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There are very few household appliances that offer as much benefit as a whole house water filter. But what type of system do you need, and how does it fit your unique water problem?
In short, there are around ten types of whole house water filtration systems, respectively utilizing a different technology. Each features the ability to remove a specific set of contaminants.
However, no filter removes all contaminants, and therefore it’s essential to know exactly what each type of filtration is capable of doing. To make your decision simpler, here we list:
We shall also discuss the advantages and disadvantages of each whole house water filter type to help you figure out precisely what you need.
Your decision to select a whole house water filter system will depend mainly on the biochemical properties of your water, water pressure, type of plumbing in your house, and lastly, your expectations from it.
Most advanced whole house filters feature a robust combination of various filtration techniques to ensure meticulous contaminant removal. Some are based on single-stage filtration, while others may use multi-media treatment.
As the name suggests, sediment filters target undissolved particles like sand, clay, flecks of rust, and debris. The filter acts like a physical barrier that stops larger particles from infiltrating your water supply.
These mechanical filters feature a sieve-like media that blocks contaminants according to their size. They are available at different micron-rated capacities, down to the sub-micron level. For reference, a human hair is 70 microns.
Activated carbon is the most popular whole house filter media since it adsorbs numerous contaminants and improves the taste and smell of your water too. Carbon-based filtration systems remove chlorine, bad tastes, odors, and chemicals like THMs, herbicides, and pesticides.
Activated carbon – it’s also known as activated charcoal when derived from charcoal – is a form of carbon that has been treated to expand its surface area and become highly porous.
There are two types of carbon-based filters:
An activated carbon block is made by tying fine carbon powder using a bonding agent. In contrast, GAC filters contain loose granules of activated carbon. While an ACB filter is more restrictive, water can pass more freely through GAC.
Therefore, GAC filters are more popular in whole-home filtration systems as they allow higher water pressure. At the same time, they won’t reduce as many contaminants as a carbon block.
Catalytic carbon filters are more effective at removing chloramines, a somewhat problematic contaminant.
Most water utilities are now using chloramines instead of chlorine to disinfect their water since it’s more stable. Compared to activated carbon, catalytic carbon retains an enhanced capacity to catalyze chloramines into chloride, leaving ammonia behind.
KDF, Kinetic Degradation Fluxion, features a unique redox reaction based on the process of oxidation and reduction. A combination of copper and zinc is used to construct the filter media that’s often used to enhance the performance of other media layers in a whole house water filter system.
KDF can remove/reduce chlorine, lead, mercury, hydrogen sulfide, chromium, and more. Plus, it controls bacteria, algae, and other microorganisms.
There are two recognized types of KDF filter media:
You may have already noticed, all filtration techniques have limitations. By adding KDF to a carbon-based system, a whole house water filter can target a much wider range of contaminants.
Water softeners use ion exchange for the process of separation of certain minerals, mainly calcium and magnesium, causing water hardness.
But since calcium and magnesium aren’t contaminants but healthy impurities, water softeners aren’t technically classified as water filters but as water purifiers.
Still, a whopping 85% of the USA has hard water. Therefore, water softening systems are one of the most commonly used water treatment devices. That’s because removing calcium and magnesium reduces scale buildup inside pipes, water heaters, and fixtures. Besides, it leads to better skin and hair.
Other types of ion-exchange systems which we consider whole house water filters in the real sense utilize similar technology like water softeners, but are designed to target specific contaminants.
Water that is high in iron often has a high percentage of manganese and sulfur too. Therefore, iron filters usually target all three and use different filter media to purify your water effectively.
High iron content in your water supply will show up as brown stains on your laundry, stained pipes, and foul-tasting water. Whereas a rotten egg-like smell from your water signifies the presence of hydrogen sulfide (sulfur).
While you may be confident that your water supply has high iron content, it’s best to test the water to figure out the exact iron concentrations and the presence of other co-existing contaminants. Moreover, iron can be present in two forms:
Ferrous iron is dissolved in water and must first be made insoluble to make it visible and easy to remove. The most common way to make iron insoluble, or solid, is to expose it to oxygen. This process is called pre-oxidation, which is the first step in an iron removal filter.
Here are a few methods of pre-oxidation:
Once all iron is solid, it can be filtered out relatively easily using various types of filter media such as catalytic carbon or greensand. Greensand filters are also very efficient at removing manganese and sulfur.
Acid neutralizers aim at balancing out the pH level of your water supply. Low pH not only contribute to poor water flavor but also increase the risk of metal contamination due to corroding pipes.
The technology uses natural minerals to increase the ph level of your water to make it less acidic or even neutral/alkaline. Also known as calcite filters, these whole house water filtration systems use calcium carbonate and magnesium oxide to neutralize the water.
As water passes through the media, a small part of it dissolves and mixes with the water. Once the water leaves the filter, it should be alkaline and safe to use.
Some acid neutralizers backwash the filtration media, which is usually needed if your water is also high in iron.
Activated alumina doesn’t filter the contaminants; it adsorbs them. This type of whole house water filter is mostly used to treat water with high fluoride or arsenic content. AA filters are also designed to remove selenium, uranium and thallium from your water supply.
The filter media features a highly adsorptive material: Aluminum hydroxide, with a surface area as large as 200 sqm per gram.
As water passes through the activated alumina granules, it can absorb up to 10 ppm of fluoride. But this also depends on the contact time between media and water.
Reverse osmosis filters offer the most comprehensive removal of water contaminants. Water is passed through a semipermeable membrane that rejects many different kinds of contaminants, including heavy metals like lead, nitrates and other salts, pesticides, pharmaceutical run-offs, bacteria, and arsenic.
Thus, RO systems are unrivaled in their potential to remove a long list of contaminants, but unfortunately, they come with a fair share of setbacks.
No matter how advanced a whole house RO system, it is notorious for producing a significant amount of wastewater to carry out the purification process.
The water that is free of harmful contaminants is called permeate, and the leftover concentrate is called brine. For each gallon of permeate, a whole house RO filter produces up to 4-5 gallons of brine.
Moreover, RO membranes are prone to contamination due to hardness, chemicals and chlorinated water, so pre-treatment is essential to prevent fouling.
UV filters feature ultraviolet light that targets microorganisms like viruses, bacteria (e.g. E Coli), and cysts (cryptosporidium, giardia). These contaminants are infamous for disrupting gut health and expose your body to a host of illnesses.
The filter exposes the water to germicidal ultraviolet light that alters the DNA of living organisms rendering them harmless. UV filters are also generally effortless to maintain.
However, they don’t “filter” anything out; they only inactivate microorganisms trying to sneak into your water supply.
UV filters are safe and chemical-free, but on their own they are not the best options for whole house water filtration. First, this is because UV light fails to work on muddy or unclear water. Secondly, UV light doesn’t remove any harmful contaminants.
Their potential to manipulate bacteria etc. make them excellent post-filters in a whole house water treatment system.
Ultrafiltration whole house water filters entail similar technology as a sediment filter. Using a mechanical barrier, these systems can remove particles as small as 0.02 microns.
A hollow semi-permeable fiber sheet acts as a physical barrier to remove microscopic pathogens like bacteria and viruses. Similarly, ultrafiltration is very effective for the removal of some pesticides and even lead (partially).
However, ultrafiltration fails to filter dissolved solids like salts and fluoride. Therefore if your water has a high TDS level, it won’t be a good idea to use a standalone ultrafiltration system.
Whole house water filters are either cartridge-based or tank-based. Tank-based filters often apply backwashing to prolong their service life.
Both whole house filtration system types feature a few advantages over the other.
If you have any questions about the different types of whole house water filters please don’t hesitate to leave a comment below!