Muya seems to be a mountain in Sudan. (Alternate) Arabic names are Dschabal Mūya, Jabal Mayyah, Jebel
Moya, Gebel Moya or Dschebel Moya.
source:
http://de.wikipedia.org/wiki/Muya (Sorry, it's all German but I didn't find anything on English wikipedia at first)
I only found some articles on English wikipedia containing 'Jebel Moya' because the German article said this was the name used in specialist literature:
http://en.wikipedia.org/w/index.php?title=Special%3ASearch&search=Jebel+Moya
There is no mentioning of its usage as a first name or meaning 'water' but the article says it's located between Blue Nile and White Nile which would explain an association with water by your neighbour.
A google search of 'Jebel Moya' only brought up geographical and archaeological references, nothing on a first name use. Sorry.
This message was edited 8/30/2011, 10:10 AM