Best Water Filtration System for Home

What exactly are we trying to filter out?

virus art / Elena mozhvilo / unsplash

The first step in choosing the right filtration system is to understand what exactly it is we’re trying to filter out. There are four classifications of contaminants according to the CDC and EPA.

They are physical, chemical, biological, and radiological contaminants.

Physical contaminants

Physical contaminants refer to sediment, silt, or any type of debris that may be naturally present in the water supply. These contaminants are primarily found in groundwater due to the layers of rock that must be drilled through. Surface water such as lakes and rivers may also have a high concentration of sediment and silt.

While large physical contaminants can be harmful if consumed, they’re more of a concern for the water system as they can cause blockage and damage to water pumps and filters.

Physical contaminants must be “blocked” before entering the drinking water supply and this is typically done through a pre-filtering process.

Chemical contaminants

Chemical contaminants are usually the most common type of contaminant due to their broad category and refer to anything of an elemental or chemical make-up. These can be as simple as an element on the periodic table such as chlorine, nitrogen, arsenic, and fluoride, or as complex as herbicides, pesticides, VOCs, and pharmaceuticals. Chemical contaminants can also refer to heavy metals such as lead and mercury.

These types of chemicals can cause long-term sickness if consumed. Arsenic is known for causing cancer and skin lesions while lead and mercury can cause neurological and developmental problems (WHO).

Chemicals are best removed from the water supply through the adsorption of a high-affinity medium such as activated carbon. Because chemicals vary in molecular size, several layers of filtration are often required for completely removing the entirety of harmful components.

There are some elements that are naturally present in water and aren’t necessarily harmful if consumed. Elements such as calcium and magnesium, quite common in groundwater and lakes, are actually beneficial for human consumption. However, high concentrations of these elements can be damaging to the plumbing system. We’ll get into how water softening can help remedy this, later.

Biological contaminants

Biological contaminants are perhaps the most concerning of all contaminants as the consequences of consumption are most dire. These refer to bacteria, viruses, and parasites that may be present in the water, and the conditions that arise from them are known as waterborne diseases.

Biological contaminants are most common in stagnant water sources, water sources exposed to human or animal feces, and countries with poor water treatment services.

Bacteria - The most common biological contaminants include Typhoid, Cholera, E. coli, Salmonella, and Legionella. While symptoms among these diseases vary, untreated conditions can lead to death.

Viruses - The most common viral disease found in water is the Norovirus, also known as Traveler’s Disease, and is typically transmitted when someone drinks from a foreign water source.

Protozoa - Finally, parasites such as Giardia and Cryptosporidium are commonly ingested when drinking from a water source where infected animals have defecated.

While carbon filtration can block some of the larger bacterial entities, viruses are usually small enough to pass through the filter block.

Chemical disinfection through chlorine or iodine can kill bacteria and viruses in varying time frames. Parasites can be killed in a much longer time span.

Boiling water is also an effective method for killing biological contaminants, though also isn’t the quickest of methods.

The most effective method for eliminating all biological contaminants is through ultraviolet radiation. UV purification almost instantly renders all bacteria, viruses, and parasites completely harmless, making contaminated water safe to drink.

Read our guide on UV purification for home use to learn more.

Radiological contaminants

The least common of contaminants are radiological or radioactive contaminants. These refer to unstable elements such as plutonium and uranium that may have been emitted due to nuclear radiation. While rare enough to not bear much weight when deciding on which filter to purchase for your home, it is worth recognizing nonetheless.

The most effective method for removing radiological contaminants is a combination of carbon filtration and reverse osmosis (Forbes).

Where does your water come from?

kitchen faucet / pxhere

How and where your water is sourced has a significant effect on the potential contaminants you may come into contact with, which then affects the type of filtration process you should use. Here's we'll cover the most common sources for residential water.

Municipal water services

Most municipal water sources in the United States come from either groundwater via a large well or surface water via a dam or reservoir. These public water sources are treated by the city via a process of flocculation, sedimentation, filtration, and disinfection (CDC).

Flocculation and sedimentation remove all physical contaminants such as debris, silt, and sand.

The filtration process involves layers of carbon for removing MOST, not ALL, of the dangerous chemical contaminants in the water.

The disinfection process then kills all biological contaminants that may be present.

It is important to note that while public water treatment does remove most of the harmful contaminants, the filtration process for chemical contaminants is very basic. It is recommended that households still perform their own filtration process to further remove chemical contaminants that may have slipped through the initial carbon filter.

Heavy metals such as lead and other chemical compounds such as herbicides and pharmaceutical drugs can still be found in tap water.

Private wells and community wells

Groundwater is an excellent water source due to it being naturally filtered by the earth’s crust. While biological contaminants aren’t as common in groundwater as it is in surface water, physical contaminants such as sediment and rock will certainly need to be pre-filtered out. A high concentration of naturally occurring chemical elements such as magnesium, calcium, and iron may also be present (USGS).

Those who rely on a private or community well should have a sediment pre-filter for physical contaminants and possibly a UV filter for any potential biological contaminants. To remedy the high concentration of hard water and iron, a water softener, water condition, or iron filter may be needed.

Read our guide on well water pumping to learn more.

Rainwater

Rainwater harvesting can be a very useful means for supplementing a household’s existing water supply. While typically used for outdoor gardening purposes, it is possible to filter rainwater for drinking.

Rainwater, typically caught by a large catchment system such as a roof, can contain physical and biological contaminants. Debris such as twigs and dirt as well as animal feces and algae are often present in rainwater and therefore must be filtered out.

Many rainwater filtration systems consist of a UV filter and activated carbon combination.

Learn how to filter rainwater from our guide.

Surface water

Some off-grid cabins source their water from a lake or river via a water pump. Surface water often contains physical, biological, and chemical contaminants and therefore must be treated for such. In most cases, a reverse osmosis system will treat surface water for all of its harmful contaminants, making it safe to drink.

Now that we've covered the different sources for water and the possible contaminants present in each, let's get into the best types of filtration for each scenario.