The picture shows a few people line up for spring water called "Somei-no-mizu" ("mizu" means water). It is drinkable.
We can pour water into pet bottles brought from our home. Sign says the limit is 6 litters a day. There is a small box for us to put money. It doesn't say how much money we have to put in, but I always put a couple of dollars at a time for 1〜1.5 litters.
Somei-no-mizu is the only one we can still drink in Kyoto city.
There were three famous spring water for its great taste, but now 2 of them are run out.
One is inside a park around Imperial Palace and the other is now rebuilded at famous Japanese-style confection store at Rokujyo-dori in Kyoto city.
Nashinoki-jinja is very close to Imperial Palace, so I recommend you to visit Nashinoki-jinja and have some spring water to moisten your throat.