💡 How To Deep Clean Your RV Black Water Holding Tank 💡 Deep cleaning your RV black water tank is simple and straightforward, making regular maintenance easy to perform. 🙌🚽 🛠️ What you’ll need: fresh water, Unique Clean-It, and time Steps: 1️⃣ Close your black tank valve. 2️⃣ Fill your black tank completely with fresh water. (Cleaning only happens where water touches… fill it up!) 3️⃣ Pour one full bottle of Unique Clean-It into your 40 gallon black tank. (No amount of Clean-It is too much.)