Most Likely Causes (Ranked)
Kohler faucets use proprietary ceramic disc cartridges that vary by product line. The GP1016515 is common in kitchen models, while bathroom faucets may use the GP1017426 or others. After 5-10 years, the ceramic discs score from mineral particles and the internal seals harden. Unlike Moen's standardized approach, identifying the correct Kohler cartridge requires your specific model number.
Kohler deck-mount faucets use a gasket or plumber's putty between the faucet body and the sink deck. On their widespread models (separate handles and spout), each component has its own gasket. These compress and dry over time, allowing splash water to seep below the deck into the cabinet.
The brass valve seat inside the Kohler faucet body develops pitting from hard water minerals. A new cartridge can't seal against a damaged seat, causing the drip to return shortly after cartridge replacement. This is more common in areas with hard water (white scale on fixtures).
Water pressure above 80 PSI forces water past seals in any faucet, including high-quality Kohler models. The drip may appear only at night or during low-usage hours when municipal pressure peaks. A pressure gauge on a hose bib will confirm.
The braided supply lines connecting the shut-off valves to the Kohler faucet tailpieces degrade over 5-8 years. The connection at the faucet tailpiece can loosen from vibration. Water appears under the sink, not from the faucet spout.
How to Fix It
Replace the Kohler Cartridge
$40-80 DIY / $150-250 Pro- 1Turn off both shut-off valves under the sink. Open the faucet to drain.
- 2Remove the handle: Allen key (varies), Kohler valve tool (for some models), standard pliers.
- 3Find your model number (tag on supply hose, or Kohler.com model identifier tool). Order the specific cartridge. Remove handle (set screw location varies). Some Kohler models require a special bonnet nut wrench. Pull old cartridge, insert new one noting orientation.
- 4Test both hot and cold. If hot/cold are reversed, rotate the cartridge 180°.
- 5Pro tip: limited lifetime warranty on residential faucet cartridges — call before buying parts.
Replace O-Rings
$5-15 DIY- 1Turn off water. Remove the spout by pulling straight up or removing the set screw at the base.
- 2Note the O-ring sizes — Kohler O-ring kit: model-specific — search 'Kohler [model] repair kit'.
- 3Coat new O-rings with silicone plumber's grease before installing.
- 4Press the spout back into the body and test.
Tighten or Replace Supply Lines
$8-15- 1Check the supply line connections under the sink with a dry paper towel.
- 2Tighten loose connections a quarter turn. Don't overtighten.
- 3If the braided line is 5+ years old, replace it. Hand-tighten plus a quarter turn.
When to Call a Professional
Kohler cartridges are brand-specific — don't use universal replacements.
Don't force a stuck cartridge — you can crack the brass valve body. Use penetrating oil and patience.
If the faucet is 15+ years old and multiple parts are failing, replacing the entire faucet ($150-400) is more cost-effective.
Kohler uses many different cartridge designs across product lines (Simplice, Artifacts, Bellera, etc.), making it essential to identify the exact model before ordering parts. The model number is usually on a tag on the supply line or inside the cabinet.
How to Prevent It
Don't crank the handle — firm is enough. Overtightening destroys seals faster.
Clean the aerator every 6 months to prevent debris from reaching the cartridge.
Address drips immediately — a small drip indicates a seal that will only get worse.
Know your Kohler model number (tag on supply hose under sink) for ordering the right parts.
Frequently Asked Questions
Look for a model number on a tag attached to the supply hose under the sink. The Kohler logo is usually on the faucet body. You can also use Kohler's website to identify your model from a photo.
Repair if: it's under 10 years old and just needs a cartridge ($40-80). Replace if: it's 15+ years old, the valve body is corroded, or parts are discontinued.
5-10 years with normal use. Hard water, high pressure, and excessive handle force shorten cartridge life. Annual aerator cleaning prevents debris damage.
Yes — limited lifetime warranty on residential faucet cartridges. Contact them before buying any parts.