As a bonus, you can make it super concentrated. I boil several huge batches in a row, in the same water. Let it cool and pour it into bottles. Just a few splashes will color up a couple quarts of water nicely.
I was boiling some live oak leaves last evening and looked at how dark the water was becoming. From now on I will save it for tads. Don't have any yet, but hopefully soon. This area is a forest of live oak, and the dry leaves are small and plentiful.