Water Filtration Series #1: A Guide to Whole House Filters
With such a variety of water filtration products on the market today. The term "whole house water filter" can mean different things to people. So, choosing the right filtration method is crucial for our water. Are you filtering water for the entire home or just for drinking water? For homeowners, the term "water filter" may refer to a whole-house filter housing at the point of entry (POE), an under-sink filter for point of use (POU), a faucet-mounted filter, or even a refrigerator filter. For water treatment professionals, it may refer to a whole-house sediment filter housing or a whole-house filtration system that removes iron, odor, manganese, arsenic, lead, chlorine, turbidity, bacteria, sand, a UV system, VOCs, and PFAS, along with a litany of other potential water contaminants.
In this guide from our Water Filtration Series, we clear up the confusion and focus on one of the most misunderstood yet common filtration options: whole-house water filters and filter housings.
We'll explain:
- What water filtration housings are
- Common types and sizes
- When to use them (and when not to)
- Alternatives like Rusco spin-down filters
- Maintenance and installation tips
- How to choose and maintain the correct water filtration solution for clean, consistent, and reliable water quality throughout your home.
What Are Water Filter Housings?
A water filter housing is a durable container that holds a replaceable filter cartridge. Filter housings are available in various sizes to accommodate plumbing sizes, water flow volumes, and contaminant removal applications. Typical residential filter housing fittings are in plumbing sizes from 3/4" to 1 1/4". Common residential filter housing sizes include:
- 2.5" x 10" slim line housings (for under sink use only)
- 2.5" x 10" standard housings (for under-sink or small whole-house filtration)
- 2.5" x 20" whole-house filtration (longer filter lifespan and higher flow rates)
- 4" x 10" whole-house filtration (longer filter lifespan, more filter options, higher flow rates)
- 4" x 20" Big Blue housings (longer filter lifespan, more filter options, higher flow rates)
When paired with the right filter cartridge, these housings can reduce rust, sediment, chlorine, odors, and even lead. But they’re not always the best or most efficient solution for whole-house filtration or drinking water filtration.
The Problem with Replaceable Filter Cartridges
- Short Lifespan: Filter cartridges clog quickly in poor water conditions, leading to frequent (and costly) replacements, repairs, and premature failure of water treatment systems.
- Reduced Flow & Water Pressure: As filters clog, they reduce water flow rate and pressure. Using finer micron rating filters causes them to clog faster, reduces water flow, and reduces the water flow needed to operate water treatment equipment and run a household.
- Limited Effectiveness: Many filter cartridges offer minimal contaminant reduction or become clogged quickly, making them costly and less efficient.
- Choosing the Right Water Filter Cartridge: Whole House Use or Undersink Drinking Water. Choosing the right water filter depends entirely on what's in the water and what needs to be removed or reduced for the particular contaminant.
When a Water Filter Housing Still Makes Sense
Despite the limitations of filter cartridges, there are scenarios where they are essential:
- An example of this is Flint, MI, where lead contamination from outdated water lines to homes became a severe health issue. Under-sink carbon block filters were installed in all homes with lead water lines, which run from the street into the homes to reduce lead, turbidity, and chlorine, ensuring a clean source of drinking water until the lead water lines to their homes could be replaced.
- Any homeowner on city water should strongly consider adding, at minimum, an undersink filter to remove chlorine and the many contaminant byproducts it produces for clean, worry-free drinking water. An undersink filter can either have its own dedicated faucet or be plumbed directly to the cold water supply of the kitchen faucet. Having a separate, dedicated faucet for drinking and cooking water will prolong filter life and ensure better water quality.
- A whole-house activated carbon/KDF filter tank is the best option for quality water throughout the house.
- Homes with steel-cased wells that require sediment and scale removal.
- New wells often release sediment and sand for months after drilling, making whole-house (POE) filters necessary.
- Sanitizing the household plumbing, whether it is galvanized, copper (which are less inclined to contamination or plastic pipes (CPVC, PVC, PEX), which are more prone to bacterial contamination.
- Anyone with a private well for their main source of water should sanitize their plumbing lines annually with one quarter cup of bleach in a pre-filter housing, by-pass all water treatment equipment, go to the furthest faucet, run the "cold water" until you smell bleach, shut it off, and work your way back to the closest faucet to the filter housing, running faucets until you smell bleach, shut them off and let the chlorinated water sit in the plumbing lines for 1-2 hours. Then run all the faucets again to flush out any residual chlorine and turn the water treatment back on.
- By doing this annually, it reduces the potential for bacteria and biofilm to build up in the household plumbing, which helps prevent possible health issues from water contaminated with bacteria and/or biofilms.
Alternative Whole House Sediment Filters: Rusco Blow-Down Filters
Rusco (blow-down) filters trap sand & sediment and can be flushed clean — no cartridge required. Ideal for homes with heavy particulates. Maintenance involves monthly flushing, extending the life of downstream equipment.
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Choosing the right filter for the water problem:
Sediment Filter Cartridge Types and Uses:
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| Sediment Filter Cartridges |
- Fine Micron Filtration: 5 Micron Fine particulate removal. Typically used in pre-filtration for reverse osmosis drinking water systems and ultrafiltration systems (available in polyspun or cordwound filament) or as a 5-micron block carbon filter for undersink drinking water filters. Not recommended for whole-house use.
- Sediment Filters: 10–50 Microns Used in whole house filter housings for the removal of sediment, reduction of iron, and before water treatment equipment. (available in cordwound, pleated, or polyspun filament).
- Recommended Filter Micron - A 20-micron sediment filter is typically used for whole-house filtration
- DGD (Dual Gradient Filters): Dual gradient filters typically have a micron rating from 25 microns to 1 micron. Larger particulates are removed on the outer layer of the filter, and particulate removal progresses through the filter to 1 micron near the inside of the filter cartridge. DGD filters are used in 4" x 10"- 20" filter housings only.
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Carbon filters are best for removing chlorine, chloramines, trihalomethanes, taste, and odor for
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| Carbon Filter Cartridges |
Activated Carbon Filters: Chlorine, taste and odor, VOCs, radon, removal, and more. There are many types of activated carbon. EG: Coconut shell carbon (The most commonly used carbon), Granular carbon, Catalytic carbon,
Carbon Block Filters: Lead reduction, chlorine removal, VOCs removal, and heavy metals.
Chloramine Filters: Chloramines (a chlorine/ammonia mix used in city water) require specially-formulated carbon media. Not all carbon filters are rated for chloramine removal—always check NSF certifications for proper filter applications.
Learn more about choosing the right water softener
Maintenance Tips:
- Replace filters every 3 months or sooner. Depending on water quality
- Shut off the water & relieve pressure before removing the filter housing
- Clean & sanitize the filter housing with a tablespoon of bleach each time
- Clean, lubricate & replace O-rings as needed
- Hand-tighten filter housing only - avoid overtightening the filter housing as it will flatten, pinch, or cut the o-ring, causing leaks
- Keep a bucket handy to catch water while relieving pressure from the housing and removing the filter housing
- Keep a tube of food-grade silicone nearby. (see the link below for food-grade silicone)
- Keep extra O-rings hanging on the wall with the filter wrench
- Pentair: How to change a prefilter
Installation Best Practices:
- Mount the filter housing securely to a wall with a mounting bracket
- Install shut-off valves before & after the filter housing
- Look for filter housings with built-in shut-offs & pressure relief buttons
- Do not mount water filter housings near or above any electrical outlet or well switch
- Have a hook mounted on the wall nearby to hang the filter housing wrench
- An improper installation of a filter housing not only leads to problems when getting the housing off to change filters, but can also lead to catastrophic plumbing problems.
✸ Out of the hundreds of photos I searched on the internet, I could not find a single picture of a pre-filter housing that was installed properly. So I created my own AI version of a properly installed whole-house filter. That says a lot about the lack of training and professionalism in the water treatment industry and the lack of knowledge with DIY installations. This has always been one of my pet peeves. When I am out servicing another company's equipment or a homeowner's DIY installation. There have been many times I've refused to touch a filter housing because I knew it would lead to a plumbing failure and/or leak. Which would then be my responsibility to repair and pay for. One of my favorite mottos is "Just do it right the first time." It leads to fewer headaches and fewer repairs down the road.
What’s Next in The Water Softener Blog?
In our next article in the "Water Filter Series #2", we’ll explore whole-house filtration systems and water flow-metered regenerating filters — solutions that tackle iron, sulfur, arsenic, and more at the point of entry (POE). The different types of filtration options and which ones work best for the water you have, and what is best for your home and family.
Stay tuned and subscribe to The Water Softener Blog for expert insights on making your water safe, clean, and trouble-free.
Related Articles:
How Water Softener Systems Work |
Choosing the Right Water Softener |
Arsenic in Well Water
NSF Water Filter Certification |
EPA Drinking Water Standards |
CDC Well Maintenance
I wish you Good days and Good water!
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