How to Diagnose a Kitchen Faucet Problem
Faucet problems usually give you warning signs. A drip you hear at night. A handle that takes more effort than it used to. Pressure that was fine in January and is now half of what it was. None of it happens suddenly, which is why most people put off dealing with it longer than they should.
Part of the reason for that delay is the quality of advice available online. Most repair guides tell you to "check the cartridge" without explaining what a cartridge is, where it is located, or how to tell whether the cartridge is actually the problem. You end up reading several articles, possibly buying the wrong part, and still not knowing whether this is a job you can do yourself in an hour or whether you need to call someone.
The tool above is designed to cut through that. Three questions, a specific answer. You get the most likely cause, the steps to fix it, and which parts to look for. It covers 24 combinations because the symptom by itself is rarely enough to tell you what went wrong.
Where it leaks matters more than that it leaks
Most people describe the problem as "it's leaking" and leave it there. But water dripping from the tip of the spout when the faucet is off is a completely different problem from water pooling at the base of the spout. The first is almost always the cartridge. The second is almost always O-rings. Both get called a leak, but they need different parts and different steps to fix.
The same logic applies to low pressure. Both sides weak at the same time points to the aerator, the small threaded screen on the spout tip that fills with mineral scale over time. One side weak on its own usually points to a partially closed shut-off valve under the sink, which is not a faucet problem at all. That valve check costs nothing and takes ten seconds. Most generic guides skip it entirely.
Faucet age changes what makes financial sense
A cartridge replacement on a three-year-old faucet is almost always the right move. On a faucet that is 12 or 15 years old, it is worth pausing before ordering parts. Cartridges for older or discontinued models can be expensive and hard to find. A solid mid-range faucet from Delta, Moen, or Kohler runs $80 to $150 and typically includes a lifetime warranty that covers future parts at no charge. That warranty matters: the next cartridge, the next set of O-rings, the next aerator, all free. On a faucet that has already needed one repair, that math is worth running.
The diagnostic tool factors this in. If your faucet is 7 years old or older, the result gives you an honest look at whether the repair is worth it given part costs and how much useful life the faucet likely has left.
What the tool does not cover
It is built for problems that a careful homeowner can fix on a weekend with basic tools and a $10 to $30 part. That covers the majority of kitchen faucet issues. For anything structural, such as water under the floor, a burst supply line, or a shut-off valve that is fully seized, call a licensed plumber. The tool will tell you when that is the better path.