The Elixir Collector collects Elixir from an unlimited underground reserve and stores it until collected by the player and placed into an Elixir Storage. When the collector is full, production will be stopped until it is collected (or raided by an enemy player).
The production rate and capacity depends on the level of the Elixir Collector. Players can get an idea of how much Elixir the collector is storing by how full the tank appears.
The Elixir Collector takes up a 3x3 space.
When you choose to upgrade an Elixir Collector, it will automatically collect any uncollected Elixir. Note that if your Elixir Storages are full at that time, the uncollected Elixir will be lost! During the upgrade the collector stops producing Elixir.
Once the Elixir Collector is level 5, you can temporarily boost its production with Gems. Spending Gems will double the Collector's production for 1 day.
It is a good idea to put your Elixir Collectors outside of your Walls, so they can act as a distraction to units such as Barbarians and Archers.
Attackers can steal up to 50% of the uncollected Elixir in the collectors. Having too many uncollected resources will make you a more attractive target.
If an Elixir Collector is destroyed in an attack while it is being upgraded, no Elixir will be lost as the collector is empty during this time.
Pay careful attention to the location of Elixir Collectors when planning your attack, as Elixir Collectors are usually only marginally protected and can be quite lucrative, especially at high levels. Many times a single Archer can be placed in such a way that it can destroy an Elixir Collector while standing clear of any defenses.
If you see a round number of Elixir in a raid, it is most likely going to be in the Elixir Collectors rather than in the Elixir Storages (example 90,000). Although round numbers can occur in Elixir Storages, they happen much more often when Elixir Storages have been emptied by a previous raid and the resultant shield has allowed the Elixir Collectors to completely fill up.
Elixir Collectors undergo significant visual changes at levels 5, 8 and 10.
When initially constructed, the Elixir Collector consists of a large, transparent cylindrical vat standing vertically on a wooden base. A long, narrow metal tube extends from the top of the vat and bends down to a small brass pump with shutoff valve embedded in the ground. Elixir periodically bubbles out of the air vent on the top of the vat.
At level 2, a second narrow metal tube appears, and the brass pump grows larger. Additional tubes are added at levels 3 and 4, with the pump also increasing in size.
At level 5, the four narrow metal tubes are replaced with one much larger diameter tube, and the brass pump and shutoff valve moves to the opposite side of the collector. A flat metal skirt appears around the base of the collector as well.
At level 6, a second, smaller metal tube appears, connecting to a smaller (valveless) pump on the opposite side of the collector. The level 7 Elixir Collector adds another smaller tube.
At level 8, the two smaller tubes on the left side of the collector are replaced with a single large-diameter tube, which joins the original tube at the top of the collector. The second pump on the left side of the collector receives a small shutoff valve wheel as well.
At level 9, the wooden cap on the cylindrical vat is replaced with brass. The collector gets a third large tube coming from the back and a brass reinforcing bar appears on the front of the vat.
At level 10, the top of the collector receives a large brass junction where all the tubing enters. Two additional large-diameter tubes are added as well, for a total of five. Shutoff valves are visible on three of the tubes as well as on the top of the junction. Additional reinforcing bars appear on the front of the vat.
At level 11, the shutoff valve on the top of the vat disappears, replaced by still more tubing. The reinforcing bars are replaced with wide brass reinforcing plates that nearly cover the entire vat.
It takes 10 days, 21 hours and 21 minutes to fully upgrade the Elixir Collector.
A downside with Elixir Collectors is that even though the cost to upgrade them is low, the time it takes to complete them is relatively long.
Although every other number matches between the Gold Mine and Elixir Collector, the level 5 upgrade prices are different (3,000 Elixir for the Gold Mine, 3,500 Gold for the Elixir Collector).
The "Catch Up Point" is the time at which the newly upgraded collector has equaled the total production of the collector had it not been upgraded - this does not consider recovering the cost of the other resource required to perform the upgrade.