Hyderabad: A. Bushaiah, 25, and Pandu, 23, both labourers, died after drainage water accumulated in the newly laid pipeline for supplying Krishna water at Chilakalguda on Friday.They were checking valves of a sump in the pipeline at Mehmoodguda. "Water from a drainage line running parallel to this water pipeline accumulated in the sump. The resultant poisonous gases led to the death of workers," Inspector G. P. Vinod Kumar said.