It depends where its coming from. You can try closing your drains when not in use to see if that alleviates the problem. You can also try putting baking soda down the drains periodically.
The first thing that you need to do is to find out the cause and source of the smell. There may be a break in a pipe or a leakage in the drain, once you have found out the cause, then you can find an easy solution.
