Not sure about the water source, but we've got tea, coffee and aiva fruits for a reasonable price.

A good water source is down the road.

Description from OpenStreetMap: Known to overprice his services, so negotiate before ordering!

I've read a lot of mentions about Yusuf's cafe while preparing for the Lycian way.

Helpful information from https://www.facebook.com/groups/152628881520503/posts/8715260255257280/:
Between Göynük and Geyikbayırı, the only option to get food on the trail is at Yusuf's cafe in Elmayanı, as the shop in Hısarçandır has closed. Be careful with Yusuf, and agree on a price with him before ordering. There are reports he will try to rip you off when you don't. He's an elderly man trying to make a living in a remote village, and doesn't seem to have gotten rich from his practices though. We bought a loaf of bread from him for 30TL, but he also tried to charge 30 TL for filling a bottle of water from his tap.

This man sales tea and water at big price