How Much Can a Water Filter Do? (2023)

How Much Can a Water Filter Do? (1)

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Lead, bacteria and PFAS are among the contaminants cropping up in drinking water.

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By Dana G. Smith

Over the past few years, water safety crises have cropped up in several cities, including Baltimore, Flint, Mich., Jackson, Miss., and Newark, N.J., where lead or bacteria have leached into tap water, forcing people to rely on bottled water or on boiling their tap water to rid it of pathogens.

In Wilmington, N.C., high levels of perfluoroalkyl and polyfluoroalkyl substances, chemicals commonly known as PFAS, were detected in the local watershed. PFAS have been linked to a host of health issues, including cancer, liver damage and problems with fertility. The Environmental Protection Agency proposed new regulations in March that would crack down on drinking water levels of six types of PFAS, substantially lowering the allowable detectable amounts. (Drinking water is not the only source of exposure to PFAS, which show up in food wrappers, cooking pans and waterproof clothing, among other places, but reducing contact wherever possible is advisable.)

These events raise questions about just how safe municipal water supplies in the United States are, and whether additional filtration steps are required even outside of areas experiencing an acute crisis. And if that’s the case, are there home water filters that will help?

Problems with the system

Water sanitation is often listed as one of the greatest health advancements of the 20th century, helping to significantly reduce the death rate from infectious diseases. Water safety standards were enshrined in the Safe Drinking Water Act of 1974, which gives the E.P.A. authority to restrict the amounts of many metals, bacteria, pesticides and other harmful contaminants that can be detected in water. State agencies monitor water treatment plants to ensure they are adhering to the law, and if any violations emerge, they are required to notify consumers within 24 hours. (Owners of private wells are responsible for ensuring that their water is free of contaminants.)

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How Much Can a Water Filter Do? (3)

Since the passage of the Safe Drinking Water Act, though, other water-monitoring issues have arisen. For example, most water treatment plants are not set up to remove more modern contaminants, such as PFAS, pharmaceutical drugs and endocrine disrupting chemicals, said Detlef Knappe, a professor of civil, construction and environmental engineering at North Carolina State University, who was one of the first to publish on the Wilmington PFAS problem.

Another concern is whether we are “setting standards at a pace that is reflective of what we know about the science of our water,” said David Cwiertny, a professor of civil and environmental engineering at the University of Iowa. He gave the example of nitrate, an agricultural pollutant that’s present in the water supply in Des Moines. While the local water treatment plant takes steps to remove the contaminant, there are questions about whether the allowable levels could still cause health harms.

Aging infrastructure is also a problem. In several of the recent crises, contamination occurred when lead leached into the water as it traveled through the distribution pipes. National regulations about the amount of lead permitted in pipes have been strengthened over the years, but many old water distribution systems have not been updated and contain unsafe levels.

“Often, things go wrong because of just underinvestment into this type of infrastructure,” Dr. Knappe said. “The rate at which we’re replacing the distribution system pipes in the network is not keeping up with the rate at which the system really needs to be maintained.”

Finally, experts say water treatment plants are not equipped for the extreme weather events that have become more common with climate change. That was part of the problem in Jackson, where flooding caused by heavy rains overpowered one of the city’s treatment plants, resulting in untreated, bacteria-laden water traveling to people’s homes.

The crises in Flint, Baltimore, Jackson and Newark are currently exceptional cases — public water supplies in the U.S. are generally safe, said Thanh Nguyen, a professor of civil and environmental engineering at the University of Illinois, Urbana-Champaign. But “the number of exceptions may increase with time if we don’t” update the infrastructure, she said.

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What home filters can do

If there is a known crisis in your area, local officials will provide recommendations for how best to keep yourself safe. If you’re generally concerned about potential contaminants, at-home water filters can help with some issues.

Most filters contain activated carbon to capture contaminant particles, which can be used in pitchers, refrigerator dispensers, faucet attachments or systems installed under the sink. Activated carbon is good at removing many chemicals and metals but not all (it doesn’t capture nitrate, for example), and it cannot filter out most bacteria.


The American National Standards Institute and NSF International — two independent groups that evaluate product performance — have established standards for water filters. Companies aren’t required to make products that meet NSF/ANSI standards, but because “there is no federally regulated requirement,” certification can help to “ensure that the product isn’t a counterfeit or it’s actually effective,” said Kyle Postmus, senior manager of the Global Water Division at NSF.

NSF/ANSI Standard 42 is for aesthetics, such as taste, smell and appearance (people often want to filter out traces of the disinfectant chlorine). Standard 53 focuses on safety, ensuring levels of lead or mercury, as well as some pesticides and industrial chemicals, are below the accepted limit. The certifications are for individual contaminants, and the product should specify all the contaminants it is approved to reduce.

Home filters appear to work decently well for PFAS and can now be NSF/ANSI Standard 53 certified for some of those chemicals, too. In a study published in 2020, Dr. Knappe and his co-authors found that, on average, pitcher and refrigerator filters that use activated carbon reduced PFAS levels by about 50 percent. More advanced filtration systems that use a process known as reverse osmosis were over 90 percent effective, but they are much more expensive and waste a significant amount of water.

Sometimes filters can cause more harm than good. Dr. Nguyen’s research revealed that if water sits in a faucet or under-sink filter for a long period of time, such as overnight, it can actually pick up more contaminants, including lead and bacteria. That’s because the water is essentially bathing in high concentrations of the particles that were trapped by the activated carbon. When the faucet is turned on again, the contaminant-infused water comes rushing out. As a result, Dr. Nguyen said that it is important to flush your water filter for at least 10 seconds before drinking from it. Also, be sure to change your filter regularly.

Most of the experts interviewed for this article said that they used an at-home filter, but none said it was essential. Some used filters for taste issues, while others said it was a precautionary measure. “Not everybody needs them, but I can think of a lot of reasons why people might,” Dr. Cwiertny said. “What I would encourage is that people make informed decisions and know why they’re purchasing a device” — for example, for a specific taste concern or for filtering out a known contaminant.

If you’re worried about the quality of your water and want to know whether you should invest in a filter, you can use a home test kit. You can also request a Consumer Confidence Report from the E.P.A. that will detail what’s in the water when it leaves your local treatment plant, although the report does not account for what the water might encounter as it travels through the distribution pipe network.

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The experts cautioned that if your region has a known issue with lead or another contaminant, a filter is a bandage on a wound that needs surgery — the larger problem with the pipes or water supply still must be addressed.

Dana G. Smith is a reporter for the Well section, where she has written about everything from psychedelic therapy to exercise trends to Covid-19.


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How Much Can a Water Filter Do? ›

In a study published in 2020, Dr. Knappe and his co-authors found that, on average, pitcher and refrigerator filters that use activated carbon reduced PFAS levels by about 50 percent.

How effective is a water filter? ›

No filters or treatment systems are 100% effective in removing all contaminants from water, and you need to know what you want your filter to do before you go shopping (see Step 1). Not all filters of a particular type use the same technology, so you should read the label carefully.

How much water can a water filter hold? ›

The capacity of water filter systems vary. A quality, durable and effective product can range from 4,000 gallons through 1 million gallons. The flow rate of a system will likely be measured in gallons of water per minute.

How long will a 5000 gallon water filter last? ›

It's good for up to 5,000 gallons. That's about 2-1/2 to 3 years for an average family of four.

What do water filters not remove? ›

It will not remove bacteria. To remove naturally occurring or disinfection tastes and odours from water an activated carbon filter is more appropriate. It will not remove bacteria. To remove chemicals and bacteria, a reverse osmosis or distiller system would be required.

What problems do water filters solve? ›

Water Filters remove unwanted impurities from water such as sediment, taste and odour, hardness and bacteria to result in better quality water.

Does a water filter make water drinkable? ›

A water filter is a device that you can use to remove many kinds of contaminants and impurities from your drinking water. A water filtration system could either use a chemical, a biological process, or a physical barrier to filter your drinking water. This is to make sure that it is safe to drink.

How long does it take water to filter through a filter? ›

This all depends on your water quality. On average, it initially takes 10 to 15 minutes to filter from the top reservoir to the bottom.

What happens if you overuse a water filter? ›

Contaminant Build Up

And aside from sediment, a carbon water filter that is used beyond its days can collect a build-up of other materials and contaminants. This build-up of contaminants often looks like 'goop' and can even leak into your supply of drinking water.

How long should you filter water? ›

Consider your water filters as a whole on a one year cycle

The frequency at which you need to perform this chore varies depending on your usage and the quality of your source water. However, a good rule of thumb is every 3-6 months.

How do you filter large amounts of water? ›

Countertop filters are best for filtering large quantities of water without modifying plumbing. They're less likely to clog than carafe or faucet-mounted filters, but can clutter countertops and can't be used with all types of faucets.

How long does a 20000 gallon filter last? ›

Recommend replace filter every 20000 gallons for 5 Years for better filtration. ICEPURE filter use advanced and precise measurement technology, combined with 3D multi-dimensional design technology to ensure that our products fully match and do not leak water.

How long does a 20000 gallon water filter last? ›

Replace filter cartridge every 20,000 gallons, when there is a noticeable drop in water flow, when water has unpleasant taste or odor, or every six months, whichever comes first.

What are the cons of water filters? ›

The Cons of a Water Filtration System:
  • Speaking of cost, initial installation is more expensive than other filtration methods. ...
  • You can't pick and choose what gets filtered. ...
  • Fluoride and your teeth: If you choose a whole house water filtration system that removes ALL chemicals, you will also be removing fluoride.
Apr 12, 2019

Is filtered water better for you than tap water? ›

In conclusion, filtered water is healthier. A quality water filter independently tested for the type of tap water in your household will reduce risk and thus likely have long term health benefits.

Should you filter tap water? ›

The levels of chlorine in the drinking water are non-toxic, so you may not need a filter. However, consumption over time may have health consequences.

What are two things that even the best filter will not remove from water? ›

It is important to note that carbon filters do not have the ability to remove inorganic pollutants such as nitrates, fluoride, and arsenic.

Why do water filters waste so much water? ›

For every 1 liter of filtered water, an average RO water purifier wastes approximately 3 liters of water. While the purifier has numerous advantages, it wastes water due to its membrane technology, which necessitates the use of additional water to clean the filter, which is then discarded.

Why water filtration is a problem? ›

Perhaps the most common problem encountered by residential water filtration systems is a dirty filter. This lets chemicals and heavy metals to find its way into drinking water. There are different types of water filtering systems, each of which has its own requirements for maintaining the filter.

What is the cleanest water to drink? ›

Mineral, structured, and pure spring water are some of the healthiest water you can drink because they're clean and contain all the essential minerals your body needs. Filtered water removes contaminants but might also remove essential minerals.

Is Bottled Water better than filtered water? ›

Although both filtered water and bottled water can provide healthier, better-tasting water, the cost-effectiveness and smaller environmental impact of filtered water beats out bottled water at every turn.

What is the healthiest drinking water? ›

What Is The Healthiest Water To Drink? When sourced and stored safely, spring water is typically the healthiest option. When spring water is tested, and minimally processed, it offers the rich mineral profile that our bodies desperately crave.

Can you drink water right after changing filter? ›

Although drinking it won't hurt you, most people prefer to run water through the filter because of the bitter taste carbon can leave in your mouth. Flushing your newly installed refrigerator water filter is easy!

What does Brita not filter out? ›

For example, the Brita water filter pitcher uses a coconut-based activated carbon filter that removes chlorine, zinc, copper, cadmium and mercury. However, activated carbon filters don't remove all nitrates, dissolved minerals, or bacteria and viruses in water through the absorption process.

Can you drink water right away after changing filter? ›

Therefore, the first few glasses of water that you dispense after installing your new fridge filter may contain bits of carbon which can cause your water to look cloudy and gray. Don't worry, the carbon bits will not harm you if you ingest them, but they will make your water taste bitter.

What is the negative effects of filters? ›

“The more people engage in self-objectification, the less they're able to feel their emotions and body sensations. Their attention span goes down, which has a numbing effect.” If you spend time using filters or editing videos of yourself, you may be familiar with that numbness. It doesn't feel good.

Why does water taste bad after changing filter? ›

Water tastes bad after a filter replacement because the filter itself contains fumes, grease, and debris. By running the water for a few minutes, the impurities present in the filter will be rinsed or flushed out removing any and all contaminants that could give water a bad taste.

Can water filters grow mold? ›

One of the most recurring problems with water filters across all brands is the growth of mold and the constant combat of that. Most mold is harmless but having mold in your drinking water could present serious hazards to your health. And of course, if you're using a water filter, your aim is to prevent that.

How many gallons does a water filter last? ›

The Brita Standard Filter (white) should be replaced after every 40 gallons or about every two months. The Brita Longlast Filter (blue) needs to be replaced after every 120 gallons, or approximately every six months.

How often should you filter your whole house water? ›

Whole House Filters

To maintain the best quality and reliability of your whole house water filter, it is recommended that you change it every three to six months. This helps to keep the water free from impurities and contaminants that can be harmful to your health, your home's plumbing system, and your appliances.

How long does it take for kidneys to filter water? ›

These unsung heroes of human physiology perform a remarkable task. They are capable of filtering a huge amount of blood. Normal kidneys will filter about 100-120 ml of water per minute. This varies a bit depending on your height and weight, but these numbers will serve us well for our numerical example.

What can filter 50 gallons of water a day? ›

A single adult oyster can filter more than 50 gallons of water a day. Along the U.S. East Coast, Bricker and her colleagues are measuring the amount of nutrients removed by oysters to help states develop nutrient management plans that include oyster farms.

Which water filter removes the most contaminants? ›

Reverse Osmosis Systems

A reverse osmosis system combined with a carbon filter is most effective at removing water contaminants.

How long does a 16000 gallon filter last? ›

When used with municipal water, this under sink water filter serves a life of 16,000 Gal. or 24 months. Ultra-long service life: when used with municipal water, each filter has a maximum service life of 24-months or 16,000 Gal.

Can a water filter last 5 years? ›

Filters in residential settings should be changed every 6 to 12 months. Reverse osmosis, membranes, and additional alkalisers only need to be changed ever 2 years or 4 years, respectively.

Is a 20 gallon filter too big for a 10 gallon tank? ›

depends on the stock you are keeping. generally using filters rated for 3 to 4 times bigger than the tank is fine. any more than that isn't good.

How long does a 300 gallon water filter last? ›

If you have a FB300 tank, it should be replaced every 3 years or 300,000 gallons of water. If you have a FB1,000 tank, it should be replaced every 10 years or 1,000,000 gallons of water.

How much water filter capacity per hour? ›

Water Filtration System, Capacity: 500-1000 litres per hour
Capacity500-1000 litres per hour
Voltage380 - 440V
Phase3 Phase
Power SourceElectric
Frequency50 - 60 Hz
1 more row

How many gallons per hour should your filter be able to clean? ›

Flow rate is measured in gallons per hour, or GPH, measured by the amount of water that will run through the filter in one hour. We recommend that the filter has a GPH at least 4-6 times the tank volume. For example, a 20-gallon tank should have a filter with an 80-120 GPH.

Is whole house filtration worth it? ›

If you need chlorine-free water 24/7 for your bathing and washing, a whole house water filter will be worth the investment. But if you just need your shower water to get filtered, a shower filter will also be good enough.

Do water filters save money? ›

What's the annual cost of bottled water versus using water filters? It's about $80 cheaper to use a water filter in the first year than it is to buy bottled water for a household. You save even more the following year when all you're doing is replacing the filter at regular intervals.

Do all water filters waste water? ›

Through the filtration process, some amount of water is inevitably wasted, but how much is important. In fact, water filtration often comes at a high cost: most reverse osmosis systems waste as much as 20 gallons of water just to produce 1 gallon of filtered drinking water.

Is boiled water the same as filtered water? ›

The overwhelming conclusion is that filtered water trumps boiled water. Boiling water isn't enough to completely purify the water because it leaves harmful contaminants such as lead and chlorine in there.

Is A Brita filter worth it? ›

Brita Standard

Brita is probably the best-known of the water filter pitcher brands and it performed well in our testing, second only to the ZeroWater in the overall removal of dissolved materials. The Brita removed about 40% of the TDS. Not a bad showing but still significantly less than the winner.

Why does filtered water taste so much better? ›

Filtered water generally tastes better than plain tap water, due to reduced impurities, which also means that you can enjoy better tasting drinks like tea and coffee, not to mention less limescale build-up in your appliances. You'll also be able to enjoy richer flavours in the meals you cook.

What is the best way to purify water at home? ›

You can use household liquid bleach (regular household bleach contains 5.25% sodium hypochlorite) to kill microorganisms. Do not use scented, color-safe or bleaches with added cleaners. Add 16 drops of bleach per gallon of water, stir and let stand for 30 minutes.

Can I drink water left out overnight? ›

The growth of bacteria is even high when you store the water in a warm area. You should avoid drinking water left open for a very long time. The water left overnight or for a long period of time in an open glass or container is home to numerous bacterias and is not safe for drinking.

What is the best way to drink water at home? ›

If you don't have safe bottled water, you should boil your water to make it safe to drink. Boiling is the surest method to kill disease-causing germs, including viruses, bacteria, and parasites. adding a pinch of salt for each quart or liter of boiled water.

What are the disadvantages of water filters? ›

The Cons of a Water Filtration System:
  • Speaking of cost, initial installation is more expensive than other filtration methods. ...
  • You can't pick and choose what gets filtered. ...
  • Fluoride and your teeth: If you choose a whole house water filtration system that removes ALL chemicals, you will also be removing fluoride.
Apr 12, 2019

Is water filter better than buying water? ›

Filter water vs. bottled water. Although both filtered water and bottled water can provide healthier, better-tasting water, the cost-effectiveness and smaller environmental impact of filtered water beats out bottled water at every turn.

Are water filters effective against viruses? ›

Do water filters remove viruses? Water filters do not effectively remove viruses. Viruses are too small to be ensnared by filters, with the exception of ultrafiltration. However, even ultrafiltration should be used in conjunction with another water treatment system.

What is the most effective way to purify water? ›

Boiling is the best way to kill disease-causing organisms, including viruses, bacteria, and parasites. The high temperature and time spent boiling are very important to effectively kill the organisms in the water. Boiling will also effectively treat water if it is still cloudy or murky.

Is it worth it to filter tap water? ›

If you suffer with any type of health issue, it's vital you purify water in your home. Not only does filtered water smell and taste better, your body will thank you for it. Water filters are designed to remove almost all contaminants in tap water, although this is dependent on what type of filter you buy.

Can a filter remove bacteria from water? ›

' Water filters do not kill bacteria per se, rather they remove them from your drinking water. Some filters are better at this removal than others – that's why it's important to understand the different kinds of filters as well as which is more effective and why.

Do water filters remove E coli? ›

Ultrafiltration filters remove particles based on size, weight, and charge; Ultrafiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia); Ultrafiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);

What kills viruses in drinking water? ›

Boiling is sufficient to kill pathogenic bacteria, viruses and protozoa (WHO, 2015). If water is cloudy, let it settle and filter it through a clean cloth, paperboiling water towel, or coffee filter. Bring water to a rolling boil for at least one minute.

Can you drink rain water? ›

To lower your risk of getting sick, consider using rainwater only for uses such as watering plants that you don't eat or washing items that are not used for cooking or eating. Avoid using rainwater for drinking, cooking, brushing your teeth, or rinsing or watering plants that you intend to eat.

What is the simplest way to purify drinking water at home? ›

The simplest method to purify water is to boil it for a good time. High temperatures cause the bacteria and virus to dissipate, removing all impurities from the water. In doing so, chemical additions cease to exist in the water.


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