You’re considering getting a water filter but how do you find the right one?
We've created this little water filter guide to help you understand the technologies available.
Also read our Best Water Filter article for the Top 8 water filters including jugs, faucet filters, under-the-sink filters, wholehouse filters and water bottles.
The first question you should ask is what problem you want to solve?
To chose a water filter you first need to understand what your needs are in terms of drinking water.
Typical reasons that people need a water filter include
- Tap water is drinkable (potable) but tastes and smells poorly
- Concerned about or risk of lead contamination
- Worried about specific contaminants such as microplastics, nitrates, chlorine by-products, etc in your water
- The tap water is not drinkable and needs to be treated due to risk of e.g. bacteria (Legionella, E.coli, etc) or viruses (enteroviruses)?
- Preference for distilled tap water removing all contaminants and minerals
Generally public tap water in Europe and North America is safe to drink unless your local water provider tells you otherwise. However, this doesn't mean that it's clean or healthy. Contaminants can leach from the pipes or local water tanks. There can also be issues with unregulated contaminants such as microplastics.
Once you know what the problem you want to solve is then the tables below may help you chose the right kind of filter.
Water filters available based depending on budget, preference, convenience and ease of installation/use:
- Water jugs – just fill it up with water and it filters it for instant use or place in the fridge to keep cool. E.g. Soma, PitcherPro by TAPP Water and Brita
- Faucet filters – installs directly on your faucet and usually have a switch to turn filtering on and off. E.g. Tapp Water, Culligan and PUR.
- Counter top filters – connects to your faucet or standalone to be filled and filters the water for drinking. E.g. Berkey and Propur
- Under the counter filtration – filters the water specifically for the kitchen with replacement cycles typically every 3 to 12 months. E.g. Culligan and 3M
- Whole house water filtration system – filters all incoming water in house for kitchen faucets, appliances, bathroom and shower. E.g. PureEffects, 3M, GE, Aquasana
- Shower filters – covered in a separate section on this website
Within each of these types there are different technologies used and here’s a summary table with how each one works.
Drinking water filter guide overview and what they remove:
|Carafe in the fridge
|To simply get rid of the chlorine the simplest method is to leave a carafe of unfiltered water in the fridge over night. Generally most of the chlorine evaporates in 12-24 hours.
|About 80-90% of the chlorine evaporates.
However, it doesn't remove any contaminants or chlorine by-products that might be bad for your health.
|Granular activated carbon (GAC) or Carbon Blocks are made from raw organic materials (such as coconut shells or coal) that are high in carbon. Carbon is the most absorbent material known, and it is uniquely efficient because of thousands of tiny pores that can absorb. Some also use secondary media such as silver to prevent bacteria growth.
|Active carbon filters are most effective at removing chlorine, sediment, volatile organic compounds (VOCs), taste and odor from water. Remove most bacteria. High quality carbon blocks can also remove microplastics, lead, nitrates and many other contaminants.
|Reverse Osmosis (RO)
|Commonly referred to as RO, is a process where you demineralize or deionize water by pushing it under pressure through a semi-permeable Reverse Osmosis Membrane. RO filters are usually combined with an active carbon filter to trap organic chemicals and chlorine or CTA (cellulose tri-acetate) membrane prior to the RO membrane.
|Capable* of removing 99%+ of the dissolved salts (ions), particles, colloids, organics, bacteria and pyrogens from the feed water (RO system should not be relied upon to remove 100% of bacteria and viruses).
* Note: Capable = industrial grade RO systems
|UV Water Purification systems use special lamps that emit UV light of a particular wavelength that have the ability, based on their length, to disrupt the DNA of micro-organisms. As water passes through a UV water treatment system, living organisms in water are exposed to UV light which attacks the genetic code of the microorganism and rearranges the DNA /RNA, eliminating the microorganism’s ability to function and reproduce.
Normally UV filters are combined with another filter such as active carbon.
|Remove 99.99 percent of bacteria and viruses that may be present in your tap water. See below for longer list.
|A home based system is very similar to those used in municipalities except on a far smaller scale. They are systems that include a recirculation pump, an ozone generator, a water recycling tank, and an ozone line vent. Ozone drinking water purifiers are generally located at the water intake point for the home between the intake and the storage tank. Ozone also uses UV light but in this case to create unstable oxygen molecules.
Ozone is often combined with activated carbon filtration to achieve a more complete water treatment.
|Ozone has been found to effectively remove 99 percent of all biological pathogens including Giardia and Cryptosporidium. It also is effective at removing iron and manganese as well as freeing up chlorine to kill even more microbes if used in a multiple step system.
|The ion exchange process percolates water through bead-like spherical resin materials (ion-exchange resins). Ions in the water are exchanged for other ions fixed to the beads. The two most common ion-exchange methods are softening and deionization. Deionization is generally used in combination with active carbon filters. Softening is primarily used before RO filters.
|Primary use is to soften the water and to reduce contaminants. Generally used in combination with a active carbon or a RO filter. Also frequently marketed as making the water alkaline (pH level above 7) and thus healthier for the body.
|Water is first heated to boiling. Then the water vapor rises to a condenser where cooling water lowers the temperature so the vapor is condensed, collected and stored. Most contaminants stay behind in the liquid phase vessel.
|Removes most contaminants. Destillation is mostly used in industrial processes.
|Not really a filter system but as it’s used by many people as a last resort it’s included.
Removes bacteria and viruses
Note that nothing else is removed.
Pros and cons of each of the filter technologies?
Keep reading our water filter guide:
|Easy to install and replace filters (with the faucet and carafe models)Sufficient for most common water issues in developed countries
No waste of water
Leaves minerals and salt in the water
Cost as little as €60 per year (e.g. Tapp Water)
Doesn’t remove all contaminants such as bacteria and viruses (they can if combined with ultrafiltration).
Doesn’t reduce hardness or remove calcium (resulting in limescale)*
* Note: Active carbon filters with Ion Exchange or other limescale inhibitors may also remove calcium/limescale
|Reverse Osmosis (RO)
Output is very clean water and can be used to make undrinkable water potable (drinkable)
Filter replacement approximately every 2-12 months (differs by brand and utilization)
Waste as much as 6x the water output
Removes all desirable minerals from the water
RO has a hard time removing or reducing calcium and magnesium – the minerals that make water hard so may require water softening before
Expensive and difficult to install and maintain versus jug and faucet filters (requires a professional)
Very effective in removing bacteria and viruses
Reliable and cost efficient – only lamp & sleeve replaced annually
Clean – no dirty parts to dispose of
Cannot be used on it’s own in most cases
Does not remove any other contaminants from water such as heavy metals, salts, chlorine or man-made substances like petroleum products or pharmaceuticals.
UV light is only able to work if water is clear. If the water is murky or contains “floaties,” a pre-filter should be used
Primarily a disinfectant that effectively kills biological contaminants.
Oxidizes and precipitates iron, sulfur, and manganese so they can be filtered out.
Will oxidize and break down many organic chemicals including many that cause odor and taste problems.
More expensive than the other technologies
Unstable oxygen (i.e., ozone) acts as an oxidant in the body and may contribute to cellular damage, aging, diseases, etc.
Removal of >98% contaminants
No wasted water
No electricity needed
Fast flow rate
Ideal for whole house filters
Does not effectively remove particles, pyrogens or bacteria
High operating cost over time
There is no scientific proof that alkaline water is better for the health
Removes a broad range of contaminants
Consumes large amounts of energy
System usually takes a large space on counter
Does not contain any minerals or salt afterwards
May not remove pesticides and herbicides
Doesn’t require any equipment
Vastly reduces risk of getting ill from short term consumption of water
Does not remove a lot of contaminants like metals
Very expensive and time consuming method for high volumes of water
So which filter should you choose?
Active carbon faucet filter, a water filter jug, under-the-sink filter, destillation, UV, RO or no filter at all?
Hopefully the water filter guide overview above helped answer your question.
Also read about how water filters work.
Unless your water report indicates specific issues with your water or if you have other concerns such as pH level, arsenic or specific bacteria/viruses then TAPP Water filters will generally meet your needs.
WHO, EPA, EU, Water Institute of Barcelona, Water institute of Granada, Water University in Stockholm, Water Benefits & Health and more.