The Splash Water Bottle can not put the Campfire out. This should be considered a bug due to every other fire effect (leaves on fire or fire created by the flint and steel or fire charge) can be put out by a toss of the Splash Water Bottle. The only way, currently, to put out the campfire is by flooding it with a bucket of water but in an environment where free flowing water can destroy important blocks or connections, this would save possible hours of repair work.