Two identical tanks are $3 \mathrm{ft}$ in diameter and $3 \mathrm{ft}$ high, and they are both vented to the atmosphere. The top of tank B is level with the bottom of tank A, and they are connected by a line from the bottom of A to the top of B with a valve in it. Initially A is full of water, and B is empty. The valve is opened for a short time, letting some of the water drain into B. An inverted manometer having an oil with $\mathrm{SG}=0.7$ is connected between taps on the bottom of each tank. The manometer reading is 6 in., and the oil/water interface in the leg connected to tank A is higher. What is the water level in each of the tanks?