Caravans or RVs here in the USA typically have a drain that must be hooked up to a dump station. At RV parks, a service will sometimes come around and suck out the poop tank. Otherwise, you go to a dump station, hook one end of your hose to the RV drain and the other to the dump station's tank. Usually uneventful and not too smelly -- unless the hose comes off in mid-dump! You know how I know that?!!