Shortage of water throughout the world dictates utilization of marginal water for irrigation. Treated urban wastewater is a common alternative water source for irrigation in arid and semiarid regions. In this study we aimed to evaluate the eff ect of irrigation with secondary-treated effl uent on plant development, essential oil yield, antioxidant activity and selected antioxidant phenolic compounds in two commercial cultivars of the aromatic species, oregano (Origanum vulgare L.) and rosemary (Rosmarinus offi cinalis L.). Th e applied treated effl uent contained higher levels of Na, Cl, HCO 3 -1 , P, K, NH 4 +1 , NO 3 -1 , Ca+Mg, B, Mn, and Fe than the local potable water used as control, and were characterized by higher values of electrical conductivity (EC), pH, and sodium absorption ratio (SAR). Since effl uent eff ects on plants can become apparent only following several years of exposure, the plants were exposed to the water treatments for 3 yr. Despite the diff erences in water quality, the effl uent did not aff ect yield quantity and quality in either crop. Plant morphological development, biomass production, percent dry leaves of the total biomass, quantity and composition of the essential oil produced, antioxidant activity, and contents of selected antioxidant-phenolic compounds were not aff ected by irrigation with treated effl uent compared with potable water. Our results demonstrate that both oregano and rosemary are suitable as industrial crops for essential oil and antioxidant production under irrigation with secondary-treated municipal effl uent because their yield quantity and quality were not aff ected.

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