On the map the blue dot, the source, is not on the right place. The source between Prodromou and Lavra near the house of Ag. Triada is located on the side path. See the red arrow which I added.

Coming from Lavra , walking to Kavsokalivia this sign brings you on the side path and after 50 meters to the source.

Once we came from Prodromou, walking the road and could not find the path. I knocked on the door of Agia Triada to ask for directions. An annoyed monk opened the door, I started in English but he interrupted me, shouting: ” SPEAK GREEK”, and slammed the door.
The words ” speak Greek” became the running gag during our stay in Greece.

Especially if you come all the way from Kavsokalivia or Anna it is really a pleasure to drink the cold pure water and fill your water bottle.

The source is erected in 1889. Vasilis translated the text (many thanks!):

With the help and at the expense of
the most Holy among the monks
Alypios from Lavra 1889
August 10
(no verb)
ΔΙΑ ΣΥΝΔΡΟΜΗΣ ΚΑΙ ΕΞΟΔΩΝ
ΤΟΥ ΟΣΙΩΤΑΤΟΥ ΕΝ ΜΟΝΑΧΟΙΣ ΑΛ
ΥΠΗΟΥ ΛΑΥΡΙΩΤΟΥ 1889
+ ΑΥΓΟΥΣΤΟΥ 10 +

Herman Voogd