A whole-house sediment filter looks like a simple job: a housing, a cartridge, and a few connections on the main line. The install itself is where most problems start, though, because the order of the steps decides whether the house ends up with a leak, trapped air, or a filter that can be bypassed when it should not be. Knowing the sequence lets you check the crew's work as it happens instead of finding out later.
Before the crew arrives
Clear a path to the main shutoff and to the spot where the filter will mount. Move stored items off the wall and floor. Ask the installer to confirm the mounting location and the connection point on the main line, and to tell you whether the work will shut off water to the whole house. Plan for a period with no water, and make sure everyone in the home knows it is coming.
Shutoff and relief
The crew should close the main shutoff, then open a few taps at different heights so the line drains and the pressure drops before any cutting starts. If they skip this step, expect water in the work area and a wet floor. Ask them to show you that the supply side is dry before they cut.
Cut, fit, and mount
The installer cuts the line at the chosen point, adds fittings, and mounts the housing to the wall or a framing member. The housing should sit upright, with room under it to remove the cartridge without straining the connections. Check that the bracket is fastened into solid material, not just drywall. A housing that moves when you lean on it will move again under pressure.
Bypass and connections
A bypass valve lets the house run without the filter during service. Ask the crew to show you the bypass handle and which position means filtered water and which means bypass. Confirm that the connections are tightened and that the fittings match the pipe material in the wall.
Slow restore and pressure check
Water should go back on slowly, with the taps open so trapped air can escape. The installer should watch each joint for drips while pressure builds. A joint that seeps on the first restore is far easier to fix before the crew leaves than after they are gone.
Purge the line
Run cold taps for a set period to clear air and any loose carbon fines from new cartridges. Cloudy water at first is normal, but it should clear. Ask what the crew expects to see and how long they expect it to take. If the water stays cloudy, the crew should check the cartridge and the connections before leaving.
What to ask before the crew packs up
Ask the installer to walk you through the bypass position, the cartridge location, and the shutoff for the filter alone. Ask what you should watch for in the first week. Write down the answers, because you will need them when a question comes up later.