Where to discharge excess treated STP water ?

Hello Sir,

I live in a apartment in South Bangalore which houses 160 flats. We have STP installed in our apartment complex. Excess treated STP water is used currently for flushing and gardening. Additionally we can plan to use this water for washing basement area and car wash as well. But we will still end up having around 50000 Litres of treated STP water as excess per day. Kindly let us the know the legitimate way (UGD / Storm water drain/ or any other) to discharge this excess water.