The suitability of using treated wastewater for mixing concrete was experimentally evaluated. Concrete cube specimens were cast using tap water TW), preliminary treated wastewater PTWW), secondary treated wastewater STWW), and tertiary treated wastewater TTWW) obtained from the local Reqqa wastewater treatment plant.

The type of water used for mixing did not affect concrete slump and density. However, setting times were found to increase with deteriorating water quality. PTWW and STWW were found to have the most effect on retarding setting time. Concrete made with PTWW and STWW showed lower strengths ie, slower strength development) for ages up to 1 yr. At early concrete ages of 3 and 7 days, the strength of concrete made with TTWW was higher than that of concrete made with TW. The possibility of steel corrosion increased with the use of STWW and PTWW, especially when a thinner cover to the reinforcing steel was used. In summary, tertiary treated wastewater, of the type produced from wastewater treatment plants in Kuwait, is found to be suitable for mixing concrete with no adverse effects.