Types of Water Filters

Water filters come in a variety of forms from pitchers, refrigerator filters and faucet and under-the-sink models to whole-house systems that combine multiple types of filter media. It’s important to identify the contaminants you need filtered and then do comprehensive research to determine the best type of filter for you.


Reverse Osmosis

Using a partially permeable membrane to separate ions and unwanted molecules from water molecules, reverse osmosis systems remove some of the most dangerous contaminants from water. These include lead, asbestos and 82 other potentially harmful chemicals that can cause illness or even death. The resulting water is considered to be among the safest forms of drinking water, and it has even ended boil water advisories in some communities.

Water filtered through reverse osmosis is also more likely to be free of bacteria and other pathogens, which is why it’s so popular in many countries where water quality is less than ideal. It’s even used to produce pure water for industries like pharmaceuticals, boiler feed and metal finishing.

Since reverse osmosis systems use a lot of pressure to operate, they need a sediment pre-filter and carbon post-filter in advance of the membrane. These filters also help to prevent the membrane from fouling with bacterial growth, chlorine and iron. This is why they are often combined with water softeners. The salt rejection rate is an important metric to look for in reverse osmosis systems. The lower the amount of salt that passes through, the better the system is performing.


Sediment water filters work to remove large dirt particles from your home’s drinking water. This makes the water clearer and better tasting. These types of filters don’t have the ability to remove chemicals, heavy metals or bacteria.

Sediments are a natural part of aquatic ecosystems, but their quantity and characteristics can affect the physical and chemical integrity of waterways. Excessive sediment in streams can result in high turbidity, which obstructs sunlight and limits photosynthesis, reduces biologically available oxygen and increases water temperature. Sediment can also transport other pollutants, such as nutrients, metals, organic chemicals and pathogens, from land to water.

Different sediment filter models use different techniques to trap particulates. Some have large surface areas to catch huge volumes of debris, while others use depth filtration. These push the water through walls of filter media that grow tighter as it moves toward the center, catching more and more smaller debris particles. These filters are usually rated by their micron rating, which tells you what size of particle they can catch. This information can help you find the right one for your home.

Chemical Compatibility

Water filters help remove chemical impurities from drinking water which can affect its taste and odor. They are also able to prevent the formation of limescale in pipes and fixtures. The filter works by absorbing the chemicals through the use of carbon granules. Activated carbon is jam-packed with nooks and crannies that can trap impurities. Common types of carbon used in the filter are coconut shell, wood-based and bituminous coal.

The best way to find a water filter that is chemically compatible with your liquids is by reading the chemicals’ Safety Data Sheet (SDS). The chart will list the chemicals and component material options and will provide their compatibility rating.

Chemical compatibility is a measure of the stability of two substances when mixed with each other. When a mixture does not undergo any chemical reaction with each other, it is considered compatible. On the other hand, if the chemicals do react with each other, it is considered incompatible. Incompatible chemicals can lead to mechanical weakening or evolution of gas which are both dangerous. A good water filter should be resistant to a wide range of chemicals in order to meet the requirements of your application.

Micron Rating

The micron rating of a water filter determines its ability to trap tiny particles and prevent them from reaching your drink. Filters with smaller micron ratings are more effective at removing harmful contaminants that can cause health issues or affect the taste and odor of your water.

One-micron filters, for example, can eliminate most bacteria and parasites like E coli, Salmonella typhimurium and Shigella dysenteriae. They also reduce chlorine, organic chemicals and lead. Their pore structure allows for higher flow rates but still offers adequate protection against the harmful impurities present in most public drinking supplies today.

Filters with micron ratings of 50 microns and above are ideal for a wide range of applications. They provide the perfect bridge between the much more specialized and expensive ultra-fine filters and are capable of trapping large quantities of impurities without clogging easily. They are a great choice for businesses that require a high level of purity. They are commonly used in industries such as oil and chemical facilities. They are available in a variety of sizes including wound string, spun and melt-blown cartridges.


The size of a filter is a major consideration for most homeowners. The larger a filter is, the more it can hold and the higher the instantaneous flow rate it can handle. A large filter also ensures that water will not be restricted at access points in the home.

Filter sizes are measured in microns. One micron is 1/1000 of a millimeter. Beach sand is around 60 microns, human hair is 150 microns, and ground coffee has an even smaller measurement of 100 microns.

A filter that is too small will be quickly clogged, restricting the flow of water to the rest of your home’s plumbing system. To avoid this, it is essential that you find a filter that has the appropriate capacity for your household. Taking into account the number of bathrooms and the household’s peak water consumption needs is a good place to start. It is also important to note that filters can have different port sizes, which will impact gallons per minute and water pressure. The larger the port size, the better.