A home water filtration system is a device or set of devices that helps remove harmful chemicals and germs from the water in your home. Depending on the type of filter, it can improve the safety, taste, and smell of the water you drink, cook with, and bathe in.
Not every home needs a water filtration system. Whether you do depends on things like the quality of your water and the health of your immune system.
How Do Home Water Filtration Systems Work?
“Home water filtration systems work by using various physical and chemical processes to remove contaminants from water as it passes through the system,” says Kyle Postmus, a senior manager at the National Sanitation Foundation (NSF), a nonprofit that helps set safety standards for food and water.
These systems use substances like activated carbon and technologies such as reverse osmosis, which pushes water through a special filter that blocks things like salt, chemicals, and germs. As water passes through the filter, contaminants get trapped on the surface of the filter or in tiny holes called pores.
“What these symptoms filter depends on their design and technology, but they can address a wide range of contaminants,” Postmus says. Chlorine, heavy metals like lead and mercury, pesticides, and germs are just some of the substances water filtration systems can remove.
What is pore size?
Pore size is the size of the tiny openings in a water filter. It determines what the filter can block. Smaller pores catch more contaminants, such as chemicals and germs, while larger ones let more through.
Pores are measured in units called microns. A micron is very tiny — one-thousandth the size of a millimeter. It’s so small that a single strand of hair measures 100 microns wide. The pore sizes of home water filtration systems usually range from 0.0001 microns to 5 microns, depending on what the filter is designed to block.
What Are NSF ratings?
The NSF sets standards and performs tests to ensure that your water supply is safe. Any water filter that is NSF certified has been thoroughly tested to confirm that it works the way the manufacturer claims it does, and that it’s safe to use.
“It’s the gold standard for ensuring that the filters you buy are actually doing their job,” says Scott Bartell, PhD, professor of environmental & occupational health at UC Irvine Joe C. Wen School of Population & Public Health in Irvine, California. You can look up NSF-certified water filters on their list of approved products.
What Do Home Water Filtration Systems Filter?
Exactly which substances get filtered out depends on the type of system you buy. Home water filtration systems may remove:
- Parasites like giardia and cryptosporidium
- Bacteria like salmonella and E. coli
- Chemicals such as arsenic, barium, cadmium, lead, and sulfate
- Minerals like calcium, chloride, chromium, magnesium, and sodium
- Volatile organic compounds (VOCs), harmful gases that can cause health problems
Some, but not all, filters help lower the amount of toxic PFAS in your drinking water. PFAS stands for per- and polyfluoroalkyl substances. These are human-made chemicals, often called forever chemicals, because they stay in your body and the environment for a long time. They’re linked to health problems like high cholesterol, kidney and testicular cancer, and pregnancy issues like preeclampsia.
What’s the difference between point-of-use filters and whole-home filtration systems?
These two types of home water filtration systems differ based on where you install them and how much water they filter:
Point-of-use (POU) filters clean the water at a single source, such as under your kitchen sink or inside your refrigerator. They only filter the water that comes out of that faucet, which may work well if you only want to filter the water you drink or cook with.
Whole-home filtration systems clean all the water that enters your home, including what comes out of every tap, shower, and bathtub. These are also called point-of-entry (POE) systems and work well if you want clean water from every tap.
Whole-home systems are more expensive than point-of-use filters. And because many of them remove the disinfectant chlorine from water, they may allow bacteria to grow in the pipes.
“The choice between POU and POE depends on your specific water quality concerns, budget, and whether you need filtered water for specific uses or throughout your entire home,” Postmus says.
What Are Some Types of Water Filtration Systems?
Home water filtration systems vary based on how they work and what substances they filter out.
Pitcher water filters
Pitcher water filters clean the water you drink and cook with. They typically contain a carbon filter that removes harmful substances like lead and some PFAs. These filters make water taste and smell better, but they don’t filter out germs. A pitcher filter is more affordable than one you install under the sink.
Refrigerator water filters
Like pitcher water filters, the one that’s built into your refrigerator uses a carbon filter to improve the taste and smell of your water. But it may not filter out many contaminants. You’ll also need to change the filter regularly for it to work properly.
Faucet water filters
This type of filter attaches to your faucet. Depending on the one you buy, it may improve the smell and taste of the water and remove contaminants like like chlorine and lead.
Activated carbon filters
These are the filters you’ll find in refrigerators, pitchers, and faucet attachments. The carbon attracts and attaches to contaminants in the water. Carbon filters remove chlorine, VOCs, pesticides, some PFAS chemicals, and other substances that affect the water’s taste and smell.
“Certain contaminants stick to the carbon and stay in the filter as the water passes through,” Bartell says. “Eventually the contaminants ‘break through’ the filter, though, so it’s important to change the filter periodically.” Follow the manufacturer’s instructions for how often to replace the filter.
Reverse osmosis filters
This is a more advanced technology – the same one that removes salt from ocean water to make it drinkable. Reverse osmosis filters push the water through a semipermeable membrane – a barrier that blocks larger particles from getting through. These filters can remove up to 99% of dissolved contaminants, including lead, arsenic, and fluoride. They are also effective for removing pesticides from water. The water that remains after this process is cleaner to drink.
“Generally speaking, reverse osmosis is the most effective technology for removing almost every type of contaminant,” Bartell says. “But it is also the most expensive.”
Another downside to reverse osmosis filters is that they waste a lot of water, which goes down the drain. Some of these systems also remove healthy minerals like calcium, iron, and magnesium from drinking water. The company that makes the system may offer drops or a cartridge to replace some of the minerals that are lost.
Ion exchange filters
Ions are atoms that carry an electric charge. Ion exchange filters replace harmful ions with less harmful ones. They remove chemicals, minerals, and heavy metals from the water.
Distillation filters
This process filters germs, minerals, and some chemicals out of your home’s water using heat. Boiling the water produces steam. As steam cools back into water, many contaminants are left behind. Home distillation systems are less common than other types because they require more energy.
Nanofiltration, ultrafiltration, and microfiltration filters
These terms refer to the pore size and what substances the filter can remove.
Nanofiltration has very small pores – between 0.008 to 0.01 micron. It removes parasites, bacteria, and viruses, and some chemicals.
Ultrafiltration filter pores are between 0.001 and 0.05 micron in size. They remove parasites, bacteria, and some viruses but leave chemicals behind.
Microfiltration filters have pores that range in size from 0.05 to 5 microns. They can remove parasites like giardia and cryptosporidium but not viruses such as norovirus and chemicals like lead.
How to Choose the Best Water Filtration System for Your Home
The ideal water filter for your home depends on what substances you want it to remove, your budget, and other factors. “As a starting point, I recommend consumers check their local water quality report to find out what exactly is in their water that they would like to filter out,” Postmus says. “Narrow the search from there to filters that are able to remove those things.”
If you’re not sure where to start the process, read your water supplier’s consumer confidence report (CCR). This quality report will tell you what contaminants are in your home’s water.
The next step is to find the right filter. On the NSF database, you can look up what substances each brand and type of filter is certified to remove.
You can also reach out to companies that install home water filtration systems for advice. They’ll test your water and suggest the best filter for your home. Home water testing is especially helpful if you live in an older home that may have lead pipes or if you have a private well that isn’t routinely being tested by a public water provider.
Takeaways
A water filtration system removes germs, chemicals, and other contaminants from your water to make it safer and to improve its taste and smell. Whole-home water filtration systems filter all the water as soon as it enters your house, before it reaches any tap. Point-of-use systems are installed in specific taps. Many refrigerators come equipped with water filters. You can also purchase pitcher filters to use for drinking and cooking water.
FAQs About Home Water Filtration Systems
How much does a whole-house water filtration system cost?
The cost of a whole-house water filtration system usually ranges from $1,129 to $3,359. The final cost depends on the type of system and how many filters you need.
Is it worth getting a whole-house water filtration system?
A whole-house water filtration system may be worth it if your water contains harmful germs or chemicals. It helps protect your health by cleaning all the water that comes into your home. But if your water is already safe, you may not need a whole-house system. A smaller, point-of-use filter could be enough and cost less. You can check by testing your water or asking your local water supplier for details.
What is the downside of a whole-house water filter?
The downside of a whole-house water filter is the higher cost and ongoing maintenance. These systems are more expensive to install than point-of-use filters. You may have to spend a lot of money for a system you don’t need.
Do you need a plumber to install a whole-house water filter?
You might need a plumber for most whole house-water filter installations. A licensed professional makes sure the system matches your home’s plumbing, follows local codes, and works properly. While some experienced homeowners may try it themselves, hiring a plumber helps you avoid mistakes and costly repairs.