We know that Paul told Timothy to use a little wine for the sake of his stomach and his frequent ailments (see 1 Tim. 5:23).
Actually, Paul told Timothy to stop drinking water and to use a little wine for the sake of his stomach and frequent ailments. This would seem to indicate that something was wrong with the water. Obviously, if you are drinking contaminated water, you should stop drinking it and start drinking something else, or you will probably have stomach problems like Timothy.