I would not give charcoal. Next time you fill their water, fill with warm water, not cold water, and if they look like they're gonna guzzle a bunch, let them drink a little, remove it, wait 15 minutes, return the water, let them drink a little more, remove water, and repeat this until they are not guzzling.If it happens again how should I get the charcoal in? It doesn't go in a tube and they won't eat when they're like that.