Background: Synthetic coagulants commonly used for water treatment are associated with undesirable properties, such as inefficacy and toxicity in addition to being expensive. Natural coagulants are considered safe and economical alternatives for developing countries where the plants are abundantly available.
Methods: The phytochemical composition and safety of water samples treated with Mangifera indica (M. indica) were evaluated in 13 groups of albino rats (N=36) for four weeks and compared with water samples treated with alum and calcium hypochlorite, using biochemical and hematological parameters. 
Results:  Mangifera indica bark contained alkaloids, flavonoids, saponins, phenols, tannins, terpenes, steroids and cardiac glycoside. Both the raw water samples (rivers, ponds & streams) and treated waters (alum, calcium hypochlorite and plant material) did not caused any significant (p>0.05) changes to the activities or levels of transaminases (AST and ALT), alkaline phosphatase, total serum proteins, urea, creatinine, sodium, potassium, platelet and mean corpuscular hemoglobin concentration compared with those in normal control rats. Water samples treated with M. indica caused significant increases (p<0.05) in packed cell volume, hemoglobin, and red blood cells of the animals while the untreated water samples significantly increased the white blood cell. However, alum treated water significantly increased (p<0.05) the concentrations of serum urea, sodium and potassium while calcium hypochlorite treated water significantly (p<0.05) increased the creatinine and potassium concentrations.
Conclusion: The use of M. indica bark in water purification confers hematopoietic properties to the water and reduces adverse effects on the biochemical parameters, thus could be considered as an effective and safe agent for water purification.