@TME600, your situation and experience sounds a lot like mine. I took WRE because of my background in stormwater, but I had no experience in wastewater collection, water treatment and water quality which made up a significant portion of the WRE depth. Even in realizing this, I didn't really put time in studying or doing practice problems in wastewater, water treatment, or water quality, nor did I have a structured study plan. Instead I thought spending my preparation time by doing random practice problems in the subject areas in the morning and stormwater in the afternoon would be sufficient enough to make up for my deficiencies in the other areas and probably (barely) get me by. Needless to say, I failed the first time I took the exam and diagnostics showed I performed almost as expected in all subject areas, with the exception of soils and structures which I under-performed and probably was the difference in me passing and failing.
So the second time I prepared for the exam, I elected again not to do a review course and instead just develop my own structured study plan and stuck to it for the most part. I wouldn't discourage anyone from doing a review course or necessarily recommend one, but what think you need to have regardless is a focused and structured study plan which many of the review courses provide you. However, if you elected not to do a review course, I think you would okay as long as you've identified the subject areas you're deficient in and spend time reinforcing your knowledge or in my case, actually learning the content for the first time. And my study plan primarily consisted of me spending days at a time in specific subject areas, primarily working through problems (untimed) and reading information from my resources as I came across problems I wasn't as familiar. And once a week, I would spend about 2-3 hours doing timed practice problems.
Also, I didn't have any wastewater or water treatment specific references the first time I took the exam. However, right after I signed up to take the exam the 2nd time, I purchased 3 reference books I thought were pretty helpful. 1) Water & Wastewater Calculations Manual by Shun Dar Lin, Water & Wastewater Engineering - Design Principles and Practice by Mackenzie Davis, and a dictionary of Civil, Water Resources & Environmental Engineering by Harry Friebel. I also found a lot of useful formula sheets for wastewater and water treatment online and added to my "go-to-binder". I think a combination of this and the focused studying paid off because I passed the 2nd time and actually felt pretty confident leaving the exam that I had passed.
But you seem to have the right attitude and I think you'll do fine on the retake. I'm more than happy to answer any specific questions you may have with my overall preparation.
