This problem was posted on stackoverflow 9(!) months ago http://stackoverflow.com/questions/38959321/firebase-databas... It has been updated recently: "After 9 months of back-and-forth emails (over 40 emails), Google has acknowledged that they have found some bugs that may be responsible for high bandwidth usage, but bandwidth usage is still too high. Resolving this issue does no appear to be a priority for Google/Firebase (it took them 1.5 months to respond to the last email)."