How to Choose a Whole House Water Filter?

Author: Rory Mullan - Published: 2021/09/03 - Updated: 2022/11/08

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If you’re reading this, you’ve probably covered the first step which is determining whether you need a whole house water filter or not. While these systems offer many benefits, it’s not exactly easy choosing one, given there are just so many varieties.

Also, you can’t just ask a neighbor or friend which brand or type of whole house water filter they use, as their needs may be different than yours. So the burden of finding the best unit for your house falls solely on you.

It’s understandable to be overwhelmed, considering you’re probably about to spend several hundred to thousand dollars. However, we’re here to help. This article will answer all your questions.

So, here is our guide on how to choose a whole house water filter!


The four crucial steps for selecting a whole house water filter are as follows:

  1. Have your water source analyzed to determine its quality.
  2. Choose a filter that can get rid of any toxins and impurities you want to get rid of based on the test findings. Be mindful of NSF standards.
  3. Depending on your water demands, select the appropriate system size. A filter that is too small may cause the water pressure in your entire house to drop.
  4. Think about space and budget constraints.

Quality: How Clean is Your House Water?

Before you start looking for a whole house water filter, you should first take a step back and determine the quality of your water at home.

Why is it important? Well, not all filters are created equal or for the same purpose, so testing your water quality and what it would take to improve it will immensely help your buying decision. It will essentially narrow down your choices to the whole house filters that you exactly need.

Common Contaminants in City and Well Water

Just to give you an idea of what contaminants you might be dealing with, let’s look at common contaminants in city and well water. These are the two main types of water supplies to homes in the US.

City water is usually safe but not completely free of contaminants. While the Environmental Protection Agency (EPA) requires municipalities to filter water, it doesn’t regulate all the stuff it may contain.[1]

Unfortunately, the quality of water can also vary from county to county, as some local governments take stricter actions for safer water.

Most commonly, you might need to filter chlorine, chloramines, and other chemicals in your city water. Lead could also be an issue.

On the other hand, if your water comes from a private well, you may need several layers of filters to deal with sediment, rust and iron.

Well water can also contain biological contaminants. In fact, one recent report found E. Coli in well water. Besides that, this kind of water often contains high levels of minerals known as scale that may need removal.

Testing Your Water

As you can see, there’s a serious possibility of harmful contaminants in both types of water, city and well. However, to be certain, you need to have the water tested for all contaminants – that’s what we recommend.

If you get city water, the easiest way to find more information is to ask the local municipality to give you a copy of the test results of the local water. Often, these reports are available on the municipality’s website.

For more accurate and authentic analysis, it’s best to get the test done by a third-party lab. That’s also the only way for you to determine the state of your water if you’re getting it from a well.

Such tests are usually not that expensive and help you understand exactly which contaminants are alarming.

woman in testing laboratory holding dirty water glass

What is the End Goal with Whole House Filtration?

Again, whole house water filters come with all kinds of bells and whistles. Conversely, some are rather simple. Once you have the test results, you need to decide what you want from your water filtration system.

Is your water contaminated but also tastes bad or has an odor? Does it have a lot of sediment that chokes your pipes and faucets? Is your water very hard?

Let’s discuss some of these goals.

Chlorine Taste/Odor

If your water test indicates a higher level of chlorine or other chemicals, you’ll need to invest in a carbon filtration system (carbon adsorption). Similarly, if you’re dealing with smell in your water, this filter type is your best bet to getting odor-free water.

Carbon adsorption filters are very common in whole house water filtration systems. They deal with all the chemicals, both minute and bigger.

By the way, it’s imperative to deal with chlorine as even if you’re not ingesting it you may inhale it when the water evaporates in your surroundings. Yes, that could happen even when you are taking a shower!


If you have a private well, there are higher chances that you’re dealing with a lot of sand and dirt in your water. Not only are these particles bad for the plumbing system and appliances, they can also make the water a bit murky.

A whole house sediment filter would be necessary to deal with this situation. It’s typically the first line of defense in whole house filtration systems before passing the water onto other filter media.

Metals and Minerals

A higher than normal quantity of metals and hardness minerals in water can be worrisome.

Higher quantities of calcium and magnesium make the water hard. This water condition is not good for your skin and hair. It can also damage your clothes in the washing machine. What’s more, hard water can wreak havoc on your pipes and home appliances by building scale on their surfaces.

Whole house water filters can help with some of the hardness, but to deal with it entirely you’ll need a water softener. Water softening is a whole other process and is different from filtration. That said, some whole house water filters may also incorporate a softening stage.

Similarly, a higher concentration of iron can also be dangerous – not for you but your home. This requires special iron filters, which mostly use pre-oxidation combined with specialized filter media.

If there are other metals in the water in more than average concentration, you may require special filters for those too.


Although lead is also a metal, it’s a nefarious contaminant that requires attention. There have been cases of lead contamination in city waters in the US before, with Flint, Michigan, being the most prominent incident.

Whole house water filters typically don’t deal with metals like lead very well. But there are a few methods that have proven to be effective.

Whole house reverse osmosis systems can also eliminate lead from water.

How to Choose a Whole House Water Filter: More Things to Consider

How to Choose a Whole House Water Filter Thumbnail

Finally, you need to consider the following when choosing a whole house water filter.

The Type of Filter

Based on the information above, now you can decide exactly which type of filters/cartridges you need in your whole house system.

For example, if you’re just dealing with chlorine or another chemical, you need a carbon filter, but not necessarily a sediment filter. If you’re facing dust, rust and sand, it’s the opposite.

So make sure the whole house water filtration system you’re choosing has the right type of filters or filter media to deal with the contaminants you have in your water.

NSF/ANSI Testing and Certifications

The National Sanitation Foundation (NSF) issues safety and health standards. It has various certifications for water filters and other appliances. If the whole house filter of your choice is NSF-certified, you can be sure that it has met or exceeded the minimum safety and efficiency requirements.

This is not necessary, but it helps the company’s credibility and gives you peace of mind that the system you’re buying is, indeed, reliable. Certified products often have seals indicating the testing and approvals.


Whole house water filters also vary by size. So you should ask yourself if a system can provide enough clean water for your home.

This ultimately depends on the number of people in the house, as well as the number of bathrooms, appliances, and kitchens (if you have more than one).

This is important because choosing a smaller-sized filter could result in a drop in pressure and may even take a toll on the system’s performance. Conversely, getting something way bigger than your needs is just throwing extra money at it.

But how much water does your household actually use? Here are some guidelines:

  • A toilet may utilize 2 to 5 gallons per flush (older toilets even more)
  • A showerhead can produce 2.5 gallons of water per minute (15-minute shower = 75 gallons)
  • The washing machine uses nearly 25 gallons per load.

For an average-sized family, a whole house water filter with a flow of 8-12 gpm is more than enough. For bigger families (more than five individuals), a flow rate of 15 gpm or higher is necessary.

For a more accurate estimate of your water usage, you can use this online tool.

Micron Rating

You’ll also come across micron ratings when buying whole house water filters. They basically indicate the permeability of the filter. A higher micron rating shows that a filter is capable of filtering bigger particles. Filters with smaller ratings can also trap smaller particles.

collection of whole house water filters

For your consideration, a sediment filter is typically 10 to 50 microns. It can withhold sand, dirt, and debris easily but may not trap other contaminants which are smaller, like viruses.

For those other contaminants, you’ll need a filter with a lower micron rating, 1 micron for example.

But, such a small rating can negatively impact output pressure, which is why some whole house filter systems have built-in pumps to restore or increase the water pressure.

Whole house RO systems have by far the smallest micron ratings, going as low as 1/10,000 (0.0001). They only work in conjunction with pumps at the point-of-entry level.


Whole house water filters are generally very expensive, costing up to thousands of dollars. Nevertheless, you have to decide how much you can spend.

Also, when selecting a filtration system, don’t just take into account its retail price. You also need to consider installation charges, which can range anywhere from a few hundred dollars to over a grand. Being handy with tools is a clear advantage here and can save you a lot of money.

Surely, a home filter system will pay for itself in time. More importantly, these filters are low maintenance. So once installed, the maintenance cost isn’t as high.

Bottom line, take into account all costs when deciding which device to pick for your house.


Do you have enough space to install such a system? Whole house water filters are big appliances that require space either inside the house or outside.

They are installed at the point of entry where the water supply to the entire house is located. This point varies by the house; some homes may have it inside, while some may have it outside. Of course, installing indoors is much better as the appliance is protected from environmental damage.

Make sure that you have adequate space near the entry point for the whole house filter to sit.


In conclusion, choosing the right whole house water filter starts with determining the quality of your water supply.

There are different approaches for how you can do this; the most obvious one is testing.

Then you need to ask yourself the question, what is it that you want to achieve with a whole house water filter?

Do you just want to improve how your water tastes and smells? Do you want to remove a certain contaminant? Or do you want to remove anything that could be remotely harmful to have the cleanest and healthiest water possible?

Other things to consider for how to choose a whole house water filter is filter type, NSF testing and certifications, system size, micron ratings, price and required space.

Further Reading


Meet Rory Mullan

Rory Mullan Rory has joined the Water Masterz team as a contributing writer. He has covered all sorts of topics in the last several years.

Outside of his writing work, Rory enjoys photographing the Irish landscape and making music!

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