A ketracel-white facility was a location where the Dominion stored and distributed its ketracel-white supply. Jem'Hadar ships approached these facilities and requested to be resupplied with canisters of white. The ship then beamed down a number of canisters from its cargo hold and was given the same number by the facility. Some facilities were equipped with security nets.
Three months into the Dominion War, Starfleet Intelligence discovered the location of a facility in Cardassian space near a dark-matter nebula. Admiral William Ross gave Captain Benjamin Sisko and his crew the mission to destroy it.
Using a Jem'Hadar ship they had captured a year earlier, the former crew of Deep Space 9 equipped one canister with ninety isotons of enriched ultritium which would be detonated with a timer attached to it. The canisters were beamed down and the facility transported full canisters to the ship. However, the security net was raised and the facility told them to stand by. The timer detonated the ultritium soon after, earlier than set, triggering a large explosion. As the ship moved away, a larger explosion destroyed the rest of the facility and the asteroid it was built on. (DS9: "A Time to Stand")
The Federation heard rumors of the establishment of a new facility somewhere in Sector 507 in early 2375. Weyoun later confirmed the rumors were true, telling Odo it was in the Pelosa system. (DS9: "Treachery, Faith and the Great River")
The Son'a had a ketracel-white facility in an outpost on Devos II. The Federation became aware of its presence later in 2375, forcing Weyoun and Damar to divert warships from pursuit of the USS Defiant to the facility to protect it. (DS9: "Penumbra")