The same things happens to me! / happening to me right now haha. It helped when I put chlorophyll in my water, only a couple drops will do it. Tap water / any water isn't always neutral, the pH can at times be off balance and on the acidic side (I also have GERD) and chlorophyll is a great alklanizer (as in in makes the water closer to a base than an acid). SO, try water with liquid chlorophyll in it (you can buy it at your local nutrition store, make sure its unflavoured otherwise those with GERD will also have a bad reaction to it because it is normally flavoured with mint).
When drinking water from anywhere, tap, work, bottled, filtered, cold, hot, I always have a bad reaction. After adding liquid chlorophyll I have no complaints and no problems at all