Processes and systems suitable for purifying or otherwise treating liquids to remove contaminants therein, including but not limited to contaminated water, to permit reclaiming, recycling, and reuse of the liquids. Such a process and system entails the use of a cascading distillation system that evaporates a liquid from the feedstock and then condenses and collects a more purified form of the liquid. The cascading distillation system can be operated to selectively process the feedstock through any of a series of vessels at which different amounts and/or contaminants may be removed from the feedstock.