Whole House Water Filter Installation How-To (+ Diagram)

Author: Jason Hollow - Published: 2021/04/15 - Updated: 2023/01/05

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In order for a whole house water filter to provide your entire home with clean water it needs to be plumbed into the main water line. This involves pipe cutting and making new plumbing connections among other tasks.

For experienced do-it-yourselfers, this probably sounds like a great idea for the next project. But even people that haven’t made a lot of experience with hacksaws and plumbing wrenches yet don’t need to browse for the phone number of the nearest installer just yet; because installing a whole house water filter system sounds more complicated than it really it is – as you are about to learn soon!

In our opinion, it’s doable for anyone who is not afraid to get his hands dirty.

So, here is our step-by-step guide on how to install a whole house water filter!


These are the steps for installing a whole house water filter:

  1. Prime filter media if required.
  2. Turn off the water supply.
  3. Release pressure from inside the main water line by opening multiple outlets.
  4. Remove a pipe section and sand off any sharp edges.
  5. Optional: Install gauges and valves for easier maintenance.
  6. Put the whole house filter in place.
  7. Connect the filter to your water main.
  8. Turn the water back on and check for leaks.
  9. Flush the system.

Location: Where to Install a Whole Home Water Filter

Before we get into the practical side of things, what’s the best installation location?

First of all, the closer to the main water line, the better. Ideally, you install a POE filter right at the main supply and avoid additional water lines. Enough space for installation is mandatory. What’s more, the system should be accessible from at least one side for easy maintenance and repairs.

Before or After the Water Heater?

A POE water filter should always be installed before the water heater. This has two benefits:

  1. You have both filtered cold water and filtered hot water. This will improve the service life of home appliances running on hot water.
  2. The water heater’s lifespan itself will increase.

Before or After the Pressure Tank?

Private well owners need to install their water filter system after the pressure tank.

Before or After the Water Softener?

Installing a whole house water filtration system before or after a water softener depends on your water conditions. Usually, for tap water we recommend to install the water filter before the water softener to protect the softening resin which is often chlorine-sensitive. Going filter first also solves any problems with water pressure.

For well water, you may want to go the other way around. Unless you use shock chlorination on your well there’s no chlorine to remove and installing the whole house water filter after the water softener ensure sufficient flow required for system regeneration.

How About Installing a POE Filter Outside?

We would avoid installing a whole house filtration system outside if possible. For one, you need to install in a place where no freezing temperatures occur. And installing in your garage or basement protects your system from potential damage.

Whole House Water Filter Installation Diagram

Whole House Water Filter Installation Diagram

Courtesy of BOS

Supplies & Equipment


Here are the supplies you need when installing a whole house water filtration system:

  • Copper piping or stainless steel flex hoses
  • Solder supplies (if you use copper piping)
  • Plumber’s tape
  • Shark-bite fittings or other
  • Shut-off valves (optional)
  • Bypass valves (optional)
  • Pressure gauges (optional)
  • Mounting bracket (only with modular water filtration systems)


Here is the equipment you need for installing a whole house water filtration system:

  • Hacksaw
  • Plumbing wrench
  • Drill
  • Drill bits
  • Screwdriver
  • Bucket + large towel

How to Install a Whole House Water Filter System

How to Install a Whole House Water Filter Thumbnail

Finally, let’s discuss how to install a whole house water filter step by step.

Of course, you should remember to take our instructions with a grain of salt. Because although the installation process is pretty much the same for most water filtration systems on the market, there may be additional steps required with your model. Thus, make sure to read your product manual thoroughly before you get started.

  1. Carbon and other types of filter media often require priming (soaking for 48 hours). You should take care of this before even thinking about continuing with step 2.
  2. Whenever you’re messing around with your plumbing your first step should be to close the water supply. In our case, it’s the main water supply.
  3. Now, drain all water in the main water line. You can do so by opening all nearby taps and shower heads.
  4. All water flushed out? Then it’s time to remove a section from the main water line. It should be long enough to easily accommodate your water filtration system. Before you start cutting, remember to place a bucket underneath as an added security measure against water damage.
  5. Sand off the ends of both the incoming and outgoing water line.
  6. At this point, we recommend you install a shut-off valve on either side of the filter. This allows for much easier maintenance later on. Instead of shut-off valves, you can also install a whole house water filter bypass which allows you to use still use water even when the filter is in sleeping mode.
  7. One more optional component is pressure gauges. They allow you to measure incoming versus outgoing water pressure. What for? A high pressure drop is a great indicator that one or more of the filter stages are clogged and require your attention.
  8. Next, place the filter where you want to have it.
  9. You need to establish a connection from the incoming water supply to the inlet port of the filter system and a connection from the outgoing water supply to the outlet port. We recommend using flexible stainless steel hoses with push fittings here. This is much more convenient than soldering copper piping. Also, keep in mind that all threaded ends need to be wrapped with plumbers tape to prevent leakage (unless instructed otherwise). Speaking of, be careful not to overtighten any overtighten any plastic fittings to prevent cracking.
  10. All connections established? Then you can slowly turn the water supply back on while checking for leaks.
  11. Finally, you need to flush the system for 3 to 5 minutes to remove any air and installation debris. Flushing may also be required to activate the different types of filter media (consult the product manual).

All in all, we estimate that the installation takes between 3-4 hours to complete. In case you’ve done this before, you might be able to finish the project within 1-2 hours.

In old houses, the plumbing is sometimes used for grounding of the electrical system. In this case, you need to add a so-called jumper cable from one side of the newly installed water filter to the other. This is to ensure that the ground stays intact.[1]

Video Guide

For completing your project you might find the following video useful. It shows how to install a simple cartridge-based sediment filter. However, the general approach is the same.


In conclusion, the installation of a whole house filter system can be challenging but is certainly not impossible. It makes a great DIY project for those who are willing to learn.

The best place to install a system is in your garage or basement at the main water line, before the water heater, after the pressure tank, and usually before the water softener.

Before you get started, you should gather all the necessary supplies and equipment. Then you simply need to follow the instructions as provided in your product manual. For reference, you can check out or instructions from above.

We estimate around 3 to 4 hours from start to finish.

Further Reading


Meet Jason Hollow

Jason Hollow Jason is the founder of Water Masterz and head of content creation. After six years in the industry, he has tremendous knowledge and first-hand experience on all things related to water treatment.

His credo: Not a single American should have to drink unhealthy water at home.

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