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Project Guide

How to Install a Whole House Water Filter

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1
Choose the Filter Location
Main water supply shut-off valves on copper pipe in a basement.

Whole house water filter systems often have a sediment pre-filter unit and a second filter unit. The pre-filter catches dirt and rust particles. The second unit contains a carbon filter that removes other contaminants. When installing a water filter, the first step is to choose a location that is easily accessible.

  

  • You’ll need to access the unit to regularly change the whole house water filter cartridges, so be sure no obstacles interfere with installation.  
  • Select a position near the main water shut-off valve. Keep in mind that a filter mounting bracket will be secured to either a wall or floor joist.  
  • The water filtration system should be installed in-line with the existing plumbing line. Look for a horizontal run after the home’s main shut-off valve, before it branches off to other parts of the house. If you don’t have a horizontal section that’s appropriate, you can tee-off of a vertical section and mount the filter system beside it. 
  • If you are learning how to replace a whole house water filter, you can likely reuse the location and connections of your current filter, so long as your new filter matches its dimensions.
  • Check the manufacturer’s recommendations for your filter model’s clearances and dimension specifications. 
2
Remove a Section of Pipe
A person using a deburring tool to remove burrs from a cut copper pipe.
  • Turn off the water supply. If your house has a drain valve just after the shut-off valve, hook a hose up to it and drain the system into a sink, a bucket or outside. Open a fixture in the upper floor to ensure all the water drains out.  
  • Next, mark a section of pipe to remove in order to accommodate the filter system. 
  • If your whole house water filter consists of a single unit and does not include a separate pre-filter, refer to the template included with your filtration system. Mark the pipe at the exact installation location. Follow the manufacturer’s instructions to ensure you cut away enough pipe to accommodate the filter and any connecting fittings. 
  • If your whole house water filter consists of two separate units—a pre-filter and a carbon filter— cut away a section of pipe that will account for two tees and a shut-off valve. Choose a length and configuration that is efficient for the space you’re working in. 
  • Clean the area of the pipe you plan to cut using emery cloth.  
  • Use a pipe cutter to make two cuts at the marks you made. Remove the section of pipe where the filter will be placed. Have a bucket placed underneath the location to catch any water remaining in the water line. 
  • Remove burrs on the cut pipe with a reamer or deburring tool
3
Install the Tees and a By-Pass Shut-off Valve
A person installing a shut-off valve to whole house water filter.

Whole house water filtration systems are equipped with filters that need to be changed from time to time. Depending upon the model you’re installing and your water supply, the pre-filter may need to be replaced every 6-months or so. The carbon filter will last much longer – up to several years in some cases. To make changing whole house water filters easy, install shut-off valves to isolate the units and a by-pass valve to allow the water system to be used when the filters are being changed.


  • If installing a unit with a pre-filter, install a copper tee on each side of the cut section of pipe.  
  • Connect them in between with pipe and a ball-valve.  
  • Dry-fit the sections to ensure they fit. 
  • If the unit you’re installing does not have a pre-filter, continue to step 4. 
4
Add Two Shut-Off Valves
A shut-off valve connecting pex tubing and copper tubing.
  • If installing a single unit without a pre-filter, add a ball-valve to either side of the pipe and the necessary fittings to connect to the filter unit. Dry-fit everything first. 
  • If installing a pre-filter and carbon filter setup, mount the units as instructed by the manufacturer’s instructions. 
  • Continue to pipe the tees to the filters, adding ball-valves between each tee and the filter.  
  • Finally, continue to pipe the necessary fittings to the respective filters.  
  • Dry-fit everything. 
  • Once everything is hooked up, the by-pass valve will remain closed, and the two valves feeding the filters will remain open. If the system becomes clogged and impedes water flow or when the filters need to be replaced, simply close the two valves and open the by-pass valve. 
5
Solder the Connections
A person soldering a connection on a copper pipe.
  • Clean and deburr the copper lines using emery cloth and a deburring tool. 
  • Clean the inside of the fittings with emery cloth or a fitting brush. 
  • Apply flux to the inside of the fittings and the copper pipe. 
  • Heat the fitting using a propane torch, filling the joint with solder when it is hot enough to melt the solder. Wipe the joint clean once the solder is applied.  
  • Solder fittings before attaching them to the filters so the heat of the torch won’t damage any internal water filtration parts
  • Apply thread seal tape to any threaded fittings and thread into the filter valve as instructed in the manual. Don’t overtighten. 
6
Add a Grounding Jumper Cable if Needed
A whole house water filter attached to copper water supply pipes.
  • This step in how to install a water filter is necessary only if you have copper or galvanized water pipes.  
  • Some older homes use metal water pipes as the electrical ground for the electrical system. Determine if your electrical panel has its ground wire attached to your water supply pipe. Look for a ground clamp and a wire attached to it coming from the panel box. 
  • If the ground wire is attached to the pipe, the water filter housing might have broken this ground path. Install appropriate grounding clamps to the metal pipe on either side of the filter. Secure a length of heavy-gauge copper wire across the filter from clamp to clamp and secure tightly. 

DIYers with a moderate amount of plumbing experience can learn how to install a whole house water filter. If you'd rather leave whole house water filter installation to a professional, consider using The Home Depot’s water treatment services


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