The aim of this study was to obtain a natural coagulant from moringa seed powder and use it to treat water from rural cisterns. The moringa seeds used in the work were purchased in the municipality of Cajazeiras-PB. For the chemical composition of the seeds, proteins, lipids, ash and moisture were assessed at the Physical-Chemical Analyses Laboratory of the IFPB Sousa Campus. The moringa coagulant was obtained in an aqueous medium. The water used in the work came from cisterns built in the Santo Antonio settlement, in the municipality of Cajazeiras - PB. The water used was analysed before and after treatment. The following parameters were analysed: pH, electrical conductivity, probable residue, CaCO3, NaCl and total alkalinity, faecal coliforms and Escherichia coli. The seeds showed a high percentage of protein (34.22 per cent). The protein in moringa seeds is the most important compound in the water clarification process. All the chemical parameter analyses showed significant differences before and after treatment.