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Water filters are a necessary household appliance, but with all of the different types and brands on the market, it can be difficult to determine which one is best for you.
In this guide, we’ll outline the different types of water filters available and what each type can do for you and your home. We’ll also provide some tips on how to choose the right filter for your needs. So whether you’re in the market for a new filter or just want to learn more about them, read on!
What is water filter?
Water filters remove impurities such as sediment, taste and odor, hardness, and bacteria from water, resulting in higher-quality water. From improving the taste of drinking water to more specialized applications such as brewing coffee and creating crystal clear ice, we offer a comprehensive selection of filters and cartridges to address a wide variety of water-related issues.
The 5 Types of Filters
There are five distinct types of water filters, depending on the application, i.e. what you’re attempting to remove or, in some cases, prevent:
- Mechanical Filters
- Absorption Filters
- Sequestration Filters
- Ion Exchange Filters
- Reverse Osmosis Filters
Each of these approaches addresses a unique aspect of water filtration, and many filters employ a combination of these approaches to achieve multiple levels of filtration.
How Do They Work?
Water is one of the most vital substances on the planet; it covers 71% of the Earth’s surface and can make up to 75% of the human body. Water is required for various purposes, including agriculture, science, medicine, transportation, heating, recreation, food processing, washing, and, perhaps most importantly, drinking.
For most of us, drinking water comes from a treated municipal supply that is safe to drink. Still, it frequently has unpleasant tastes and odors due to chlorine used to disinfect and disinfect the water. Depending on your location, your mains water may also cause limescale deposits, which can clog pipes and damage appliances.
These two issues, chlorine taste/odor and limescale formation, are just two of many other common water problems that water filtration can resolve. However, how do water filters work in practice?
Mechanical filtration’s fundamental concept is to physically remove sediment, dirt, or other particles from the water via a barrier. Mechanical filters can range from a simple mesh to a ceramic filter with a highly complex pore structure for ultra-fine filtration of pathogenic organisms.
A filter that employs mechanical filtration is typically assigned a micron rating, which indicates how effective the filter is at removing particles of a specific size. Typical ratings you may encounter include the following:
- 5 micron – Removes the majority of visible particles.
- 1 micron – Removes invisible particles without the aid of a microscope.
- 0.5 micron: Cysts will be removed (giardia and cryptosporidium).
Carbon is the most frequently used adsorbent in water filters because it is highly effective at capturing water-borne contaminants. Carbon readily absorbs pollutants due to its massive internal surface, densely packed with nooks and crannies ideal for trapping chemical impurities such as chlorine.
Most household filters contain granular activated carbon (GAC), which absorbs undesirable tastes and odors. Costlier filters employ carbon block elements, which are generally more effective and typically have a micron rating for particle removal.
Carbon for filters can be made from various materials, including wood and coconut shell, with coconut shell filters being more effective and more expensive.
The process of chemically isolating a substance is referred to as sequestration. Polyphosphate made from food grade is frequently used in scale inhibiting filters to trap the calcium and magnesium minerals that cause limescale and corrosion.
However, polyphosphate is typically introduced in trace amounts and acts as a scale inhibitor rather than a scale eliminate. This means that polyphosphate does not soften the water; instead, it keeps the minerals in solution, preventing them from precipitating as scale on any surfaces they come into contact with.
Scale inhibition is not appropriate for all applications due to hard minerals in the water. Rather than that, water softening via an ion exchange process is typically recommended in areas with alkalinity levels of 180ppm or greater (tough water) and applications where water is maintained at a constant temperature of 95°C or greater.
Ion exchange is a technique for softening hard water that involves exchanging the magnesium and calcium ions found in hard water for other ions such as sodium or hydrogen ions. Unlike scale inhibition, ion exchange physically removes the hard minerals, reducing limescale and making the water suitable for applications where a constant high temperature is maintained, such as commercial coffee machines.
Ion exchange is most frequently performed with an ion exchange resin, which is typically available in tiny beads. A similar type of resin is used in some water softeners. In the case of a water softener, the resin is recharged periodically to avoid the resin from becoming ineffective. Because water filters are typically sealed units, you would replace the filter with a new one; however, calcium treatment units (CTUs) can be returned to the supplier and regenerated.
Resins containing sodium ions are not typically used in drinking water filters because the maximum salt (sodium) allowed in drinking water is 200 milligrams/liter. Since sodium ion exchange results in increased salt levels, a hydrogen-based ion exchange resin is preferred for filters.
Reverse osmosis (RO) is a technique for removing dissolved inorganic solids (such as magnesium and calcium ions) from water by forcing it through a semipermeable membrane under pressure, allowing the water to pass through the contaminants to remain.
Reverse osmosis is a highly effective method of purifying water and is frequently used in conjunction with other filters such as a mechanical (sediment) filter and an absorption (activated carbon) filter to return water with a low level of contaminants.
Reverse osmosis systems utilize water pressure to force water through the membrane, eliminating the need for electricity. However, a certain amount of wastewater is generated and disposed of. Due to the additional filters required for multi-stage water filtration, reverse osmosis units can be more expensive than other filtration methods.
However, in applications requiring 99.9 percent pure water, RO provides the highest level of filtration available and is increasingly being used to treat water used in coffee production.
Because each filtration method has a limited capacity for removing contaminants, most water filters or filtration systems employ a combination of ways to achieve the desired water purity level.
To illustrate, household water jug filters will typically incorporate mechanical, absorption, and ion-exchange elements, whereas inline filters will incorporate mechanical and absorption elements, as well as sequestration, if the filter is designed to inhibit scale.
Mechanical absorption and, of course, reverse osmosis can all be used in reverse osmosis systems, depending on the number of stages in the RO system.
By understanding the five distinct methods for filtering water and how they can be combined, you should determine the type of filter required for any given application.
Water filter benefits and health concerns
So, you’re interested in getting a filter for your water? That’s great! Drinking filtered tap water is probably the single most important thing you can do to improve your health. Well… that and regular exercise and proper nutrition, of course. Still, we’ll get to those later. First things first— how do you choose the best filter for your needs?
Let’s start with the benefits. A water filter can improve tap water in several ways which are crucial to your health, including:
- Removing chlorine, fluoride, and other harmful chemicals
- Reducing or even eliminating sediment
- Increasing pH (raising it closer to neutral)
- Bringing heavy metals below detectable levels
- Removing almost all bacteria
If you’ve ever used a Brita pitcher, you might know what I mean when I say it seems like tap water tastes better than bottled water. That’s because your home-made filter was removing the chlorine and other chemicals which typically give tap water an unpleasant taste. You can experience this for yourself by trying to drink a few glasses of filtered and unfiltered water back to back.
But why would you want your tap water to be purer in the first place? After all, it’s already treated at a water treatment facility before coming out the pipe in your house. Well, that’s true… but most municipal water treatment facilities add chemicals which are harmful to your health. Also, they don’t remove things you’d rather not have in your water at all— like bacteria and heavy metals.
Now, the most common argument against tap water is that it contains chlorine and fluoride , both of which are harmful for your health when consumed over a long period of time. Some people say there’s nothing wrong with small doses of these chemicals, because our bodies can handle it. Others disagree, saying that they should be left out completely.
Either way, the only way to avoid these chemicals completely is to filter your water with something like a reverse osmosis system (the best choice) or distilled water (not my favorite solution). Or you could use a pitcher that reduces heavy metals and chemicals, but not bacteria.
If you drink unfiltered tap water over time, it’s possible to build up a dangerous amount of fluoride in your body. Fortunately, filtered water can reduce the levels below what causes damage! This is why it’s so important to get a high-quality water filter for your home.
Now, I don’t want to turn you away from tap water completely. It does have some benefits, like being free and available in many areas. In fact, it’s the most common source of public water due to its convenience and ease of maintenance by municipal water suppliers.
Still, you shouldn’t drink unfiltered tap water on a regular basis due to the presence of chlorine, fluoride, heavy metals, and other chemicals which are unhealthy for your body. Not only that— but it’s not always available in areas where you don’t have public water. So if you can afford to use a high-quality filter at home AND you live somewhere with polluted tap water , then you should definitely get one!
But what if you can’t afford a filter? Should you just give up and keep drinking polluted water? Of course not! You should do your best to find an affordable solution , such as using filters at home AND carrying bottled water with you. This is the approach I take, since I live in an area where the tap water is pure but the cost of good filters would be prohibitive.
But remember— if you can afford to use a filter, then it’s definitely the best choice. Not only will your body thank you, but you’ll save money in health costs down the road by avoiding harmful chemicals! Plus, they are surprisingly affordable nowadays… which is just one more reason to get one ASAP.
Filters that remove chlorine and chloramine
Chlorine is used in most municipal water supplies to ensure that pathogenic microorganisms do not enter the water supply. Most modern filters contain activated carbon, which can remove chlorine from drinking water.
Chloramine is used instead of chlorine by about half of all cities with public water systems because it has a longer shelf life and does not easily evaporate. Most carbon filters have not been tested for removal of chloramine, but some tests have shown that the most popular activated-carbon filter cartridges do remove chloramine.
One brand of “point-of-use” chlorine and chloramine filter is called the Berkey water filter. This type of filter does not need to be inserted onto the water supply line. The filter must be cleaned periodically, which can be difficult for filters that have not been tested for chloramine removal.
Filters that remove fluoride
A fluoride filter is a water purification system that helps reduce the amount of fluoride in drinking water. The filters are usually made from activated alumina or bone char, and can be installed on a private well or at a point-of-use within a building. Household filters may remove up to 95% of fluoride.
Fluoride filters do not remove other contaminants such as metals and pesticides, and may require maintenance. Some types of fluoride filters use activated alumina or bone char as adsorbent media to reduce the release of metal ions such as lead, mercury and arsenic from household plumbing materials. Bone char is particularly useful because it can also be used to remove arsenic from water.
Some studies show that tap water treated with fluoride filters may contain lower levels of certain contaminants, including cadmium, lead, and mercury compounds (but not fluoride itself). The effectiveness of these filters can vary depending on the influent water conditions like pH and total hardness.
Filters that remove heavy metals
For most people, the topic of heavy metals is not something they want to think about when relaxing. But when it comes to the quality of our water and food, we need to make sure that we are providing ourselves with safe sources. Heavy metals like lead and mercury can be present in our tap water and even in some fish!
Luckily for us, there are filters that can remove these heavy metals from our tap water and even the fish we eat!
The purpose of this system is to reduce or eliminate all lead, mercury, VOC’s (volatile organic chemicals) and other contaminants present in your tap water.
Other types of water filters
Those who are concerned about the fluoride, chlorine and other contaminants in their drinking water may wonder if there is a way to filter it properly. Here are some common types of water filters that may be able to help.
- Carbon filters, usually made from activated charcoal or coal, can remove organic compounds such as pesticides and herbicides as well as chlorine and its byproducts. Some carbon filters will even reduce heavy metals, fluoride or arsenic that may be in the water supply.
- Reverse osmosis filters are typically used to remove toxins from drinking water as well as salt from seawater. The process of reverse osmosis involves semi-permeable membranes with tiny holes, allowing only certain particles to pass through. To set up a system at home, water is poured into a reservoir and passes through the holes of the membrane. The contaminants are left behind on the other side while the filtered water comes out into another tank or storage container.
- Distillation devices boil water then condense the purified steam into drinking water. This is an effective technique for removing salts, heavy metals and minerals as well as fluoride and other contaminants.
- Ultraviolet (UV) water filters use ultraviolet light to kill any microbes that may be in the water supply. These filters do not remove all toxins but do make the water safe for drinking.
- Gravity-fed systems filter out contaminants by rerouting water through a purification component housed in another chamber. The two chambers are linked together and the contaminated water is poured into the top section, which has a filtration system inside of it. As gravity pulls the liquid through, chemicals, bacteria and viruses are eliminated before they have a chance to enter your body.
- Ionizing water filters use electricity to remove pollutants from the water by converting them into a form that will not be harmful to the body. These systems do not use chemicals or charcoal and can be useful for those with allergies or sensitive skin.
Boiling your water before drinking it is one of the best methods of purifying it, as long as you let it cool before using. It is not recommended to boil the water and then store it in a container for later use because bacteria can form while it sits.
This depends on what you’re looking for. A mechanical filter only removes contaminants which are smaller than the holes in its fabric; this means that they can clog and lose their effectiveness over time, and it also limits what types of chemicals they can remove.
Adsorption filters work by bonding themselves to the impurities in the water; this means that they will never fully be taken out of the water, but it also means that they should never lose their effectiveness.
On the other hand, adsorption filters work by a process which is not fully understood by modern science, and many scientists think that this means there’s no way to know if they’ll keep working forever. In general, I would recommend mechanical filtration for home use and adsorption for outdoor use where it can be replaced as needed.
This refers to the minimum size of a filter’s holes, and it is usually given in microns (μ). For example, if you want to use a cloth filter which has 100 μ absolute pore size, this means that nothing will be able to pass through the filter which is smaller than 100 μ. It does not mean that the filter can’t pass anything larger than 100 μ, but this should be kept in mind when choosing a filter.
The micron rating of a filter is given as an average, and it refers to how many contaminants of a certain size are still able to pass through the filter. If a filter has, on average, one micron size holes, then half of the contaminants that are 1 μ will be able to pass through the filter while the other half are blocked by it.
GAC stands for granular activated carbon; it’s one of the most common adsorption filters. GAC comes in a variety of forms, the most common being “powder” or “granular.”
GAC filters work by attracting and trapping chemicals using a process called adsorption. This means that atoms from the impurities bond to its surface creating a new compound. Once a contaminant has bonded, it cannot be released again without breaking the bond between it and the carbon.
GAC filters are usually only used to remove organic chemicals, such as pesticides or VOCs (volatile organic compounds). This is because they require a bonding process which is specific to organic compounds, and this means that inorganic chemicals cannot be removed by GAC filters.
A micron cartridge contains an absolute pore size of 1 μ; this means that the filter blocks any contaminant which is smaller than 1 μ. It can remove most viruses and bacteria, but not all; the only way to make sure is to test it using a coliform test or other appropriate methods.
Depth filters work by slowly forcing water through very tiny pores (usually less than 0.02 μ) which are so small that even most viruses can’t fit through. They remove bacteria, parasites, and all other contaminants which are smaller than 0.02 μ.
Reverse osmosis (RO) filters work by pushing water through very small tubes (usually less than 1 μ) which allow only pure water to be passed through. This means that RO filters remove all contaminants and impurities, including bacteria and viruses
Whole house systems use either micron or depth cartridge(s) which are usually integrated into the input line of a storage tank. This means that they will remove bacteria and parasites, but not viruses. For more thorough filtration, micron cartridges can be used; otherwise, depth filters are good for taste and smell.
If there is something that isn’t normally removed during the filtration process, then it is often possible to use a variety of filters or chemicals to remove it. This usually only needs to be done if impurity is present in incredibly large quantities.
Your water filter is one of the most important pieces of your home. It’s responsible for keeping you and your family safe from disease-causing contaminants, but there are a lot of different types on the market today.
What type should you choose? The answer depends on what kind of water source you have and how often it changes (or if it does at all). We explain some common filters below to help you make an informed decision about which will work best for your needs!
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