Toilet Overflow

My toilet overflows when I run the water in my kitchen sink. I had a plumber come in and snake the main drain (under the toilet), but the problem still persists. What is causing the overflow? I first noticed this problem when we had heavy rainfall. I also noticed a foul odor coming from the bathroom. I called WSSC about that and they just recommended that I pour some bleach down the toilet once a month. Is there another solution to this particular problem? I know I am jumping around on this, but the overflow from my toilet has me concerned that a pipe might be loose or broken. Help!

Sewer or septic system? If it backs up during a rainstorm, that could be an issue.

Thanks for your response; this is a sewer system. What issue does this present?

Perhaps, my original posting was not that clear. I am having several problems with the bathroom on the first level of my home.

1. I noticed that during a heavy rain that the toilet seemed to overflow at the base, but am not sure that that was the reason.

2. I noticed that the overflow occurred from the base of the toilet when either the washing machine was on and going through its cycles and/or the use of the kitchen sink.

3. I smelled odors coming from the base of the toilet since it does not set flat on the floor. I was told that the reason the toilet is not setting flat on the floor is because the floor in the bathroom is uneven.

For problems #1 and 2, I had a plumber come over to snake the main drain. That did not solve the problem because as soon as I started using the kitchen sink, the toilet overflowed. The plumber has agreed to come back to snake the kitchen sink. As for problem #3, I need to know what can be done to seal the bottom of the toilet.

Way back when, almost all sewer systems combined both the water runoff from the roadways and the waste into one system. This meant that when it rained, they had to treat potentially a huge volume of water, most of it fairly clean. The EPA has been pushing local governments to split their sewers into runoff and waste systems. If yours has not been split, the main line could literally be full, so there's no place for your waste to go when there is a rainstorm. The only thing you can do about this is complain, and possibly (they often don't work well) put a check valve on our inlet to the sewer so that can't back up into the house. It will do nothing (except create problems if it gets clogged by itself) about your ability to send waste out, just prevent it from coming back. Sounds like you may need to discuss this with the locals to understand what's going on.

If this happens regardless of the recent rain volume, you have a clog in your lines getting to the sewer.