The best water filters for your home

We have compared and analyzed a dozen websites – from Amazon to Wirecutter – for their recommendations and ratings for home water filters and compiled the results into this guide for you.

Consumers have a choice of many different types of filters. Determining which type is most appropriate for you—or whether you need a filter at all—depends on what functions you want a filter to provide. You might want to test the quality of your water first with one of the many available water quality testing kits. It is important to understand that no filter eliminates all contaminants, so understanding what filters do and don’t do is important.

Based on use, the recommendations are grouped into four categories: The best water filter pitchers and countertop dispensers, the best faucet-mounted water filters, the best under-sink water filters, and the best reverse osmosis filters.

But let’s start with the water filter basics first: why and how.

Contaminants that can be found in tap water can include microorganisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the water unfit to drink.

Different water filters have different functions. Some can make your water taste better, while others can filter out harmful chemicals or germs. No single filter can keep every type of contaminant out of your drinking water, and not everyone needs a water filter if they have access to high-quality tap water.

Another important consideration is that tap water contains small quantities of beneficial substances as well, such as fluoride, which helps prevent tooth decay; or the appropriate amount of a disinfectant, like chlorine, that helps keep your water safe from germs. On the other hand, some substances that might be in water can be harmful, such as lead and the parasites (germs) Giardia and Cryptosporidium. Filters can remove both good and bad substances from your water. Depending on your circumstances, filtering your water might not be a good idea.

NSF International is an independent organization that develops public health standards for products. One way to figure out what a water filter does is to look for an NSF certification on the label. You can look up specific products in the NSF online database to see what they are certified to protect against. Some of the NSF standards applicable to water treatments are standard 41 (taste and odor), 53 (cyst reduction), 58 (reverse osmosis), and 62 (distillation).

Relevant for us with regard to household water filters are three types of water filtration: mechanical, adsorption, and reverse osmosis.

Mechanical microporous filtration physically removes sediment, dirt or any particles in the water using a barrier. The degree of effectiveness depends on the pore size of the filtration membrane – the smaller the pores the more particles get filtered out. Pores with a 5-micron size remove most particles visible to the naked eye. One tenth of the size, 0.5 micron, removes parasites like Giardia and Cryptosporidium.

Adsorption filtration uses a physical process in which small particles in water are attracted and become attached to the surface of something larger (the adsorbent). Throughout history, people have used carbon (charcoal) as an effective adsorbent for water treatment.

In most household water filters an improved form of carbon, called activated carbon, is the adsorbent most commonly used to attract and hold dissolved contaminants. These filters perform pretty well in removing chlorine, particles such as sediment, volatile organic compounds, taste and odor. However, they do not remove arsenic and heavy metals, fluoride, bacteria or pharmaceutical compounds.

Reverse osmosis, unlike physical and chemical filtration, uses pressure to push water through a semipermeable membrane layer. This membrane has pores small enough to trap contaminants but big enough to allow water to pass through.

A multi-stage reverse osmosis water filtration system will remove all of the above-listed contaminants and many more. While countertop filters can only remove impurities down to one micron in size, reverse osmosis systems will filter out contaminants down to .0001 microns to effectively remove up to 99% of all contaminants in the water including arsenic, fluoride, heavy metals and pharmaceutical drugs. Reverse osmosis systems remove the widest spectrum of contaminants compared to other types of filters available.

Reverse osmosis is a highly effective way of purifying water and is usually combined with a number of other filters such as a mechanical (sediment) filter and an absorption (activated carbon) filter in order to return water with few contaminants remaining.

The best faucet-mounted water filters can eliminate more contaminants than pitcher filters do and give you filtered water from the sink on demand. Because they usually are larger than pitcher filters, they last longer between replacements.

Anyone who goes through more than a couple of gallons of drinking water a day will probably be happiest with an under-sink filtration system.