Abstract: A membrane filtration system which uses pump speed controllers to control flow rate and pressure during both the filtration cycle and the backwash cycle. The pump speed controllers operate by changing the frequency of AC current delivered to the pump motors, which changes the flow rate by changing the speed of the pump motor. The speed controllers operate by modulating the pump input power frequency in response to a signal from a flow or pressure signal received from a flow or pressure meter located on a liquid input pipe. This pump speed control method avoids the cyclical dampening patterns observed when trying to adjust pressure and/or flow rates by adjusting regulating valves. The system can also reduce or prevent formation of pressure spikes when switching from a filtration cycle to a backwash cycle, and vice versa. This reduces the likelihood of damage to the membrane from hydraulic pressure pulses.