Local campgrounds often have dump stations that you can use free of charge. In other cases you may need to find a local RV park and pay a nominal fee to dump. State parks are usually a good place to find facilities but usually you have to pay a "day use" fee for the privilege but this is seldom more than a buck or two. As a last resort we might have to travel to a nearby municipality and use facilities at their sewage plant but these instances are quite rare for me.
2011 F-150 HD Ecoboost 3.5 V6. 2550 payload, 17,100 GCVWR -
2004 F-150 HD (Traded after 80,000 towing miles)
2007 Rockwood 8314SS 34' travel trailer
US Govt survey shows three out of four people make up 75% of the total population