The Reverse Osmosis water is not really harmful for your health however drinking Reverse Osmosis water doesn't really provide the natural health benefits of water that hasn't been through the Reverse Osmosis process.
Water contains natural minerals, Calcium and Minerals that are needed to keep the body healthy and the Reverse Osmosis water doesn't contain those natural needed things so your health doesn't benefit from the Reverse Osmosis water.
So while drinking Reverse Osmosis won't actually harm your health it won't improve your health when drinking it.
If you want to get the health benefits of water you should drink regular tap water that is more healthy for you.