The official reports states: "drowning and effects of atherosclerotic heart disease and cocaine use."
The coroner also explains that cocaine and metabolites were found in her system, reports USA Today.
"Cocaine and metabolites were identified and were contributory to the death. Marijuana, Alprazolam (Xanax), Cyclobenzaprine (Flexeril) and Diphenhydramine (Benadryl) were identified but did not contribute to the death," states the report.
Houston was found unresponsive in her Beverly Hilton hotel room on February 11, 2012.
A private, invation-only funeral took place the following week in Newark, N.J., in the church where she first started singing as a young girl.
Houston is survived by her mother, brother and sister-in-law, cousins, including singer Dionne Warwick, and her only child and heir to her estate, Bobbi Kristina Brown.