Availability of fresh water is decreasing in the present world because of extensive human activities in the nature. The alternative solution to meet the scarcity of abundance of fresh water is treatment of wastewater using a sustainable, ecofriendly and economic technology like phytoremediation in constructed wetlands. Currently, a comparative study between the efficiency of a sub-surface constructed wetland using Canna indica and Phragmites australis is discussed. Two cells of dimensions 3mx1.25mx1m each were constructed to treat domestic wastewater from Sri Lakshmi Aditya Boys Hostel mess, Surampalem with a total capacity of 3750 lit per day, to release 1000 lit of treated water daily. A two-stage sedimentation process, followed by pumping the effluent to a collection tank, from which a flow of 567.2 lit/hour is maintained to the constructed wetland daily. This water is retained in the wetland beds for a period of 6 to 7 days, then the treated water is collected in an underground sump. Plants in the surrounding area of the wetland are watered with the treated water using drips during dry seasons and left to ground water recharge during wet season. The working efficiency of the wetland is assessed by fort night cumulative physio-chemical monitoring of Water Quality Index (WQI) of the treated water periodically for a duration of 2 and 1/2 months. In the treatment of waste water with WQI of 505.98, Canna indica has comparatively shown improvement in treatment with WQI of treated water as 80.74 against 114.31 for Phragmites australis.