DIY supplier, or hire a water treatment company to test your water and make recommendations based on the results.

If you plan to send a water sample for tannin testing, you should consider having the laboratory test for additional contaminants.

When you have tannins in your water, there’s a high probability that hardness-causing minerals are present. Consider also testing for iron, as the presence of iron can create a false-positive in your at-home tannin test.

How to Remove Tannins from Water

Now that you’ve tested your water for tannins and the tests confirm that they are present, how do you remove them?

Here are some of the different ways you can remove tannins from your water, how effective each process is, and their best purposes.

Ion Exchange


It’s common to use a water softener system to remove hardness using salt. However, you can use the same processes to remove other contaminants, including tannins. Since water softening systems use a cation/ion exchange absorption process you could use it to remove tannins from your home’s water.

Water softening systems with ion exchange media include large tanks with enough room to accommodate the necessary reactions. Typically, you would use positively charged media, like styrene-based chloride or an acrylic resin to initiate the ion exchange with the negatively charged tannins.

As the ions exchange, the anion resin regenerates salt, keeping the resin bed clean. The water treatment resins usually regenerate every two days to avoid foul smells. Once regeneration completes, the ion exchange process restarts.

While this process can help reduce sulfate levels along with the tannins, it has some drawbacks. Your system will produce more water waste, require frequent resin replacement, and it can impact the pH levels in your water.

Additionally, the anion exchange resins used will cost several hundred dollars in salt each year. This process is not environmentally friendly, either. You can waste up to 80 gallons of regenerating water by using ion exchange. On top of that, the resin used to remove tannins needs replacement every five to six years.

Reverse Osmosis

Reverse osmosis filtration

Reverse osmosis can be a costly option, but it’s highly efficient. Reverse osmosis (RO) systems can treat and filter out even the tiniest impurities in your water, including tannins.

The RO membrane consists of small pores that can trap particles over .001 microns in size. You’ll remove tannins, bacteria, fluorides, and various chemicals with this treatment system.

Also, RO systems use several different water filters, like carbon, and pre-sediment filters to ensure that more than 99.9% of matter is removed from the water.

With this very effective filtration capability, you get some of the purest water available using reverse osmosis filtration. RO systems cost more than other whole-home water treatment systems, but the multi-stage systems allow you to access clean water immediately.


Another way that you can break down the tannins in your water is by using oxidizing agents like chlorine. The oxidizing agent attracts the tannins and causes them to settle in larger particles that can’t pass through your system.

You can determine how much chlorine you need and how long to expose water to the chemical with a jar test. This will help you select an oxidation method and a detention time.

To perform a jar test, fill a jar with water, mix it with a chemical oxidant, and let it stand. From here, you can record the amount of time it takes the water to turn a rusty color and the amount and type of oxidant used.

Without moving the jar in the process, time how long it takes for the rusty color to settle at the bottom of the jar. You’ll have to repeat this process with different oxidation agents to find the best one for your system.

Additionally, you probably won’t want the excess chlorine hanging around in your water. You can install an activated carbon filter at the end of your tank to remove any residual chlorine from your water.

When you’re testing with chlorine, remember to be careful and closely monitor the process. It can mix with the tannin compounds in your water and produce trihalomethanes (THMs), which is a known carcinogen and may potentially cause reproductive issues in women.

Frequently Asked Questions

Will carbon filters remove tannins?

Activated carbon filters will remove some of the tannins from your water and improve the overall quality. The amount of tannins extracted by carbon filters is limited because they can absorb tannins with significant molecular weight. However, activated carbon filters aren’t nearly as effective as the alternatives and have a limited lifespan. 

How can I avoid getting tannins in my water?

Since tannins occur naturally in many water sources it’s easier to remove them before drinking rather than taking steps to prevent them. However, there are a few ways to protect your well from tannins:

  • Slope the area around the well to direct runoff away from it.
  • Build wells deeper because shallow water sources tend to have more tannins.
  • Install a cover and seal any cracks or holes to keep debris out.
  • Keep track of maintenance records to ensure you keep an eye on the tannin levels.
  • Implement inspections and pumping of septic systems as part of your annual maintenance.

What is the best method for tannin removal?

Though you have a few options for removing tannins from your drinking water, reverse osmosis systems remain the best choice. If you can afford to invest in a RO system, you get the purest drinking water possible from every faucet in your house.

If you can’t swing an RO system, you can install a water softening system with ion exchange resin or an oxidizing filtration system to clear up your drinking water quickly. Make sure you choose a positively charged resin or media to draw out the tannins and keep an eye on the levels in your tank.

I have a new well—is it essential to test for tannins?

Testing your new well for tannins is an excellent way to have a baseline for the water in your well. If there aren’t any tannins at the start, you’ll know you have a problem when you test your water regularly. You don’t want to wait until you begin to smell the water or see changes in your laundry before you start removing tannins from your water. Plus, testing for tannins could identify other problems with your water that could impact your water flow or make it unsafe to drink.


The good news is that the tannins in your water aren’t harmful. The bad news is that, if left untreated, you’re stuck with smelly, bitter-tasting water that can stain your clothes and your fixtures. Either way, if you have tannins it may be best to look for an adequate water filter for your home.

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David Trinh
David is an expert in all things plumbing, heating, cooling, and water treatment. He got his start in the plumbing business working on fixing all types of home improvement issues including water leaks, broken toilets, appliance installation, and more. Over time, he learned a ton about installing and choosing the correct water treatment products for homeowners.

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