By dry well I assume you mean french drain. It's normally dry except when water is channeled into it. It's really just a collection point.
One last thought. Be sure that your gutters don't leak. Be sure you have working downspouts. And be sure you're dumping your gutter water at least 3' from the foundation of your home. Next to sloping issues, these are the most prevelant sources of water in basements and crawlspaces. The best time to check them all is in a rain storm.
Good luck! And hope all this helps.
PS: There are lots of sites on the WEB that talk about french drains (or dry wells). Go to your favorite Search Engine and put in some key words and search. If you don't know how to do this, find someone who does and buy them some beers to show you. It's worth it!