One thing I don't remember seeing in the EERM: you should be able to see a list of sampling results and be able to identify the water source - like knowing that moderate to high levels of fecal coliforms and turbidity indicate surface water while groundwater has moderate to high levels of dissolved solids. Sort of like being given the chart in question 119 on the 2011 NCEES practice exam, but asking you to analyze the water source. I used the NC State review DVDs for this, and it was also covered in one of my college textbooks, Unit Operations and Processes in Environmental Engineering.
I don't think the EERM would be sufficient for sizing reservoirs, calculating hardness, or even sizing water treatment systems. I really relied on the review course for my water references.