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Tap water filtration: the “what” and “how” of water filters for home

What is filtration?

According to the Cambridge Dictionary, filtration is “the act of passing a liquid or gas through a piece of equipment in order to remove solid pieces or other substances”.

When it comes to water, filtration refers to “the process of removing or reducing the concentration of particulate matter, including suspended particles, parasites, bacteria, algae, viruses, and fungi, as well as other undesirable chemical and biological contaminants from contaminated water to produce safe and clean water for a specific purpose, such as drinking, medical, and pharmaceutical applications.” (1)

Why do we filter water?

In ideal circumstances, source water doesn’t need to be filtered: nature can filter out harmful particles from water by absorbing rainwater into the soil, which takes out all impurities through various processes (for example, by physically removing large sediments, or by breaking down, adsorbing, or sequestering various substances), before it joins larger bodies of water, like lakes and oceans.

However, when either too many pollutants are released into nature or too much water flows to small areas at the same time (for example, after heavy rainfall in cities, with cement leading all water to drain systems), these natural processes lose efficacy, and source water can no longer be trusted to be safe to consume. This is when filtration becomes necessary.

In modern times, many countries have water filtration plants which treat source water before distributing it to households, to guarantee its cleanliness. But there are still many places in the world in which these systems are either not in place or not trustworthy. Additionally, even when the water is properly filtered, the pipes leading the water from filtering plants to homes are sometimes old, and the water can get re-contaminated after being cleaned. Lastly, many countries add substances to the clean water to ensure there is no organic growth after the water is cleaned (for example, chlorine) and these substances are not healthy to drink in large quantities. This is why many people use water filters at home.

What are the most common home filtration systems and how do they work? (2)(3)(4)

There are several different types of filtration systems available for home use. They work by applying different cleaning mechanisms, each able to filter out different types of pollutants with varying levels of efficacy. Some of the most commonly use filtration mechanisms are:

Mechanical filters: particles are physically removed from water by using a barrier, with holes small enough to prevent certain particles from going through. The smaller the pores, the larger number of particles retained by the filter. Examples of the most common mechanical filters are sediment filters (1 micron pores; will filter anything visible to the naked eye, like clay, sand and rust), ceramic filters (0.1 micron pores; can remove several organic particles, but not smaller ones, like viruses) and nano filters (0.001 micron pores; will remove most organic and non-organic matter, but not dissolved solids, which can affect the taste of the water).

Adsorption filters: when water passes through these filters, they attract and adsorb a range of particles (e.g.: chlorination byproducts, lead, certain pesticides); they do not however work with particles such as viruses and bacteria. The most common adsorption filters are known as activated carbon or charcoal filters, usually created with organic materials with a high carbon content (like wood, coal or coconut shells). Due to its low cost and simplicity, these filters are both available as tap water filters (i.e.: attached directly to the water pipes system) or as standalone solutions (e.g.: in water bottles or jars).

Reverse Osmosis: in reverse osmosis systems, water is forced through a semi-permeable membrane under pressure. Since water molecules are far smaller than those of all pollutants, forcing water through these membranes (with pores of 0.0001 micron) allows water molecules to go through but leaves practically all other particles behind. It is the finest level of filtration available and the only system able to separate any kind of particle from H2O molecules. This means however that salts and minerals are also removed from the water. Reverse osmosis systems are traditionally installed to the water pipes, although they also exist as standalone solutions.

What does LANG’s filtration system consist of?

Our filtration system consists of 3 stages, each comprised of a different type of filtration mechanism, so that the tap water has the best chance of being cleaned of all different types of particles, from heavy metals, radioactive particles, microplastics and pesticides, to chlorine, organic matter (e.g.: viruses and bacteria), and pharmaceutical traces (e.g.: antibiotics and hormones). The stages consist of:

  1. Sediment filter: filters out all larger particles and dirt in order to protect the reverse osmosis membrane from sediment build-up that would shorten its life span and reduce efficiency.

  2. Activated Carbon filter: removes chlorine and other particles that create bad taste or odor in water.

  3. Reverse Osmosis: capable of filtering our any particles left in the water after the first two stages.

Because we wanted to use the most effective cleaning technology available, we chose to include an R/O membrane. However, we also wanted our water to be tasty and healthy to drink, which is why our system not only purifies water, but also automatically adds back a healthy mix of salts and minerals to it.

Our system is plug-and-play: it needs only be connected to a power source and requires no installation or connection to a drain or tap.


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