The coroner looking into the death of toddler Aisling Symes has asked that Waitakere City Council provide him with its report into the incident.
The two-year-old's body was discovered last month in a stormwater drain after a week-long search.
Residents say they had made numerous complaints about flooding that would sometimes cause the drain's 20kg manhole cover to come off.
It had been found ajar on the day the toddler went missing.
The council says its report is being prepared with independent input and the coroner has asked for it by 16 November.
Acting Chief Coroner Garry Evans announced on 14 October that he would hold an inquest into the child's death.