I was diagnosed with Stage 4 CKD due to severe oxylate damage four years ago. My GFR was 16 and Creatinine 3.80. Through diet and increased hydration, I’m now at 36.7 and Creatinine of 1.90. Everyone’s situation is different but…..My experience with hydration is too much can be a bad thing. I was initially advised to drink 4L/day. Then we found my sodium levels became too diluted. So, I’m now drinking 3L/day. For my low oxylate diet, I use this study as a guide - https://kidneystones.uchicago.edu/how-to-eat-a-low-oxalate-diet/