The population of Blaenllechau is less than 1000. The village is defined by the river border, flowing between Blaenllechau and neighbouring Ferndale, of which the well-known Blaenllechau waterfall is a tributary.
The population of Blaenllechau does not exceed 1000. The village is bounded by the river that divides it from Ferndale, a nearby area, and this river includes the famous Blaenllechau waterfall as part of its course.