I’ve heard recently that the problem with drinking a lot of water before a meal is that it dilutes the acid in your stomach so food doesn’t digest properly. That its best to drink an hour or so after a meal so as to give your food time to digest.
may not be true but sounds sensible on its face.
One purpose for drinking the water before a meal is that for some people thirst is misinterpreted as hunger. If you check the color of your pee, you can see if it is bright yellow or darker which means you definitely should drink the water immediately. You can also drink the water and then wait a half hour to eat. You may find you desire less food. Good for weight loss. If you are really having a hard time digesting or absorbing calcium, you can mix a little apple cider vinegar (tablespoon or 2) with water and drink that too.