There are two ways to log water on your daily log.
Option 1: From the Water metric
Ensure that Water is displayed on your daily log
Go to Profile > Nutrient Settings
Enable "Show Water" as one of you four optional metrics to display on your daily log
On your daily log, tap the Water metric
Enter the water you consumed and tap the check mark when done.
Option 2: From the ... menu in the top right corner
If you don't want to display water consumed on your daily log but you do want to record water, then:
On your daily log, tap the ... button in the top right corner
Tap "Log Water"
Enter the water you consumed and tap the check mark when done.
Note: Currently you can only add water to your daily intake but not take water away. For example, if you make a typo and enter 120 oz of water instead of 12 oz, there is no way for you to correct that error on your own. This is something we'll be fixing soon but for now just email hello@macrosfirst.com if you need help correcting a water entry.