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The Bottom Line
Most under-sink water filter installation takes 30-60 minutes with basic tools — adjustable wrench, screwdriver, maybe a drill if you need a new faucet hole. No plumbing license needed for a standard setup.
Under-sink water filter installation scares people off more than it should. Here’s the general process — exact steps vary by model, so always check your specific unit’s manual, but this covers what to expect.
Tools You’ll Likely Need
- Adjustable wrench
- Screwdriver
- Drill (only if adding a new dedicated faucet, which most kits include)
- Teflon tape for threaded connections
- A bucket or towel for the inevitable drips when disconnecting the water line
General Installation Steps
- Turn off the cold water supply valve under the sink.
- Drain the remaining water from the line by opening the faucet.
- Install the diverter valve or T-fitting onto the cold water line, following your kit’s instructions.
- Mount the filter housing/cartridge to the inside of the cabinet or base of the sink, wherever your kit specifies.
- If adding a dedicated faucet, drill the mounting hole (many sinks have a pre-cut hole for a soap dispenser you can repurpose) and install it.
- Connect all tubing per the kit’s diagram, double-checking each connection is snug.
- Turn the water supply back on slowly and check every connection for leaks before walking away.
- Run water through the new filter for several minutes before first use to flush out any loose carbon fines.
When You Should Call a Plumber Instead
- Your existing shutoff valve is old, corroded, or doesn’t fully close
- You’re not comfortable drilling into stone/granite countertops for a new faucet
- You’re installing a reverse osmosis system with a drain line tie-in (more involved than a standard filter)
- You’re on well water with unusual plumbing setups
Ready to pick a system before you install it? See our under-sink water filter buying guide for what to look for.