For maintenance of drinking sources and biodiversity actions on additional purification of urban rainfall runoff are required. Application of water hyacinth (Eichhornia crassipes) from the family of pontederia (Pontederiaceae) with increased level of metallothioneins is necessary as efficiency of wastewater phytoremediation increases. It has been shown, that the efficiency of extracting heavy metals from wastewater can be increased due to ionic preinduction of metallothioneins by means of ions Cd within the root system of plants (Eichhornia). The efficiency of this technique has been estimated in terms of the risk these heavy metals may present to the health of Moscow inhabitants. © Springer Science+Business Media B.V. 2011.