Here's a pair of KM macros for use with the Stream Deck official plugin, with beautiful icons from Apple's SF Symbols:
Water Reminder Macros.kmmacros (58.8 KB)
One macro triggers a reminder every 20 minutes, by playing a sound and reversing the colours in the button:
Tip: find an interesting sound like this one in Freesound.
The other macro clears the alert when the button is pushed:
I hope you enjoy and stay hydrated!