Everyone wants clean water — but the truth is that even water in nature isn’t technically “pure.” That’s why we humans have been improving the taste, odor and appearance of our drinking water since at least 4,000 B.C.
Click here to get more.
Of course, our methods — and the research that guides them — have advanced. Today’s water filtration systems work through sophisticated physical or chemical processes that address different contaminants in distinct ways. Some can even help control your water’s pH.
Read on to see how water filters work, what they do and why it matters.
Water filters work by using physical or chemical processes to reduce contaminants from tap water. As water flows through the filter, impurities like chlorine, calcium and magnesium are either physically blocked, trapped in the pores of the filter or chemically absorbed into the surface of the media.
Different filters are designed to target specific water quality issues. For example, here are some of the most common water filtration processes and how they work:
Here are some of the most common water filtration processes and how they work:
Reverse osmosis is based on a naturally occurring process responsible for helping plants absorb water from soil. This is called “osmosis,” and it involves a semipermeable membrane separating two amounts of fluid. One side has a higher concentration of solutes than the other. To create a sort of equilibrium, fluid with fewer solutes tries to flow to the other side, moving through the membrane along the way.
In reverse osmosis filtration, this process happens backward: An outside force or pressure causes the fluid to move in the opposite direction, or against the “concentration gradient.” As this occurs, solutes like salt are left on one side of the membrane and filtered water flows into the other. That’s why RO is often used for seawater desalination as well as everyday filtration.
It’s important to keep in mind that the reverse osmosis process itself is often only one part of what’s actually happening in an RO drinking water filtration system. The best solutions combine RO with other filters and processes to catch different kinds, sizes and amounts of contaminants.* Some even have optional filter cartridges that put you in control of your water’s pH.
In this type of filtration, carbon or activated carbon forms the basis for a process called adsorption, not to be confused with absorption:
That one letter makes a big difference. Because carbon filtration uses adsorption instead of absorption, certain tiny materials stick to the carbon while the rest of the water flows through. This solution is a good fit for chlorine, sediment, certain organic compounds and some other contaminants, but it may not catch other materials that could potentially cause aesthetic and health concerns.
Activated alumina (AA) is a porous material made from aluminum oxide. An AA water filter works in much the same way as carbon filtration; however, it’s perhaps a bit more complicated — and that means its benefits can be a bit less reliable, too. For example, while AA filters are often a good fit for particular water quality problems such as fluoride or arsenic, the effectiveness of the filtration process relies on the AA material itself, plus the pH and material makeup of your water supply. Some people are also concerned that the main component of AA, aluminum, may leach into the water under certain circumstances.
Mesh filtration is perhaps the easiest to picture. It relies on tightly woven layers of wire cloth, creating a sort of trap that’s generally most effective for sediments such as sand and dirt. Mesh filtration on its own can’t catch certain contaminants or impurities, particularly those that have dissolved in the water.
You may notice that this process is somewhat similar to reverse osmosis. While it’s true that many kinds of filtration rely on the same basic concepts, keep in mind that RO membranes are designed differently and often installed in systems with other filter media.
Although a simple water pitcher filter may rely on just one kind of filtration, some of the best systems unite different solutions for a more comprehensive, complementary treatment process. RO is one example of this, but a more familiar application may already be connected to your house: treated city water.
Cities have varying approaches to water treatment, sometimes because relevant governing bodies have established different water quality guidelines (like Water Quality Standards in the U.S. and the Guidelines for Canadian Drinking Water Quality in Canada). However, many cities use this combination of filtration methods:
Remember, private wells don’t have this kind of water treatment, which is why fluoride and chlorine issues are less common there while others, like high iron or hydrogen chloride levels, are more common. That’s not to say that filtration is only for wells, though; treated city water can still have problems from issues such as hard water or contaminants that are not yet federally regulated, like PFAS in water.
In many ways, filtration is a step you add to the water cycle. Think about the way water moves through ecosystems: It exists as precipitation, snowmelt and runoff and can gather in lakes, rivers, aquifers and more. In all of these stages and locations, it has plenty of opportunities to pick up minerals, sediment and other materials — and in nature, that’s not necessarily bad. It only becomes a problem when that unfiltered water ends up in your glass.
Filtration is able to address these concerns from any source or water system. After all, it’s not just nature that impacts your water quality; other elements — such as corrosion in your home’s piping or chlorine added to municipal water — can also play a role. That’s why it’s helpful to think of filtration as the last step of your water’s journey before it ends up at your tap.
Broadly speaking, a water filter’s job is to address and reduce a wide range of potential problems. Depending on the type of filter, these may include:
How exactly a filtration system achieves this depends on its size, structure and complexity — but the goals are generally similar:
Filtration and softening aren’t interchangeable. The former addresses specific contaminants and water quality issues based on the filtration media or mechanism, and it has benefits such as clearer water and reduced taste issues. The latter removes different materials — like the calcium and magnesium that cause hard water — using resin beads and a saltwater “recharge” process that isn’t part of filtration. Softening doesn’t address taste, odor and appearance issues, but it can help solve hard water problems such as mineral deposits, spotty dishes, dry skin, brittle hair and more.
It’s important to note that filtration and purification aren’t the same thing, especially when it comes to at-home water treatment. Generally speaking, purification is a more involved process that makes water usable for medical, industrial and other purposes. Household tap water for drinking, cleaning, cooking and bathing is usually well-suited for regular filtration — as long as you choose the right filtration system, that is.
Luckboil contains other products and information you need, so please check it out.
As you research house filter options, you’ll quickly notice that there are two primary types of filtration: physical and chemical. These can differ widely — not just in size, price and functionality, but also in comprehensiveness. That’s why it’s helpful to understand the basic mechanics of different filtration types and what they do in practice.
Physical filtration uses a physical barrier to block, trap or catch certain solid debris. It’s the kind of water treatment early civilizations likely used, although in a much simpler form than today’s filters, and you can see it for yourself: Just find a muddy river, dig a hole deeper than the water level and watch cleaner water filter up through the sand or dirt.
To get the job done, a physical filtration system needs certain components:
The biggest difference in chemical filtration is that it doesn’t use the same kind of barrier. Instead, it relies on filtration media — that is, an active material that attracts or otherwise traps some contaminants through chemical interactions. For example, in a carbon or activated carbon filter, the medium traps or “adsolves” dissolved materials as they pass through, thereby reducing their presence in the water supply.
Chemical filtration systems need many of the same components as their physical filtration counterparts. However, because each chemical medium type only reacts to or with certain contaminants, these systems may not be as comprehensive on their own.
Now that you understand how water filters work, it’s time to choose one that fits your needs. However, that may be easier said than done. That’s because some contaminated water problems can’t be seen, smelled or tasted — and other issues, such as discoloration or bad odors, can have multiple causes.
To ensure you get the right filtration solution for the right purpose, it’s smart to begin with a professional water test. Your local water expert will test for chlorine, iron, total dissolved solids (TDS) and more — and in about 30 minutes, you’ll have the answers you need. You’ll even get personalized recommendations to help you choose the best house water filter system.
Testing your water to find out whether there are harmful germs or chemicals in it will help you choose a filter. If your water is free from harmful germs or chemicals, you may decide you do not need a filter. If your water has harmful germs or chemicals, choose a filter that removes those germs or chemicals.
If you get your water from a private well or a rainwater collection system, test your water at least once each year for harmful germs and chemicals. Also consider testing your water if you notice changes in color, taste, or smell.
Contact your health department for advice about what to test for and how to find a state-certified lab to do the testing.
If you get tap water from a public water system, review the water quality report your utility must provide every year. The report will show if there are harmful germs or chemicals in your water.
The pore size is the size of the tiny holes in a filter that let water through. Filters work like strainers or colanders. As pore size gets smaller, fewer types of germs and chemicals get through the filter.
If a filter has an absolute pore size of 1 micron, for example, each one of the filter's pores is 1 micron or smaller. This means that anything larger than 1 micron will be caught in the filter and removed from the filtered water.
Filters with a nominal or mean pore size of 1 micron have an average pore size of 1 micron. This means that some pores are smaller and some pores are larger than 1 micron. These filters will let some things that are bigger than 1 micron through the larger holes.
NSF International is an independent organization that develops public health standards for products. One way to figure out what a water filter removes is to look for an NSF certification on the filter's label. You can look up specific products in the NSF database to see what they are certified to remove from water.
Some of the NSF standards related to water treatment are:
Point-of-use filters usually filter water in batches and deliver it to a single tap, such as your kitchen sink. These include under-sink filters and those that attach to your faucet. Consider point of use filters if you only need to filter the water you drink and cook with, for example.
Whole-home filters, also called point-of-entry filters, filter water as it comes into your home. This means all your water, from every tap, gets filtered.
Consider these filters if you need to remove a harmful substance, such as certain volatile organic chemicals, from all your water. This includes water you use to bathe or clean with, as well as water you drink or cook with.
Keep in mind that if you install a whole-home filter that removes chlorine or other disinfectants, more germs may grow in your plumbing.
You will need to maintain any filter you use to keep it working properly and prevent germs from growing in it. This includes regularly changing the filters according to the manufacturer's recommendations. Wear gloves while you change filters and wash your hands afterward to avoid getting sick.
Some filters also require pre-treating water before you filter it to protect the filter and make sure it works properly. Examples of pre-treating include adjusting pH or adding powdered activated carbon.
For more information, please visit Water Purifier manufacturer.