Definition of rappel for English Language Learners : to move down a steep cliff, rock, etc., by pushing your feet against its surface and sliding down a rope RAPPEL Defined for Kids
How much water you need to drink to get the most benefits depends on your diet, exercise routine, health and weather. You can start by aiming for the basic recommended amount for adults, which is 8 to 12 cups a day, according to Clemson Cooperative Extension, and making adjustments as needed.
The NHS has detailed how much water we should be drinking on their website: The European Food Safety Authority recommends that women should drink about 1.6 litres of fluid and men should drink about 2.0 litres of fluid per day. That's about eight glasses of 200ml each for a woman, and 10 glasses of 200ml each for a man.