In this study an attempt has been made to estimate the vitality of the common reed (Phragmites australis) grown in the constructed wetland. The efficiency of solar radiation uptake of leaves was measured and terminal electron transport system (ETS) activity of roots was determined in specimens from different locations on the reed bed. The results showed that photochemical efficiency of PS II, expressed as FvFm ratio, was higher in plants growing in the middle of the well established stand, but it was lower in plants growing in the area permanently flooded with leachate, where plants were significantly lower. Potential respiration of roots on the vertical rhizome decreases with depth, while it showed slight variations when determined at the same depth, but in plants from different locations within three beds of RBTS.