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Egyptian irrigation canals exposed to continual contamination due to the bad behaviors of some users. Such human activities reduce surface water quality and transfer the water into unsuitable source for irrigation, domestic or drinking. So, the decision makers adopted the solution of covering irrigation canals to protect the canals from such contaminations. The present paper evaluated the impact of covering irrigation canals on improving the quality of irrigation water. Three canals at Abu Kebier City, Sharkia Governorate, Egypt are selected. These canals pass through the residential area. Water samples are collected from the sites of covering at different locations. The laboratory analysis is conducted to obtain the values of water quality parameters. The impact of the covering at the location of the manholes inside the covering and downstream the covering is evaluated compared to the reference point which is located far away upstream of from the covered. A qualitative weighted impact scoring system is designed to evaluate the impact of the covering on two locations, at the manhole and just downstream of the covering for each measured water quality parameters. Although, covering the irrigation canal affects some of the surface water quality parameters positively, it generally has a negative impact on the water quality of irrigation canals because the net impact was negative at points of manholes and outlet. It is recommended to stop covering irrigation canals and seeking for another alternative which keeps the quality of water as it is without further contamination and use the water area as a source of refreshment for the residents.