Lemon Water is low in calories unlike some other drinks so it makes it a great drink to consume when trying to flatten your stomach and also for losing belly fat or losing weight in general.
The lemon water should be lemon juice from fresh squeezed lemons for the most health benefits and if you drink it daily and do some flat stomach exercises daily you should see a flatter stomach within a month or two.
Lemon Water is good for getting a flat stomach and losing weight but you also need to exercise because the lemon water alone won't give you enough results when trying to get a flat stomach.
But since lemon water is very low in calories it can help with flattening your stomach along with the flat stomach exercises.