Your barrels should be fine to use as long as they are still moist inside.
A good way to check for this is by inspecting the bunghole. If the bunghole is not properly sealed with a rubber stopper, chances are that the barrel will be dried out.
If the barrel is dry, ensure that the metal hoops are properly connected and not loose - if they are not in their proper location, the barrel is not worth using as you won't be able to develop a liquid tight seal.
If your barrel is dry, you could attempt to salvage it by filling it 20% full with hot, chlorine-free (this is important - no chlorine) water. Put a bung in, shake it all around until water stops leaking from the seams of the barrel. Now, put the barrel right-side up and fill the outside of the head with hot water and let it sit for 20 minutes. Repeat for the other head (turn barrel upside down).
You can test the barrel by filling it all the way with water and watching for leaks. If it does leak, let the barrel sit full of water for 24 hours.
If it still leaks after this, your barrel is probably flawed.
Please keep in mind that the water you use will directly affect the flavor of your beer in the end. We recommend using a spring water bought from the grocery store - Deer Park has a nice neutral flavor in our opinion. Whatever you do, don't use tap water without a proper filter.
As for the beer, you might try something like Mikkeller's Black Hole (Tequila-barrel aged Imperial Stout). http://www.ratebeer.com/beer/mikkeller-black-hole-barrel-aged-edition-tequila/144100/
Anything with a high alcohol content will work well. You could experiment with a Saison even.
A tequila-aged barleywine sounds interesting to us!
Answered by: the Gastrograph Team