In Ayurveda one of the terms used is Agni, which refers to the “digestive fire”. It is really likened to an elemental force of fire that not only breaks down our food, but aids in spreading warmth to the rest of the body.
Of course it is not actual fire, but a metaphor.
Yet in the West, ice water is commonly drunk, especially with meals. This is a good idea…IF you want to impair your digestion. The constricting force of the cold water is going to halt some of the action.
In fact lots of water should not be drunk around meals period. Small sips are okay, but too much would serve to dilute your gastric juices.
On the flip side, warm or hot liquids can be helpful. If the water is the same temperature as your body, not energy needs to be expended by your body to warm it up.
A simple experiment you can try is to drink a glass of water at different temperatures and notice the effects. It will be subtle but you should be able to notice the difference between ice cold water, room temp water, and hot water pretty easily.
And having warm water as a delivery vehicle for herbs can help your body to better absorb and circulate them. This is a simple energetic method. Each herb may be hot or cold, warm or cool, and thus these energetics can be balanced or amplified depending on what you take them with.