Guides · Install
How to Install a Faucet Filter
A ten-minute job in most kitchens — the three compatibility checks, the adapter rules, and when to stop and ask the landlord.
Check compatibility before you buy
The spout must have removable, threaded aerator threads. If the aerator is integrated, cache-style, or the faucet is a pull-out sprayer, most faucet-mount filters will not fit.
Look under the spout and photograph the thread. Adapter kits are keyed to thread size and pitch, and getting the wrong one is the usual reason a "universal" filter does not fit.
Check clearance: with the diverter attached, the spout must still clear the sink floor and any pot you fill.
Removing the aerator
Wrap the aerator in a cloth and turn it counter-clockwise by hand first. Use a pair of slip-joint pliers only if it is seized, and only through the cloth.
Soak the aerator in warm water with a little vinegar while you work — it removes the scale that made it stiff.
Keep the aerator and any washers in a labelled bag. You will want them when you move out.
Fitting the adapter
Thread the adapter on by hand until it is snug, then a quarter turn with the pliers at most. Plastic threads strip easily and a leaking adapter is worse than a loose one.
If the adapter bottoms out before it seals, you have the wrong size — do not force it with PTFE tape.
Attach the filter body to the adapter, then open the tap slowly and watch the joint for a full minute.
First run and leak check
Flush according to the manual before drinking. New carbon cartridges shed fines, and the manufacturer's flush step is usually 1–5 minutes of run-to-drain.
Check for weeping at the adapter and at the filter body with a dry tissue — a slow drip is easier to catch before it becomes a cabinet puddle.
Test the diverter in both positions. If unfiltered flow is weak, the diverter is not fully seated.
When to stop
Stop if the spout is not threaded, if the faucet is a pull-out, or if the only way to make the adapter fit is force.
Renters: a faucet-mount filter is reversible and leaves no trace, which is exactly why it is the standard answer. Anything that needs a hole or a shut-off valve belongs in a conversation with the landlord first.
If the existing shut-off valve under the sink will not close, do not proceed with any under-sink work until a plumber has looked at it.
FAQ
Quick answers
+Do all faucet filters fit all faucets?
No. "Universal" refers to the included adapter set, not to every spout. Threaded, removable aerators are the requirement, and pull-out sprayers generally are not compatible.
+Do I need to turn off the water to install one?
No. Faucet-mount filters attach to the spout with the tap closed, which is one reason they are renter-friendly.
+The filter leaks at the adapter — what now?
Check the adapter size and the rubber washer first. If it still weeps, the thread pitch does not match and you need the correct adapter rather than more tape.