I always feel super awkward taking a drink during a talk. I've taken practice to keenly watching for the moment a speaker takes that pause for a sip of water because it's something I still haven't figured out how to feel comfortable doing. I've seen many speakers who do this with grace and style.
In watching some of my own talks back, and also in seeing/attending a lot of talks, awkwardly taking a drink is way better than the weird sound a "dry mouth" can make through a microphone. A worse offense, in my opinion, is the jarringly amplified sound of repetitive throat-clearing.
Understanding that dry mouth may be a situation we are neither aware of nor have control over, throat-clearing is one we can definitely be more mindful of. Once or twice, usually the audience is often forgiving enough. We do have a little bit of control. Covering the mic or turning your head away from the mic helps A LOT. I loved in this post by friend and fellow speaker Mark Dalrymple, his mention of keeping a bag of throat lozenges handy, just in case. A great many tips in there!
I know. As if we weren't already self-conscious enough, now we have to worry about making weird sounds in the microphone, from conditions we may or may not have control over. This tip is an odd one and may seem petty, but for the sake of audiences everywhere (and how they receive you) it's something many speakers *could* be more mindful of.