Kitchen sink clogs in Denver are usually grease, food and soap scum, sometimes with a partial main-line problem behind them. Chemical drain cleaners do not dissolve grease buildup properly, and they are a hazard for anyone who later opens the trap. These are the chemical-free steps that actually work, in order.
Start with a plunger
Block the second basin first
Use a cup plunger, not a flange plunger. Block the second basin of a double sink and the overflow, if there is one, with a wet rag so the pressure goes down the drain. Make sure there is enough water in the sink to cover the plunger cup, then plunge firmly for 15 to 20 seconds. Often that is enough for a soft grease clog near the trap.
Clean the trap
Bucket under the trap
If plunging does not work, the clog is probably in the p-trap. Put a bucket under it, unscrew the slip nuts by hand or with channel-lock pliers, and empty the trap. Clean out the grease and food, check the trap arm into the wall, and reassemble, making sure the washers sit straight. Run water and check for leaks at both slip nuts.
Boiling water and dish soap
For a grease clog, a kettle of boiling water poured slowly down the drain, preceded by a squirt of dish soap, can melt and move a soft blockage. This helps with grease only. It does nothing for roots, scale, a belly in the line, or a collapsed pipe, and it will not help if the clog is past the trap in the main line.
What not to do
Do not pour chemical drain cleaner down the sink. It does not clear roots or scale, it can damage older pipes, and it leaves a caustic residue in the trap for the next person who opens it. Do not use a drain snake blindly in a kitchen line without knowing where the clog is: a snake can damage a trap or push a clog further down.
When it is not the kitchen sink
If more than one fixture is slow, if water comes up in the other basin or the dishwasher, or if the same sink clogs again within weeks, the problem is past the trap, in the branch or the main line. That needs a camera inspection to find the cause. See drain cleaning, sewer camera inspection and why your drain keeps clogging after cleaning. Call (720) 599-7253 if the steps above do not clear it.