The six-year old girl named Pakeeza had gone missing from a wedding hall in Orangi Town on 25th January.
The girl was raped and killed before being dumped into the water tank, alleged the relatives.
The body was shifted to Abbasi Shaheed Hospital for post-mortem.
Heart wrenching scenes were witnessed when her body was brought to her house for the last rites. Large number of people were present during the funeral prayers.
Ten people, including the hall manager, have been arrested so far whereas the wedding lawn has also been sealed.