Here are a few web sites to help you find a place to dump (and find water). Finding a dump is usually the more important issue for us. Getting water with the bladder is usually easier as all we need is a hose bib. We don't have to move the RV to the water source.
http://www.sanidumps.com/sanidumps_usamerica.php
http://www.rvdumps.com/dumpstations/
http://www.rvthereyet.cc/rvdumps.php/AL
We just used the Sanidumps site last week to locate a dump station when we were dry camping in Tucson. It worked very well for us.