Seltzer water can help some people when they have gas and for me drinking a bit of Seltzer water does relieve some of my gas buildup in my stomach.
But drinking too much Seltzer water may actually increase the gas in your stomach because of the carbonation.
When you do have gas buildup in your stomach it's best to drink some water to help relieve the gas buildup.
Also when eating foods make sure to eat more slowly to avoid sucking in air which is a cause of gas in your stomach.
When you eat too much food too fast then you can swallow in air which leads to gas in your stomach.
So take it more slowly when eating and also take some gas relieving supplements or something such as Beano which works for me.