How to Install a Whole House Filtration System: Step-by-Step Guide (And Diagram)

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By Eric Phillips


A whole house filtration system provides crisp, fresh drinking water straight from the tap. It also eliminates chlorine in shower water and prevents limescale buildup in pipes. Installing a point-of-entry water filter ensures every drop of water entering your home is pure for drinking, bathing, and washing clothes.

Though the idea of working on the main water line may seem daunting, with the proper knowledge, installing a whole house water filter is a manageable DIY task. The process is the same whether you're connected to the municipal water supply or drawing from a private well. Here's everything you need to learn to install a whole house water filter.

Whole House Filter Location: Where Should I Install?

To install a whole house water filter, the best location is on the main water line that enters your home. This is typically in the basement or garage.

When installing, ensure that it's easy to access for semi-regular maintenance, as filter cartridges need to be replaced every three to six months.

It's also recommended to install the filter before the water heater, as it will protect the heater from minerals, sediment, and bacteria.

When installing a water filter on a well, it's recommended to place it after the pressure tank. This is because if the filter causes pressure to drop, the well pump may work continuously and risk damage. It's worth noting that the well pump is more expensive to replace than the pressure tank.

Lastly, remember that when installing a whole-house water unit, ensure that there is a power outlet nearby if it requires one.

Should I Install POE Water Filter Before Or After A Water Softener?

If your water is highly chlorinated, it's better to place your filter before the softener. If your water softener requires a higher pressure for backwashing, you should place your filter after your softener to maintain that pressure.

Basically, it depends on whether it’s more important to protect your water softener from contaminants like chlorine and sediment or to protect your whole-home water filter from the minerals your water softener removes.

If you're using a municipal water supply, it's likely to be chlorinated. This chemical damages the ion exchange media in your water softener, so it's better to place the whole-home filter upstream of the water softener. This will boost the lifespan of your water softener.

If you're drawing water from a private well it's unlikely to be chlorinated (unless you're adding it yourself). In that case, it's a good idea to install the whole house filter after the water softener. This will prevent hard water minerals from clogging your filter and preserve the maximum water pressure for backwashing your water softener.

If you're buying one of the best whole house water filter and softener combos, you don't need to worry. With combination models, the water softener is sandwiched between a KDF media filter stage that removes chlorine and the latter filters that could be damaged by hard water. This is the best of both worlds.

Can I Install My Whole-House Water Filter Outside?

You can install your whole-house filter outside, but it's recommended to install it in a protected area such as your basement or garage to prolong its lifespan. Exposure to the elements and freezing temperatures can cause damage to the point-of-entry water filter.

Parts & Tools For POE Water Filter Installation

Gather all necessary tools and parts before starting the installation process. This will prevent delays caused by waiting for hardware stores to open for additional supplies.

Consider purchasing a DIY installation kit from the manufacturer of your whole-house water filter system. These kits may be included in the original product or available as an optional add-on. They typically contain bypass valves, O-rings, and other fittings that make installation easier.


  • Filtration system and included components
  • Mounting brackets
  • Tubing and push fittings
  • Two shut-off valves
  • Optional: bypass valve, pressure gauge (two), plywood board for mounting, copper wire for grounding (older homes only)

Required Tools:

  • Drill and drill bits
  • Adjustable wrench and pipe wrench
  • Screwdriver
  • Pipe cutter or hacksaw
  • Bucket
  • Plumber's Tape
  • Optional: soldering kit

How To Install a Whole House Water Filter System (Step By Step)

The process for installing a whole-house water filter is similar for all types no matter which of the best whole-house water filters you choose. Let’s get started.

Part A: Preparation

  • Step 1: Turn off the main water supply to your home at the stopcock or water shut-off valve.
  • Step 2: Drain the remaining water from your pipes by turning on all faucets and letting the water flow until it runs out. If you have outdoor faucets downstream of the water shut-off valve, turn them on as well.
  • Step 3: Cut into the main water line at the point of installation and remove a section of pipe that's large enough to contain the new filter. Make sure the filter fits and keep a bucket handy to catch any residual water.
  • Step 4: Sand down the rough edges (burrs) remaining from the cut pipes.
  • Step 5: Inspect the pipes for debris and remove any found.
  • Step 6: Install a shut-off valve on either side of the water filter for easy maintenance. Decide whether to install a water filter bypass valve as well.
  • Step 7: If desired, install a pressure gauge next to each shut-off valve to monitor filter performance and know when to change the filter cartridge.
  • Step 8: If mounting the filter system to a plywood board, attach the board to the back wall.

Part B: Mounting The Filter

  • Step 9: Install the whole-home water filter using flex piping. Ensure the In and Out ports are facing the correct direction. Use adaptors and push fittings to balance piping sizes if needed. Do not overtighten any plastic fittings and use Teflon tape to seal all threaded ends to prevent leaks.
    • If you’re choosing to solder your unit in, thoroughly clean the pipe ends first and keep your soldering iron away from any plastic fittings. We’ll have a note on soldering at the end.
  • Step 10: Rinse the inside of the filter unit to remove debris. Check the manufacturer's guidelines for any filters that may require flushing with tap water before use. Grease the O-rings that hold the filters in place and ensure they fit tightly.
  • Step 11: If the whole house filter requires power, plug it into an outlet at this stage.

Part C: Checking Your Filter

  • Step 12: Open all valves except the bypass valve. Turn the water back on at the main shut-off valve.
  • Step 13: Check every connection you made for leaks. If you find one, carefully tighten the fittings and filter housings as needed.
  • Step 14: Install a jumper cable to keep the ground intact if your home uses plumbing for grounding the electrical system. Connect the copper wire from one side of the filter to the other using grounding clamps.
  • Step 15: Follow the manufacturer's instructions for activating the filter media. Most systems require flushing to remove dust and sediment from the filters.


If you are not experienced in soldering, using push fittings to make connections is recommended. It will make the installation of a whole-house water filter less challenging.


Grounding creates a conductive pathway between your electrical system and the earth, allowing excess electricity to have a safe route out of your home, protecting your devices and home in case of an electrical surge. In older homes, the metal plumbing system is used for grounding. When cutting the main line, it's essential to reinstate it after installing the water filter.

How To Install A Whole-House Water Filter System On A Well

  • Step 1: Shut off the water supply to your home and drain the system by opening all the faucets.
  • Step 2: Cut a section of pipe out of the main water line to install the well water filtration system.
  • Step 3: For systems that require backwashing, such as well water softeners and iron filters, add a drain line to remove dirty water.

Note: The exact installation process may vary depending on the specific well water filtration system chosen, but it’s likely to be similar whether you’re on a private water supply or municipal water system.

Wrapping Up…

Congratulations on installing a whole-house water filter, whether you're a first-time DIYer or an experienced handyman. DIY plumbing can be intimidating, but doing it yourself can save you money, especially when you've invested in a premium POE water filter.

You've completed the thirsty work of installing a whole-house water filter, now it's time to enjoy the benefits of fresh, crisp, and delicious drinking water on tap. Enjoy the fruits of your labor.

Eric Phillips

Meet Eric, the Water Treatment Specialist and founder of Dripfina, where he shares his wealth of expertise. With notable features in Realtor, ApartmentTherapy, FamilyHandyMan, and more, Eric is a renowned expert in water treatment industry. Join Eric on Dripfina and benefit from #AskDripfina community to make informed decisions for clean, refreshing water.

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