Just got an email with this website - thought my RV friends might like it if you don't already now about it:
RV Dump Stations
Not a week goes by without a customer asking where the nearest facility is to evacuate the holding tanks on their RV. The need for a dump station is as inevitable for RVers as death and taxes are for everyone.
Though we are able to point people to those facilities near our stores, once out of the area, we haven't been of much help - until now. Needless to say, there isn't much you can't find on the Internet and this topic is no different.
While traveling throughout the US and Canada, a couple clicks of the mouse can tell you where the nearest dump facility can be located, what hours they are available, what the cost is, and perhaps even any hazards, like low hanging trees, that might affect the access.
This one stop source is simply named rvdumps.com. It even allows registered users to add comments about existing sites and to add sites that aren't currently listed on the site. It is smartly organized by state and then by Interstate or Highway. To further simplify the process there is a search feature that allows you to enter key words like the name of a town or a facility name.
This site is easy to use and would be a good one to add to your favorites if you bring a laptop or on your tablet or smart phone. Or, simply visit the site with your itinerary in mind and print out a list covering your route. And, be sure to add any places you find to help your fellow RVers in their time of need.