German to English Art/Literary General / Conversation / Greetings / Letters Austrian fairy tales

I'm working on a collection of Austrian fairy tales and have gathered a lot of phrases that I take to be out-dated idioms. I was wondering if anyone could confirm my interpretations and/or help with suitable translations.

This is also from "Der junge Graf, der in die Unterwelt kam".

"Da kamen sie an eine wunderbare klare Waldquelle, und den Grafensohn erfaflte ein heftiges Verlangen, von dem Wasser zu trinken. Die beiden Diener wollten ihm einen vollen Becher reichen, doch er sagte: "Ich stelle mich nur auf das **Brunnenbrett**, reitet ruhig weiter!""

The young count is not allowed to step on bare earth. I suppose this is some kind of board around the edge of the spring but don't know if there's a word for such a thing. Does anybody else know better? Thanks!