Do I Install a Water Filter Before or After the Softener?

Contact the local building permits office. While homeowners can do their own plumbing work, a permit and inspections may be required.

Locate the main water line going into the house. Determine if the line contains a 3/4-inch or 1-inch pipe.

Research and select a whole house water filtration system that removes the salts, chemicals and sediments of most concern to you. For example, you may be very worried about the chlorine and fluoride in city water. If you have well water, then bacteria, sediments and nitrites may be your main concerns.

Turn the water off at the main shut-off valve or at the meter. Open several cold water faucets to drain the water system.

Install the water filter according to the manufacturer's directions. While instructions may vary, in general the filter is mounted in a convenient location near the water softener where you can easily change the filter.

Turn the water on slowly while a helper watches for leaks. Once you're sure that there are no leaks, turn on the closest cold water faucet for 15 minutes. This will activate the filter.