Treasury Capacity
If your Treasury is full and you are rewarded with more resources, the overflow resources will be lost. To use the resources you must “collect” them. This will send the resources directly to your regular storages.
How much loot do you lose when raided?
“The percentage of Gold and Elixir that can be stolen from mines and collectors is 50% and is capped only by the storage capacity of the resource collector.” “The percentage of Dark Elixir that can be stolen from drills is 75% and is capped only by the storage capacity of the drill.”
How do you get dark elixir in your treasury?
Use your treasury to store extra dark elixir.
You can gain loot in your treasury from clan wars, clan games, and star bonuses.