Belmont is home to the Belknap Mill, one of the region's oldest textile mills (it now includes a museum devoted to the manufacturing history of the area). Between enjoying the local hiking and swimming opportunities, and emptying your tanks at the nearby dump stations, visit the Tilton Memorial Arch, Smith Meeting House and Canterbury Shaker Village.
Dump stations have a drain cap that covers the sewer and drain outlet. You need to close the valve on the tank, take the cap off the sewer and push the hose from your tank into the outlet. Once you turn the valve, the tank will empty the blackwater.
You should empty the tank when it reaches 2/3 capacity. If it goes any higher, it can overflow.
Dump stations generally charge users for their services. Some campground stations offer this service for free if you spend the night there.
A RV dump station is a facility that lets you empty your holding tanks without getting your hands dirty. It also uses sanitary methods to dispose of the waste.