Getting the line flowing
The immediate job is relieving the backup through a clean-out so waste water stops entering the house. That is the emergency part and it is usually what the first visit is about.
When waste water comes back into the house, the problem is usually the main line rather than one fixture. An independent plumber can get the line flowing, put a camera down it and show you what is actually wrong.
Two things cause most of these calls locally. Tree roots find the moisture at a joint and grow into it, then catch everything that passes. And the same expansive clay that moves foundations moves buried pipe, leaving a sag that holds water and collects solids.

A backup needs to be dealt with now; the reason for it needs to be understood before you spend money on the pipe. It helps to treat those as two separate conversations.
The immediate job is relieving the backup through a clean-out so waste water stops entering the house. That is the emergency part and it is usually what the first visit is about.
Once the line is open, a camera shows whether it is roots at a joint, a collapsed or cracked section, a sag holding water, or a blockage that will not return. You should be shown what it found.
Cutting roots, a spot repair at one joint or replacing a length of line are very different jobs. The quote should say which sections are affected, where digging is needed and what happens to the yard or driveway.
Clearing roots buys time, but roots come back to the same joint, so on a line that has backed up repeatedly the honest question is whether that section should be repaired or replaced rather than cleared again next season.
Older neighborhoods around downtown McKinney can still have cast iron or clay drain lines, where the failures tend to be corrosion, cracked joints and root intrusion. Newer subdivisions have plastic lines that rarely corrode but are perfectly capable of settling into a low spot as the clay under them moves.
If only one fixture is affected, drain cleaning is the right service, and our guide on telling a clog from a sewer line problem explains how to tell them apart. When a water line rather than a drain is the issue, see slab leak repair or our repair versus replacement guide if the heater is involved.
How far along the line the fault sits, how deep the pipe is and what is above it. A repair under a lawn is very different from one under a driveway. Ask the independent plumber to inspect with a camera first so the quote matches the actual problem.
Treat it as one. Keep children and pets away, do not run more water into the system, and avoid handling contaminated items without gloves. Ventilate the area and leave the cleanup of heavily affected rooms to people equipped for it.
Frequently. Roots follow moisture to a joint or crack, work in and then trap paper and grease. Mature trees near the line between the house and the street are the usual source, and a camera shows exactly where they got in.
Stop using water anywhere in the house, including dishwashers and washing machines, because everything you run drains into the same blocked line. If you have an outside clean-out cap, mention where it is when you call.
Call and describe the problem to be connected with an independent plumber.