An RV has storage or holding tanks for three types of water: Fresh water, grey water and black water. Fresh water is used for cooking, drinking, showering and flushing the toilet. The grey water tank collects the wastewater from the sink and shower (appropriately named as the water looks grey) and the black water tank collects wastewater from the toilet.
Freshwater tanks should be sanitized regularly following the RV manual instructions and grey water and black water tanks should be emptied at sani-dump stations (found at most campgrounds, some highway rest stops and truck stops, and in municipal areas). Most RV companies recommend emptying the black and grey tanks when they are at least 2/3rds full to better ‘flush out’ any deposits and eliminate build-up.
