A probabilistic prediction of the bacterial number in the waste stabilization pond has been considered. A divergence from the existing deterministic models for the bacterial number estimation, this method considers the waste stabilization pond as stochastic process. Under the assumption of a truncated normally distributed bacteria die-off rate, the distribution of the bacteria number at any distance from the influent point is obtained. Unlike the deterministic models, this probabilistic approach gave the quantitative chance variations in the bacteria number after a stipulated distance interval.