Graphical abstract Percentage turbidity reduction of the samples Abstract This research was carried out to evaluate the effectiveness Calotropis procera leaves as an alternative to the use of chemicals as coagulants in water treatment. Calotropis procera leaves were plugged, washed with distilled water, cut into small pieces and then dried in an oven to a constant weight. After which the leaves were grinded into various particle sizes of 1 mm, 2 mm and 0.71 mm. Raw water from River Kaduna at

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... ala and Kakuri areas within Kaduna metropolis were treated with different samples classified based on the dried Calotropis procera leaves particle size and weight, sampling location and the treatment time. The physico-chemical characteristics of the treated samples were all within the allowable standard by World Health Organization (WHO). The results show that the treated water sample D with 0.71 mm particle size and 40 g weight of the dried Calotropis procera leaves gave the highest percentage reduction in turbidity. Treatment of the samples with Calotropis procera leaves gave a significant reduction in coliform count from 21 per 100 ml to 1 per 100 ml in treated water samples E and F. This study shows that Calotropis procera can be used as a low-cost, environmentally friendly substitute coagulant for water and wastewater treatment.