Increasing human population combined with increased economic growth and the concomitant consequences of increased urbanisation and associated environmental burdens coupled with climate change and water scarcity result in very serious challenges to global water security.Governments need to consider all solutions that can help achieve sustainable access to required quantities of acceptable quality water for human and ecosystem needs.Alternative technologies and approaches to water resource protection can play a significant role in protecting against water-borne pollution.The use of biological treatment systems such as constructed or engineered wetlands is an example of an alternative approach for secondary wastewater treatment.Constructed wetlands make use of the natural biogeochemical cycles of plants and bacteria, and filtering effects of soil media for the transformation, and mineralization of organic matter in wastewater.Treatment wetlands and engineered or augmented wetland systems have been shown to perform very well in temperate to cold temperate regions for polishing primary and secondary wastewater effluents.Performance results of treatment wetlands operating in cold conditions in Canada are presented.With appropriate design and proper operation and maintenance, wetland systems can effectively remove a variety of contaminants.Minimum sizes and residency times for water must be observed or other options such as added aeration or pump dosing must be considered if increased or accelerated treatment is required.Constructed wetlands as a passive, low-capital cost, low-operational cost technology are examined with recommendations for application in China.