Get cleaner rainwater into your tank. Between downpours, dust, leaves and animal droppings can settle on your roof. When the rain returns, the first flush of water washes them off, and your first flush diverter sets it aside to keep it out of your tank. So only the cleaner water that follows is stored. Its large-diameter Max Chamber diverts more of that first flush in a shorter run of pipe, and the patented Catch-All Tee captures more of it than a basic tee.