What should I check first for a kitchen faucet base leak?

[Adam.L]

My kitchen faucet has started leaking right at the base where it meets the countertop, and I can't seem to get it to stop. I tightened the mounting nut underneath with a basin wrench, but after a day or two the slow drip comes back. I'm wondering if the issue is with the gasket or if I need to replace the entire cartridge.

[GaryG]

I had a similar drip at the base once. I thought tightening the nut would fix it, but it kept coming back. For me it ended up being a tiny rubber seal under the collar that gave way, not the main cartridge. Replacing that little piece made a difference for a while.

[Ethan_R]

In another case I suspected the cartridge after the drip persisted. I swapped the cartridge and the leak stopped for a bit, but it came back later, so I’m not sure if that was the root cause or just bought time.

[James_J]

If the leak is right at the base, check the gasket under the deck too. Sometimes the counter or mounting ring leaks even when the visible parts stay dry.

[EleanorLT]

I’d still wonder if the base seal is the real culprit rather than the cartridge; do you hear the faucet drip right after you run it, or only after it sits?