What Does A Water Filter Do?

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The National Health Service (NHS) in Britain recommends drinking “6 to 8 cups or glasses [of water] a day” (1.5 to 2.5 liters or 0.3 to 0.6 gals). However, the exact amount of water required by any given person will vary depending on their specific circumstances.  As a result, there has been a rise in the sales of water filters designed to rid the water of any potentially dangerous contaminants. But what does a water filter do, and are they necessary? 

Since water is essential to survival, it’s no surprise that most of us enjoy drinking water that meets our high standards for cleanliness and flavor. Come on, let’s have a better look at how water filters provide clean water to their users.

What Does A Water Filter Do?

Filters improve the quality of water by getting rid of contaminants such as silt, bad taste and odors, hardness, and germs. There is a wide variety of filters and cartridges to address every issue involving water. From improving the taste of drinking water to more specialized uses like brewing coffee and creating crystal-clear ice you can use filtered water.

Types Of Water Filters And How Do They Function?

There are five distinct kinds of water filtration systems available, each optimized for a certain use case, i.e. what you’re attempting to filter out or prevent. 

  1. Mechanical Water Filters
  2. Sequestration Filters
  3. Reverse Osmosis Filters 
  4. Absorption Filters
  5. Ion Exchange Filters 
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Mechanical Water Filters 

Mechanical Water Filters

Mechanical filtration relies on a barrier to physically strain out contaminants such as silt, grit, and other particles from the water. A mechanical filter may be anything like: 

  • A simple mesh designed to catch and retain big particles 
  • A ceramic filter with a highly sophisticated pore structure designed to catch even the tiniest of harmful organisms.

To quantify how successful a filter is in removing particles of a certain size, a micron rating is typically assigned to filters that employ mechanical filtration. 

Standardized evaluations of mechanical filtration

5 micronRemoves most particles observable through the naked eye
1 micronRemove particles that are too little to notice without a microscope
0.5 micronRemoves cysts like giardia & cryptosporidium

Sequestration water filters

Sequestration water filters

Chemical isolation, or “sequestration,” is the process by which anything is kept in its safe environment. To prevent limescale and corrosion in water purification systems, food-grade polyphosphate is often utilized. However, polyphosphate is rarely used in large doses and does not eliminate scale; rather, it merely slows its growth. Therefore, polyphosphate does not soften water, but rather keeps the minerals in solution to avoid scale buildup on surfaces.

Scale inhibition is not a perfect solution because some hard minerals may still be present in the water. Water softening via ion exchange is typically advised:

  •  In places with alkalinity levels of 180 ppm or higher (extremely hard water).
  • In applications where water is kept at a constant temperature of 95°C or more.

Reverse Osmosis water filters

Reverse Osmosis water filters

By pressurizing water across a semipermeable membrane, reverse osmosis (RO) removes dissolved inorganic particles (such as magnesium and calcium ions) while allowing the water to pass through.

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To return water with few impurities still present, reverse osmosis is used with several different filters. It includes a mechanical (sediment) filter and an absorption (activated carbon) filter.

Water pressure is used to push the water through the membrane in a reverse osmosis system, negating the need for electricity, waste water is still generated and must be drained. In solutions where 99.9% pure water is needed, RO offers the finest level of filtration available. Even though the extra filters participating in multi-stage water filtration can make a reverse osmosis unit more costly than other filtration methods.

Absorption water filters: what does a water filter do

Absorption water filters

Carbon is often used in water filters because of its high absorption capacity and its ability to effectively remove pollutants from water. Carbon’s prodigious interior surface is crammed with pits and crannies that may trap chemical pollutants like chlorine, making it a very efficient adsorbent.

Granular activated carbon (GAC) is a prominent ingredient in household filters because of its ability to absorb bad odors and flavors. Carbon block components, found in more pricey filters, are typically more effective at removing particles and typically come with a micron rating.

Good to know: what does a water filter do?

Carbon filters can be made from many various materials, such as wood or coconut shells, with the latter being more expensive but also more effective.

Ion exchange water filters

Ion exchange water filter

By replacing the magnesium and calcium ions present in hard water with other ions including sodium or hydrogen ions, ion exchange can be utilized to soften the water. Ion exchange is preferable to scale inhibition because it physically eliminates the hard minerals. Therefore lowering limescale and making the water appropriate for situations where it is kept at a continuously high temperature, such as commercial coffee machines.

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A popular method of ion exchange employs a bead-like substance called an ion exchange resin. Some Water Softeners employ a resin very similar to that used in air purifiers. Except that the sodium ions required by the resin in the water softener need to be refilled regularly to keep the resin from becoming ineffective. 

Because the regulatory limit for salt (sodium) in drinking water is 200 milligrams/liter, resins that employ sodium ions are not typically used in drinking water filters. Hydrogen-based ion exchange resin is ideal for filters because sodium ion exchange raises salt concentrations.

Final words: what does a water filter do

Final Words 

As you can see, many filtration methods are effective at getting rid of specific toxins, but there is yet no foolproof method for purifying water of all known hazards. Therefore, many residential water filtration systems employ a combination of two or more of these techniques. Be cautious when shopping for a water filter for your home. Remember that it’s unlikely that you’ll be able to get rid of everything bad. Another thing to keep in mind is that most water filters have some sort of recurring expense, and if you don’t maintain them, they can make your water quality worse.

I hope that now you know what does a water filter do and how effective it is.

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