The present invention consists of a method of pre-treatment of adulterated water for distillation, including adulterated water produced during hydraulic fracturing ("fracking") of shale rock during natural gas drilling. In particular, the invention is directed to a method of treating adulterated water, said adulterated water having an initial level of bicarbonate ion in a range of about 250 ppm to about 5000 ppm and an initial level of calcium ion in a range of about 500 ppm to about 50,000 ppm, said method comprising contacting the adulterated water with a non-thermal arc discharge plasma to produce plasma treated water having a level of bicarbonate ion of less than about 100 ppm. Optionally, the plasma treated water may be further distilled.
 The subject matter disclosed herein was made with government support under RPSEA's Prime Contract DE-AC26-07NT42677, awarded by the Department of Energy through the "Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources" program authorized by the U.S. Energy Policy Act of 2005. The Government has certain rights in the herein disclosed subject matter.