How to Clean Out the Main Drain Properly

If water still backs up in your home even if you have cleaned the most likely clog sites in a home, the main drain—which leads from the home to the sewer system of the city—might be clogged. If you believe that tree roots caused the main drain to clog, then there is nothing you can do but contact a plumber to check and fix it for you. However, if there are no trees around you and you know that a lot of debris has been dropped down the drains in your home in the past, you may be able to clear the main drain yourself. Here’s how:

1. Find the clean-out ports of the main drain. These ports are short and stubby tubes which branch off the pipes of the main drain at an angle shaped like the letter Y, fitting with a cap (plastic or steel) which has a square-shaped fitting on its top, and can be found in the crawl space or basement. A few houses may have these outside (along the foundation of the property), the garage, or the pantry. Follow all exposed drain pipes until you have sight of them.

2. Prepare a waste bucket for use in catching overflow from the primary drain cleanout. Spread tarp or plastic sheeting around the main drain so overflow is contained.

3. Get a pipe wrench and use it in loosening the cap of the clean-out. Any backed-up water will most likely flow out once you open it, so it makes sense to loosen it slowly. Once water stops, take the cap out.

4. Have the head of a power snake inserted through the clean-out of the primary drain and into the primary drainpipe. Make sure that it is fed as far as possible until it gets stuck somewhere. Resistance is a sign of a clog.

5. When you operate the power snake, make sure that you follow the instructions of the manufacturer. The vibration should be felt as it cuts the clog.

6. Continue to feed the feed the drain snake into the pipe so more clogs can be cut. Then pull the cable back into the primary pipe, making sure that it is fed to the primary pipe by the opposite direction. Cut any clogs you encounter.

7. Put the cap back on the cleanout of the drain. Ensure that it is tightly sealed.

8. Head to a toilet and flush it many times to check and ensure that the system is completely free of any clogs.