EDI modules are rated for specific flowrates. Each module in a system can handle a maximum and a minimum amount of flow. If the product flowrate of the RO falls within the specified limits of the EDI modules, there should be no need for feed flow control to the EDI module. The only flow control required is the reject flow.

Adjustment of the reject flow should be set based on the product quality of the RO and should require very little adjustment. The reject flow is typically set at 10% of the feed flowrate. It is important to note here that the quality of the RO design will play an important factor in the way the EDI operates. A poorly designed RO that has constant product quality fluctuations will cause upsets in the EDI system and will make the EDI difficult to control.