The ESDI model 250 low-cost reverse osmosis (RO) controller board is a new controller from Electronic Systems Design Inc. that works with both low-pressure RO systems that operate off the municipal water main's pressure and high-pressure RO systems using an additional water pump. The controller incorporates several automatic flush cycles, and the individual selector switches allow the user to select flush times and frequency. It also features an input for monitoring and maintaining the level inside a storage tank as well as a lockout input for disabling the controller when necessary. Electronic Systems Design Inc., Card No. 289