Abstract According to water crisis at most of the countries of world, population growth and industrialization of life, there is urgent need to use from water resources at different societies. Under such conditions that we are facing with limitation of water resources inevitably we have to use from uncommon waters including wastewater in agriculture. Before using irrigation with wastewater in agriculture, we shall conduct vast studies about effects of wastewater on agricultural soils and even different agricultural plants. In this relation we have studied the effect of irrigation with domestic wastewater and first and second drainage water by method of lysimeter on changes of field capacity. Therefore we had used from comparison of averages with presence of witness. 15 lysimeters were installed in farm. In the first 5 lysimeters Brassica napus l which is an industrial plant was cultivated. On the floor of exit lysimeters drainage water was installed for discharging water. In the lysimeters No.5 to 9 alfalfa was cultivated which can be used by farm animals. In third 5 lysimeters basil that is both edible and pharmaceutical plant was cultivated. At the end of pilot 3 lysimeters containing aforesaid plants was installed and irrigated with well water. Before conducting experiment the field capacity inside of lysimeters was measured. Then irrigation with domestic wastewater and first and second drainage water was started and process of cultivation, storage and harvest of aforesaid plants was terminated. The field capacity of Brassica napus l lysimeters that were irrigated with domestic waste water was compared with of 4 alfalfa lysimeters and 3 basil lysimeters and finally their average was compared with field capacity of 5 lysimeters that were irrigated with well water. From this comparison we concluded that the field capacity while being irrigated with domestic wastewater was increased 8.5% in comparison to witness and field capacity while being with first drainage water was increased 7.5% in comparison to well water and field capacity while being irrigated with second drainage water was increased 1% in comparison to well water. تفاصيل المقالة