Hi, is there a chance that you have photo of this or maybe could provide more details. Because there is already tagged similar amenity near this note. 

You can see it here: https://www.openstreetmap.org/node/5032715762

In past it used to be tagged as drinking water, but then some user changed it to amenity=watering_place. Difference is that drinking_water is place where humans can drink, while watering place is spot where animals drink water. Just want to be sure before making any change.