I do not really think of my drains. I really don't even think a lot of people make it happen either. Normally, I think the one time people think about their drains is the place they start having issues. More often than not, which means the drains are clogged. Depending on which drain as well as the kind of clog, I may be able to repair it. However, if it's serious a treadmill from the major drains attached with home, then I will want to look in to a drain clearing service.
For minor clogs in indoor drains, I know about the old standbys like vinegar, fresh lemon juice, etc. These are all okay for small clogs in small drains such as the one from the bathroom or the one in your kitchen. Major clogs like matted hair or thick soap scum, something stuck deep inside the pipes, and even issues with an attached external drain will not be solved with your household methods.
This is the time I'd personally look into the professional clearing services. They've techs with long snakes and all sorts of safe chemicals to have stuff moving again. In some serious clogs, they own to dig down the location where the pipe is always to remove it, but there are many that can achieve that without building a mess. I suggest people use these services as opposed to destroying their piping trying to cut costs and performing it themselves.