What to know before calling a drain cleaning service

Before calling anyone, it helps to understand the various technologies that experts use to clear your sewer of obstructions. Some you can even do yourself.
Slow or non-functioning drains are the epitome of frustration for homeowners. For one thing, finding the clogs can be difficult, especially if you don't understand how pipes inside your home work. But if you've determined that your sewer is clogged between your house and the main sewer, it might require professional attention.
If you're handy
For less than $300 a day, you can rent a power auger, the sort of electric motor-driven cable snake that professionals use. Wearing sturdy gloves, feed the pedal-operated, spinning cable — upon which you attach a size-ascending range of cutting tools — through a clean-out opening and into the sewer. When you hit blockages, gently push the snake back and forth. Periodically run hot water into the drain to clean away chopped debris. This is a procedure you might consider doing annually, to avoid sewer failure in the first place.
Call the professionals
If you're afraid of spinning machinery, or (with reason) accidentally breaking an old pipe, it's time to bring in the experts. There are two basic drain-cleaning technologies that pros in the so-called "rooter" business use: the spinning auger just mentioned, or high-pressure water jetting. The former is best for clearing minor tree root issues. The latter is preferred for thoroughly reducing the ordinary grease and muck which builds up in all sewage pipes. (There is also a do-it-yourself option of using specialized jet attachments with a household pressure washer, but that's a task not recommended for the novice or anyone who wishes to avoid flooding the basement.)
Get several quotes
Not all drain doctors are created equal. Ask around among neighbours and check online for ratings of your local service providers. Obviously you'd prefer companies that have been at it for a long time, not some newcomer who's just renting the same device you could have used. Also, beware of anyone who gives you a quote before examining your particular drain situation. A minimum service charge is unavoidable, but nobody wants to pay $500 for someone who delivers only 15 minutes worth of work.
Look deeper into drain problems
If visits from the de-clogger have become too common at your place, there's one other drain-related service you may wish to consider —video inspection. It involves running a light/camera apparatus into the pipe, and creating a video record of the state of the pipe and where, exactly, clogging sites are located. Armed with a concrete vision of what you're dealing with, future interventions will be much less daunting.