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Bath Water Filters
By Dr. Meg Christensen | Updated December 2025
Do bath filters really work? I've tested the claims and rated four options—from most to least effective. One proven hack that actually works, two methods with limited evidence, and one alternative approach for when filtration isn't enough. Scroll down to learn how bath water filtration actually works, what contaminants can and can't be removed, and why most bath filter marketing is misleading.
The best bath filter is a shower filter attached to your tub faucet. Shower filters are much better at removing contaminants than bath filters. They’re bigger, so they have more filtration media than a bath tub filter. They deal with slower flow than a bath faucet, so can capture more toxins, too. And, several brands have testing showing that they’re actually effective for thousands of gallons— the Weddell Duo, above, is even verified to remove chlorine, PFAS, and microplastics. There are 2 hacks to make your shower filter work as a bath filter: 1- Attach a shower filter to the bath faucet diverter, as above. Here is a faucet it will work for, if you don’t have the right type currently. This slows the flow slightly, but will still fill your tub, and you won’t lose heat. 2- Use a hose dangled from your showerhead into your tub. The water may cool slightly as it makes its way down, so start with hotter water. See all the shower filters I recommend here. All have a universal fit, so will work on any hose or diverter.
Finally, a bath filter that isn’t a ball! Bath filters are probably less effective than shower filters at removing contaminants because of the high rate of flow through them (read more below), but this one does force water through it, and has legit filtration media, so very likely does remove chlorine. I’m glad to see that the Canopy uses KDF, activated carbon, and calcium sulfite in their filter, and they don’t overstate claims about what it can remove, which I appreciate. I would personally skip adding their scent — yes, they’re made with pure essential oils, but also synthetic ones. You can read more here on my scents page. Overall, the Canopy is probably the best bath water filter on the market so far. Dishwasher safe, which is nice.
If bath filters can remove anything, it’s chlorine. But guess what else works to remove chlorine? A pinch of vitamin C (ascorbic acid) powder. You can see the very exciting chemical reaction written out here. Adding a tablespoon to your bath water instantly neutralizes the chlorine, is safe, and inexpensive. It won’t remove any of the other contaminants in your water supply, but neither do most filters. And, reducing chlorine can mean less skin irritation and less lung irritation from breathing vaporized chlorine in. FYI, I’m skeptical that bentonite clay removes toxins from bath water like some suggest— while it does bind to toxins in the digestive tract, they’re flushed out of your body, and that’s how it’s effective. In this case, they linger in the tub, so I can’t verify they would truly do anything. It can also cause problems clogging your tub drain. Vitamin C causes a true change in chemistry.
These filters don’t exist yet, and are still in the funding phase, but it appears that they are made of slightly more filtration media than most bath balls, and its design ensures that all the water is forced to go through it, not spill over the sides. They are planning to use KDF, which is an NSF certified copper-zinc mixture that is the gold standard for removing chlorine. I’d love to see testing on this once its released to see if it can truly remove chlorine effectively and at what percentage, with hot, high pressure water rushing through it! You can contribute to their kickstarter through this link or sign up to get updates from them. An elegant design.
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More About Bath Water Filters
Do bath ball filters work? Does the Tubo bath filter really work?
It is highly unlikely that any brand of bath ball meaningfully removes water contaminants. There are two reasons why:
Most models are designed so that bath water will splash over the sides.
Bath filters are small, so don’t have enough filtration media to capture contaminants, and they are poor at removing contaminants from hot water. Whole-house and under-sink water filters work most effectively on cold or room temperature water, at a slow flow rate, and they’re built with a lot of filtration media. They remove a lot, but still not everything! Shower filters capture even less, because they’re dealing with hot water and a much higher pressure (read more here). The water coming through the bath spout is twice as fast as a shower, and these ball filters are even smaller than shower filters, so there’s less filtration media for contaminants to get stuck on.
So, while a bath filter may capture a tiny bit, they may be a waste of your money. Until I see testing with convincing results, I remain wary.
The new designs like the Canopy and Bath Haus (above) are better, since they force the water to go through real filtration media. If you change the filter frequently, it may be effective. I would still recommend vitamin C or a shower filter with a hose for the best removal (or whole house filtration!) That said, I know those methods can be inconvenient, and some filtration is better than none, so choose what works best for you.
Why are there so many misleading tub filter claims?
There is SO much healthwashing in the water filter business! My best guess as to why is three-fold:
Water contaminants are invisible, and often don’t have a detectable smell or have a color, so it’s very easy to claim more purification is happening when it’s really not. Self-testing your water is the best way to know if a filter is working, but it can be really expensive —running you hundreds of dollars to assess both before-and-after samples for heavy metals, PFAS, and other issues. Therefore, a company can get away with exaggerated claims. This is the most sinister of my guesses; that there is some level of deception happening for the purpose of making money.
Some brands may take legit, general facts about filtration media and retroactively (but inaccurately) apply them to their product specifically. Similar to the Arsenic example above, a good amount of KDF can remove heavy metals from water— there’s research on this. But if you put a teaspoon of KDF into a tub filter and run hot water on high pressure through it, it may not remove any! It’s context-dependent. So, I think some claims are made about the media filtration generally, but aren’t actually tested or verified for the filter itself.
Competition! If your filter’s “contaminants removed” list is shorter than your competition’s, it might look less effective to the untrained eye. If one brand is claiming it can remove a long list, then it perpetuates the spread of unverified long lists across brands.
What is KDF?
KDF stands for Kinetic Degradation Fluxion— it is just a combination of copper and zinc. It is the gold standard for removing chlorine.
Do bath filters remove chlorine effectively?
Bath filters with KDF (copper-zinc), activated carbon, or calcium sulfite can remove some chlorine, but their effectiveness is limited by hot water temperature, high flow rate, and small filter size. Bath water flows roughly twice as fast as shower water, giving contaminants less contact time with filtration media. The most reliable way to remove chlorine from bath water is using a shower filter attached to your tub faucet (which has more filtration media and third-party testing) or adding a tablespoon of vitamin C powder directly to your bath water, which instantly neutralizes chlorine through a chemical reaction.
Do you absorb chlorine through the skin?
No. However, chlorine can affect your health in two ways: coming into direct contact with your skin, and being inhaled into your lungs as a vapor from hot bath water steam. With direct contact, chlorine can cause itchy skin and dry hair. Inhaling it is associated with lung and throat irritation, typically at the higher doses found in swimming pools, but sensitive individuals may notice it in a bath, depending on your water supply. Your skin does not absorb chlorine into the body very well, so this is less concerning.
Does vitamin C really remove chlorine from bath water?
Yes, vitamin C (ascorbic acid) instantly neutralizes chlorine through a chemical reaction. Adding about one tablespoon of vitamin C powder to a standard bathtub neutralizes chlorine on contact. This method is inexpensive, scientifically validated, and doesn't require any equipment. However, vitamin C only removes chlorine—it won't filter out heavy metals, PFAS, or other water contaminants. For comprehensive filtration, you'd need a certified shower filter on your bath faucet or a whole-house water filtration system.
Will bath filter removes lead?
None do, to my knowledge, and that’s probably OK. That’s because lead, bad as it is, doesn’t get into the body through water absorption by the skin. It also isn’t aerosolized into steam, meaning you won’t breathe it in. The main way lead gets into the body is by drinking it, which is why it’s important to use a water filter for your drinking water. So, be careful not to drink bath water if you have lead pipes. If you are still concerned, you can install a whole-house water filtration system that is certified to remove lead, or have lead pipe remediation done.
Do bath filters remove fluoride?
No, bath filters cannot remove fluoride. Fluoride is an extremely difficult contaminant to filter and requires specialized filtration methods like reverse osmosis operating at cold temperatures with very slow flow rates. The small size of bath filters, combined with hot water and high flow rates, makes fluoride removal impossible. If fluoride removal is important to you, you'd need a whole-house reverse osmosis system or at minimum, a certified fluoride filter for your drinking water. That said, fluoride is not absorbed through the skin, so you probably do not need to prioritize this anyway!
Can bath filters remove heavy metals?
No.
Here’s why: let’s say you have Arsenic in your water supply (as many cities do)— a KDF filter that advertises that it can remove Arsenic may sound like a good fit, but, it may only remove say, 1 molecule of Arsenic, once, in the first use. A larger activated carbon block that filters cold water moving through it at a moderate kitchen tap water rate can remove more, if pH conditions are right and other contaminants aren’t inhibiting it. A shower filter will remove far less because of the relatively small size (meaning smaller amounts of carbon), the hot temperature of the water, and the great force and speed it’s pushed through at, and a tub filter would remove even less. There simply isn’t enough time for the media to capture contaminants, and heat changes the ability for contaminants to bind to it, as well. A whole-house Reverse Osmosis system would be the only way to meaningfully decrease bathtub water levels of Arsenic.
Do you absorb arsenic from taking a bath?
No. Drinking water with arsenic is the main way it get into your body. Arsenic has poor dermal absorption, and while you can breathe it in from dust, your tub water would have to be 1,137°F for it to become aerosolized into steam for inhalation. So, prioritize removing arsenic from your drinking tap water instead. Some tub filter brands advertise they can remove arsenic, but this is likely just to make them appear more effective.
Can bath filters remove PFAS?
No. A shower filter that you use on your bath spout can, but only if it is tested and certified to be able to. The certification is NSF/ANSI 53, and you should also see results showing exactly how many PFAS were removed and for how long. Here is an example.
Can you absorb PFAS through bath water?
Unfortunately, it is looking that way. Studies are starting to trickle out revealing this is more of a problem than we previously thought. Tap water is contaminated with PFAS in about half of the water supplies in the US, and as “forever chemicals” they are very difficult and expensive to remove at the municipal level. PFAS are linked with obesity, cancer, and immune system dysfunction. Although the primary way we’re exposed to PFAS is through ingesting them, PFAS in tub water concerns me for two reasons:
Higher exposure time: if you’re like me, you can spend a looooong time in a tub, reading.
PFAS are still a new chemical that we are learning more about every day. We understand really well exactly how say, aluminum, moves through the body, but we are still being surprised constantly by what PFAS are capable of. I would not be surprised if we continue to find out that skin absorption is more of an issue than we thought. That said, we only know a little so far!
How often should you replace bath filter cartridges?
Most bath filter manufacturers recommend replacing cartridges every 2-3 months or after 200-300 baths, whichever comes first. However, this frequency depends heavily on your water quality and how much filtration media is actually in the filter. Smaller bath ball filters with minimal media may become saturated faster, while larger inline filters like the Canopy might last longer. Hot water, high mineral content, and high chlorine levels all reduce filter lifespan. If you notice your water starting to smell like chlorine again or developing an odor, it's time to change the filter regardless of the manufacturer's timeline.
Can I use a bath filter with a handheld shower head?
Yes, and this is actually one of the most effective bath filtration methods. You can attach a shower filter to your handheld shower head and use it to fill your tub. The slower flow rate through a shower filter (compared to a bath faucet) gives filtration media more contact time with contaminants, improving removal efficiency. The main drawback is that water may cool slightly as it travels through the hose into the tub, so you'll want to start with hotter water. This method works particularly well if you already have a shower filter that's certified to remove chlorine, PFAS, or other contaminants.
Are bath filters better than whole house water filters?
No. Whole-house water filtration systems are significantly more effective than bath filters because they treat water at cold temperatures with much larger amounts of filtration media and slower flow rates—all conditions that improve contaminant removal. A properly certified whole-house system can remove chlorine, heavy metals, PFAS, and other contaminants from all water sources in your home, including bathtubs, showers, and drinking water. Bath filters are a compromise solution if whole-house filtration isn't feasible, but they're limited by small size, hot water, and high flow rates.
Do bath filters work for well water?
Bath filters are not designed to address the specific contaminants commonly found in well water, such as bacteria, nitrates, iron, sulfur, or high mineral content. Well water needs to be tested first to determine which contaminants are present, then treated with appropriate filtration or treatment systems—often whole-house solutions. If your well water contains high chlorine (from private treatment), a bath filter might reduce some of it, but for comprehensive well water safety, you need testing and properly certified filtration systems rather than a simple bath filter.
Can bath filters help with eczema or dry skin?
Bath filters that remove chlorine may help reduce skin irritation for people with eczema or sensitive skin, since chlorine can strip natural oils and cause dryness. However, other factors like hard water minerals (calcium and magnesium) also contribute to skin issues, and most bath filters don't remove these minerals. For eczema relief, removing chlorine is a good first step—either with a filter, shower filter on your tub faucet, or vitamin C powder. For hard water issues, you'd need a water softener or whole-house system.
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