Water filters come in different types and shapes. The filtration capabilities, flow rate, ease of installation & maintenance, and cost vary according to the type and shape.
In this article, we will discuss different water filter types. This guide will help you understand how a water filter works and which one is best for you.
Water Filters – Different Types & How They Work?
Just a Pro Tip: Private well owners must test their water before buying a water filter. Most homeowners install a combination of water filters/softeners to make their water fit for drinking and everyday use. City water users can ask local authorities for a water quality report or access it from EPA’s website.
Water Filter Types based on Filtration Technique
Water filters are divided into the following categories based on the filtration technique/principle.
- Mechanical (Sediment)
- Adsorption (Carbon)
- Ion Exchange
- Reverse Osmosis
Mechanical (Sediment) Filters
Mechanical filtration refers to filtering sediments in the water. These filters use a mesh screen to remove suspended particles. Sediment filters have a micron rating that defines their working capabilities.
Mechanical filters with a big micron rating (above 50) remove large suspended particles in water. They are often installed before other water filtration systems.
Mechanical filters with a small micron rating can filter dissolved solids. They usually have a micron rating below 5 microns. However, these filters cannot remove microorganisms in water.
Mechanical filters have a long life compared to other filters. Depending on water quality and usage, they can last for 2-3 years. Most mechanical filters can be washed and reused.
Mechanical filters have different price ranges. You can find one as low as $30; high-end models may go up to $500. The mesh size and filter life are often the price deciding factors.
Adsorption (Carbon) Filters
Carbon filters work by adsorbing contaminants. Carbon filters catch contaminants because of a big internal surface with pores and nooks that trap contaminants.
Carbon filters are found in almost all types of home filters because of their capability to remove common water contaminants like chlorine, VOCs, and organic compounds. Activated carbon filters can also remove lead and other heavy metals. A few carbon-based filters can also remove fluoride from drinking water.
Adsorption filters are common because most contaminants are carbon-based. These filters hold these contaminants, which is why they need replacement after a fixed time. Most carbon-based filters have a 4-6 months life but vary based on water quality and usage.
The price range for carbon filters varies on filtration capacity and which contaminants they can filter. A simple carbon filter (pitcher filters) may come as low as 20 dollars, whereas activated carbon filters may cost as high as $700.
KDF (Kinetic Degradation Fluxion) filters are made of copper-zinc granules that remove lead, iron, manganese, and sulfide from well water. They are usually used with well water, but city water users can also install them if they have iron in the water.
KDF filters cause a chemical reaction that converts the structure of dissolved iron and other contaminants. The filter screen retains the insoluble matter and allows water to pass through. This is why you must change the KDF cartridge after a fixed time. The average age of a KDF filter is 4-6 months, while real-time life depends on water quality and usage.
KDF filters can remove up to 3-6 PPM iron, manganese, and sulfur from water. KDF filters are often found as a part of whole house water filters. Some manufacturers also make standalone KDF filters, but they must be used with a sediment filter to remove suspended particles.
KDF filters usually cost between $200-400. These filters offer a good value for money and can deliver a flow rate up to 15 GPM. They are suitable for small to medium-sized homes with 4-5 inhabitants.
Ion Exchange Filters
Ion exchange filtration happens when a dissolved contaminant in water is replaced with another element. Ion exchange filtration is usually used for removing calcium and magnesium. These minerals make water hard and are responsible for scales and stains on your appliances, plumbing fixtures, toilets, bathtubs, and showerheads.
Some ion-exchange filters also remove iron from the water up to a limited concentration (6-8 PPM). Ion exchange filters are commonly known as salt-based water softeners and rely on softening salt, regeneration and backwash for effective working.
Ion-exchange filters change water’s chemical properties. The sodium level in water slightly increases after passing through a water softener. This is nothing to worry about unless you are on a sodium-free diet.
These filters require periodic salt replacement. The resin bed in the unit is backwashed periodically to replenish the salt media. These systems are usually installed for well water and can provide a flow rate of up to 20 gallons per minute.
A typical water softener costs $600-$1000. Water softeners are usually sold as a standalone unit, but many manufacturers also integrate them as a part of whole-house filters. The average life of a water softener is 15-20 years.
Crystallization is another treatment option to change how water interacts with other surfaces. A salt-free water softener or water conditioner works on the principle of crystallization. It doesn’t add or remove anything in water but alters the way water behaves.
The common techniques used for water crystallization include electrically induced precipitation, template-assisted crystallization, and magnetic water treatment.
Water conditioners are easy to install and don’t require salt or brine discharge. Many homeowners install water conditioners for specific appliances like water heaters, washing machines, kettles, and dishwashers.
Water conditioners come as standalone or as a part of whole house water filters. The cost varies from $100-400 for a standard water conditioner.
Reverse Osmosis Filters
Reverse osmosis filtration is exclusively used for drinking and cooking purposes. RO refers to a semipermeable membrane that is so small that it hardly allows water molecules to pass through. It removes soluble contaminants in water like TDS, cysts, mercury, arsenic, and lead. However, it can’t remove microorganisms from water.
A typical RO filter has a micron rating of 0.0001 microns. This is why RO units take time to filter water. A water tank is used with a RO membrane to collect filtered water. The typical flow rate of an RO filter is 0.5-1 gallon per minute, which is suitable for drinking water.
RO filters waste 1-3 gallons of water for every gallon of water filtered. This water is used to wash the RO membrane that holds the contaminants.
RO filters are available in standalone models or as a part of under sink water filters. A sediment filter is usually installed before a RO filter to protect it from big suspended particles in water and ensure effective performance.
Water is pushed into an RO filter by harnessing water pressure or using an electric pump. RO membrane usually lasts for 9-12 months, depending on water quality and your consumption.
You can find a standalone filter for as low as $150. RO filters that are part of multi-stage water filters can cost as high as $1000 because of the inclusion of carbon filters, KDF filters, remineralization stage, and UV filters.
Oxidation filtration is the process of precipitating iron and manganese in well water using an air stream. The oxygen in air changes soluble iron and manganese to insoluble precipitates, to be washed away or removed by a filter. The filtration media is replaced after some time. Oxidation filters come as standalone and as a part of multi-stage filtration systems.
The price of a typical oxidation filter is above $500. Oxidation filters can remove up to 15 PPM of iron & manganese from water. They can last up to 15 years with periodic maintenance.
UV filtration refers to using ultraviolet rays to treat water. Water is exposed to UV rays that change the genetic code of microorganisms like bacteria, viruses, protozoa, and cysts. UV filters don’t remove anything from water, unlike other filters. It makes microorganisms safe by eliminating their ability to reproduce.
UV filters come as standalone units or as a part of multi-stage filters. You’ll often find them along RO filters and whole house filters for well water.
UV purifiers or filters are repeatedly used in areas with bacterial contamination. The benefits include no water wasting, continuous water supply, instant purification, and easy maintenance and installation. The downsides are no filtration without electricity and no warranty on UV bulbs.
UV filters start upward of $200. Multi-stage filters with UV filter cost $500 to $1500. However, they offer good value for money as they make your water better than bottled water.
Chlorination is the process of disinfecting water using household bleach. It achieves the same result as UV filtration but in a different way. Bleach is poured into your well in a process called shock chlorination, or a chlorinator is used to add chlorine to incoming water.
Shock chlorination is a cheap and effective but labor-intensive method. It usually takes a couple of days to use your well water again after chlorination. Moreover, it also wastes a lot of water. A chlorinator is an electric device that adds chlorine to your water according to the volume of water that flows through it.
You can find chlorinator as low as $200, but some high-end models can go up to $2000. The biggest disadvantage of using chlorine to treat water is that it adds a chlorine smell and taste to water that must be removed with a carbon filter.
Water Filter Types based on Purpose
Point of Entry Systems
Points of entry systems filter water at the point where it enters your home. These systems include sediment filters, water softeners, oxidation filters, and large RO filters for community houses. Private well owners usually install sediment filters, water softeners, or oxidation filters as the point of entry systems. These are commonly known as whole house water filters.
Point of Use Systems
Point-of-use systems are installed at water pipes or faucets. They are also known as inline filters for refrigerators or appliances. Common examples of point-of-use systems are faucet water filters, shower filters, toilet filters, and refrigerator filters.
Under Sink Systems
Under sink systems are also known as point-of-use filters, but their popularity has earned them a category of their own. Under sink water filters are installed under your sink in the kitchen cabinet. An under sink filter can be a RO filter, cartridge filter, or sediment filter.
Pitcher Water Filters
These filters are used to purify drinking water. You pour tap water into the pitcher, and it filters the water in a few minutes. A common pitcher filter can remove lead, TDS, chlorine taste & smell, VOCs, and other contaminants depending on the cartridge installed. A typical pitcher filter has a capacity of 5-20 cups.
The Best Setup for Your Home: POE + POU Systems
Many private well owners are worried about maintaining safe water quality. It’s an easy task if you know how to do it. The first step is to get your water tested. The second is installing a POE filter according to the contaminants identified in the report. The third is installing a POU system for drinking water based on contaminants. The fourth step is to test water after installing the filters to see the performance.
Water testing is critical before buying a water filter because you can’t guess what’s in your water unless you get it analyzed. For example, you may think that your water doesn’t have bacteria, and you may not opt for a UV filter.
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