Wastewater recovered by in situ production of tar sand bitumen using steam drive or combustion processes must be treated prior to recycling in the process, reuse within the production facility, or discharge. Recent laboratory studies have shown biological treatment with activated sludge and reverse osmosis treatment to be potentially effective on combustion wastewater. The hot lime softening process has been used and strong acid ion exchange treatment has been proposed to treat wastewaters from commercial oil sand in situ steam drive facilities in Canada. The estimated costs associated with the construction and operation of wastewater treatment systems for projected 20,000 barrel-per-day in situ combustion and steam drive production facilities are presented. The treatment of the steam drive wastewater focuses on recycling the production wastewater to once-through steam generators. The treatment of the combustion wastewater focuses on discharging the effluent. The costs for wastewater treatment range from $0.249 to $2.765 (U.S.) per barrel of bitumen produced in mid-1984 dollars. The cost analysis methodology used may be applicable to other systems.