If you receive an error message similar to this:
Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
Each website has its own db connection pool which you can control through your web.config. If you are seeing a message similar to above you are leaking connections. You can read more about this here: http://www.15seconds.com/issue/040830.htm