- Phase 1: Filtration – Water flows through a large tank filled with filter media. Contaminants are trapped.
- Phase 2: Backwash – Water is moved in reverse direction through the tank (backflushing), forcing the filter media to expand. This dislodges all accumulated dirt and flushes it down the drain, leaving the media clean and ready to purify more water.
How Do Whole House Backwashing Filters Work?
While a backwashing filter may look like a water softener, it is an entirely different unit. Water softeners remove magnesium and calcium from hard water, preventing scale buildup on plumbing fixtures. On the other hand, a backwashing filter utilizes purification techniques to remove impurities (like pesticides and lead) and treat contamination.
Whole house backwashing filters operate in two phases. The first phase is known as the filtration process, while the second one is referred to as waste removal or backwash. Below, we’ll discuss both in detail.
Phase 1: Filtration Process
Any backwashing filter uses a large tank often referred to as “mineral tank.” The tank is filled with a substance that serves as a filter medium.
The water enters through a control valve in the top of the tank. As the water flows through the tank, the filter media traps the contaminants. Depending on the type of media, these can be chemicals (chloramine, chlorine, pesticides), sulfur, iron, and so on. There are even backwashing filters that neutralize acidic water.
So, the untreated water passes through the media bed, which either eliminates contaminants or alters them. After this, the clean, pure water flows into your home and is ready to be utilized.
Phase 2: Backwash
In the second phase, the backwash filter cycle starts. This can be programmed to take place automatically or you can initiate backwashing by hand.
Water moves through the whole house filter system in reverse direction, a process known as backflushing.
When the water flows backwards, the filter media expands. All accumulated contaminants are flushed down the drain, leaving the media clean and ready to purify additional water.
The backflushing continues for a set time. At the end of the cycle, water flow goes back to normal so that the media bed can return to its initial configuration. In some cases, the filter media is also repacked by a fast rinse.
Usually, it takes around 5-15 minutes to complete one backwash cycle.
Why Is Backwashing Important?
Ineffective backwashing is a typical reason behind failed water filtration systems.
Depending on the water quality, the filtration bed of a whole house filter accumulates many impurities and dirt over time. Often, larger contaminants build up on top of the bed forming a filter cake, while smaller particles make their way down the filter bed.
Both can cause the filter media to clog. Without backwashing, the result would be a water pressure drop throughout your home and eventually bleed-through of contamination into the freshwater supply, which is unquestionably the worst possible scenario.
To avoid such risky conditions, the use of backwashing becomes essential. In addition to self-cleaning benefits, backwashing has several other advantages:
- It reduces pressure changes and maintains filtered water flow.
- It acts as a rejuvenating process, cleaning the media surface by removing impurities that renew the filtration capacity.
- It releases filtration space in the filter bed and facilitates aeration, which further enhances the reabsorption capabilities of the filter media.
- Backwashing also prevents germs like bacteria and mold to grow inside a whole house water filter system. This translates into a dramatic reduction in odds of infection in treated water utility sources.
How Often Should Whole House Water Filters be Backwashed?
As described above, during filtration, the filter media gets accumulated with contaminants. If you let this continue for too long, flow rates in the filter system will drop and so will pressure in your water outlets.
Thus, how often you should backwash your whole house water filter depends on the unit itself, your water conditions, and your water usage.
For example, an iron filter removing 12 ppm of ferrous and ferric combined might need to backwash every 3-4 days. A whole house carbon water filter removing chemicals from city water can go 1 to 2 weeks without backwashing.
When in doubt about how to program your system, you should consult the seller or manufacturer.
You can also install pressure gauges before and after the filter. Typically, you should perform a backwash when the pressure drop exceeds a specified maximum value (generally 16 psi for the whole system). You can do so by pressing the regen button on the system’s home screen. Nevertheless, to manually start a regeneration cycle, the valve must be in the treatment position.
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What Are the Common Types of Backwashing Whole House Water Filters?
Water impurities can be differentiated into two main types:
- Dissolved compounds or minerals that cannot be seen by the naked eye
- Dispersed particles in the water that are visibly apparent and make the water look cloudy or dirty
There are various types of filter media to remove either kind of water contamination. Below, we’ll discuss them in detail.
Backwash Filter Media for Sediment Contamination
Here are a few backwash filter media you can use to remove suspended solids that tend to cloud your house water.
Micro Z
Due to its filtration capabilities, Micro Z has a long service life. It can extract micro-sediments between 2 and 20 microns in size.
The media effectively purifies the water because its sediment filtration efficiency is exceptional.
What else is good? The surface quickly modifies, allowing customized zeolites to target certain pollutants.
Filter AG
Of all the water filtering media, Filter AG is readily accessible and widely used, for all the right reasons. It is the most low-cost method of removing debris and silt from water.
Hence, Filter AG is perhaps one of the most viable options among filter media for sediment removal.
Anthracite
This media uses several layers (anthracite, garnet, and sand) to eliminate large and small dirt particles from water effectively.
This one is used explicitly to remove oxidized iron particles, sand granules, solid impurities, and marine sediments.
Backwash Filter Media for Dissolved Compounds or Minerals
Dissolved particles in our water supplies are around 0.02 microns in size. Typically, two processes are utilized to remove these particles: adsorption and absorption.
Adsorptive media attracts all the contaminants to the media surface like a magnet. Absorptive media, on the other hand, pulls pollutants inside of it like a sponge absorbs liquid.
Here are a few backwash filter media used to remove micro-contaminants from your home water.
Bone Char
Bone char is used to remove fluoride from water. While fluoride is used to protect against tooth decay, an excess amount could result in fluorosis, deteriorating teeth, and bone issues.
In severe cases, it could even lead to skeletal problems. Therefore, some people find it essential to get rid of fluoride in their home water.
Bone char is produced by charring animal bones. The porous, granular material consists of carbon, tricalcium phosphate, and calcium carbonate. Tricalcium phosphate removes the fluoride.
Granular Activated Carbon
Activated carbon effectively removes chemical pollutants from your house water. The granules eliminate pesticides, chloramine, chlorine, and other contaminants.
Also, if your water has a bad odor or foul taste, GAC (Granular Activated Carbon) will get rid of both.
Catalytic Carbon Filters
Catalytic carbon is a modified version of activated carbon. The altered surface structure is specifically used to reduce hydrogen sulfide and remove chloramine from water.
While this filter media might be a bit costly, it falls under the category of one of the most effective backwashing filtration media.
Birm
This lightweight absorptive media reduces iron from water. It consists of aluminum silicate embedded with manganese salt.
While Birm is advantageous for iron removal, it works best when the water pH is maintained at 6.7 or above.
Greensand Plus
Greensand is effective for removing hydrogen sulfide, iron, and manganese. Also known as glauconite, Greensand is a siliceous mineral impregnated with manganese oxide.
Potassium permanganate is utilized to activate and clean the catalytic surface during the regen cycle, aiding metal oxidation.
pH Neutralizers
As the name suggests, these backwash filters neutralize acid pH in your water. Put simply, if your water is highly acidic, the filter will change it to slightly alkaline or neutral.
PH neutralizing filters use a form of calcium carbonate known as calcite.
Treating your water with calcite will raise the pH by adding minerals. If your water’s pH is below 6.8, this form of treatment is pretty effective.
Pros and Cons of Backwashing
Today, backwashing filters are widely used for domestic and industrial applications. Below, we’ve discussed a few pros and cons of the systems.
Pros
- Backwashing prolongs the life of the filter media.
- Backwashing filters are pretty versatile, and you can customize them for different kinds of water problems.
- They are not subject to channeling, pressure loss, biological growth, or EBCT leakage over time.
- Their installation is pretty straightforward.
Cons
- A whole house water filter utilizing backwashing requires electricity to function.
- During backwashing, wastewater is drained (although drained water can be utilized for various purposes like irrigation).
- Systems typically have lower empty bed contact times due to using less filter media. That’s because the space in the tank is needed for media expansion. The only solution: Using larger tanks.
- Badly designed filters may disrupt the mass transfer zone.
If you have any questions about whole house water filter backwash please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Gene Fitzgerald is one of the founders of BOS and currently head of content creation. She has 8+ years of experience as a water treatment specialist under her belt making her our senior scientist. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
Learn more about Gene and the rest of the BOS Team.
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