Delhi Jal Board — Pending Dues from DDA

Address:

Rohini

I bought the flat in DDA Flat in Rohini Sec-23, earlier water supply and billing was taken care by DDA only, in 2019 DDA has hand over the water & sewer to Delhi Jal board, now recently DJB has started generating bills and showing dues from DDA pf Rs 41000/-, I have NOC form DDA as well till 2019 there was no dues, kindly suggest how can i proceed further to nullify the overdues.