Clearing the line properly
The blockage is removed mechanically through a clean-out or the fixture itself rather than pushed further down the pipe. Chemicals are not the tool for this, and they make the line unpleasant and unsafe to open.
A sink that empties slowly, a tub that stands full or a kitchen line that blocks every few weeks. An independent plumber can clear the drain and then explain what the pipe itself looks like, so you know whether it will come back.
That last one changes the job. A single slow drain is usually a local blockage in that branch. When several fixtures slow together, or the lowest drain in the house backs up, the problem is more likely to be the main line rather than the trap under the sink.

Clearing the blockage is the easy part. The useful part is understanding why that drain filled up, which is what stops you paying for the same visit again in a month.
The blockage is removed mechanically through a clean-out or the fixture itself rather than pushed further down the pipe. Chemicals are not the tool for this, and they make the line unpleasant and unsafe to open.
Grease and food waste behave differently from paper, wipes or hair, and repeat blockages in the same spot often point at the pipe's slope or condition rather than at what went down it.
Once the line is open, water should run long enough to be sure it stays open, then the fixtures sharing that branch are checked. Ask what came out and what was seen.
For most kitchen and bathroom blockages, clearing the line is the whole job. When a drain has blocked three or four times in a year, the better question is what is wrong with the pipe, and that is worth investigating before spending again on another clearing.
Older McKinney houses near the square, and other homes built before the 1980s, can still have cast-iron drain lines that have roughened or scaled on the inside. Newer slab homes are usually plastic, but a poorly sloped run laid during construction causes the same repeat blockages.
If the whole house is affected rather than one fixture, start with sewer line repair and read our guide on telling a clog from a sewer line problem. Where water is appearing but no fixture is blocked, leak detection is the right first step. A kitchen line that only backs up while the disposal runs is worth looking at as garbage disposal repair first. You can also see how calling works.
How the line is reached and how far in the blockage sits. A sink cleared through the trap is straightforward; a main line reached through a clean-out in the yard is a bigger job. Ask the provider for the price once it is clear which one it is.
It is better not to. It often sits in the trap without clearing anything, it can damage older pipes and it makes the line hazardous for whoever opens it next. A plunger is fine; beyond that, call.
Repeat blockages in one spot usually mean the pipe is the problem, not the habits of the house. A rough or scaled interior, a sag that holds water or roots at a joint will all catch debris again. A camera inspection settles it.
Call and describe the problem to be connected with an independent plumber.