It is not recommended and would not likely work. If the solenoid fails and they often do, your house and tank would be flooded. The osmolator would only allow the solenoid to be open 10 minutes which is not enough time in many cases and the water quality would be poor as the salts removed by reverse osmosis would diffuse back across the membrane during the off cycle. I personally had a solenoid jam with a small amount of sand from our municipal water and fail. I spent thanksgiving weekend repairing my wood floor, never rely on a solenoid valve. My new set up will have an emergency overflow drain. I use the 8555 to top off my reservoir and the 3155 osmolator to top off the tank from the reservoir. My problem was I did not follow the instructions which specify having the drain on the reservoir in case the solenoid fails.