How to prevent unwanted black tank odors

Keep odors from your black tank from permeating your campsite by leaving the dump valve closed until you are ready to dump--even when hooked up--and not until the tank is at least half full (a fuller tank will dump more powerfully than a partial tank). Dump your black tank, then your gray tank (which should be kept closed also) so the gray water will wash out your dump hose. Install a venturi sewer vent to suck away odors from the black tank while parked.