Reuse of Treated Water from Domestic Use

A residential community of 200 families, has the water consumption of around 80,000 litres per day, which is treated and pumped into a stream, which is still of waste. I would like to understand, if such water can be reused, both with and without much processing? If so, I would like the experts to clarify in detail how and how the water can be reused? Thanks Murthi