How is mAyy pronounced? What sound does your capital A represent?It's feminine in all Levantine dialects (mayy or mAyy etc). I think, based on the ending, that it's also feminine in Egyptian (mayya).
Same for the Maghreb. ماء (maa or méé according to the area) is the only term I've ever heard. As Djara said, if ماية is used, it's only as a diminutive personally, and I've never heard it in Morocco.The traditional Najdi/bedouin word is ما maa, which is masculine