Steam assisted gravity drainage (SAGD) heavy oil recovery facilities have traditionally used a combination of arm or hot lime softening, filtration, and weak acid cation (WAC) ion exchange to pretreat de-oiled produced water. The pretreated water is directed to "once-through" steam generators (OTSG) to produce 75-80% quality steam. The steam-water mixture goes through a series of vapour-liquid separators to produce the 100% quality steam required for injection into the oil well. The steam fluidizes the heavy oil and allows the oil/water mixture to be brought to the surface. The oil is recovered as product and the produced water is de-oiled an treated for reuse in the OTSG. An alternative method of produced water treatment and steam production, which has recently been implemented in Alberta by Deer Creek Energy, is mechanical vapour recompression evaporation followed by standard drum boilers. This method of SAGD steam production is much simpler to operate, is more cost effective, and results in significant increases is equipment reliability, on-stream availability, and ultimately in increased oil production. In conjunction with this process, Deer Creek Energy has taken the additional step of recovering all liquid waste streams for reuse in the plant, resulting in zero liquid discharge (ZLD). Designing the facility for ZLD eliminates the need for deep well injection, minimizes make-up water requirements, and simplifies the permitting process.