This paper is the first part of a three-part session entitled “Guidance for Existing MF/UF Facilities: When is membrane replacement recommended, what are the viable options, can costs be reduced and performance improved”. The three-part session will provide current available options for Owners for replacement, retrofits, and an overview of open-platform membrane systems. In addition, the session will provide factors to consider when evaluating alternatives, and a case study which demonstrates implementation of a retrofit. The three parts are: Part 1 – Expanding MF/UF Plants – should you cut the cord with your existing manufacturer? Part 2 – Strategies and Options for Replacement of MF/UF Membranes and Upgrading Plant Performance Part 3 – Seeking a Better UF Procurement Mousetrap; A Case Study of Unique Procurement Approaches for Expansion of an Existing Horizontal UF WTP