This paper explains the behaviour of E.coli on decay phase condition in Abua-Odua in Niger Delta of Rivers State; the model shows the variation of degradation of E.coli in shallow aquifer. Furthermore, it is confirmed that the decay phase condition of E.coli migration on stratum deposition in groundwater aquifers, does not completely free it from solute, due to other influences that may cause regeneration of the microbes, increasing the level of concentration and degrade the quality of ground water. The study also explains the rate of concentration with respect to distance and duration within hundred days and thirty metres respectively. Finally, the model and the experimental results compared fits to the condition of decay phase; this implies that the model developed will be a benchmark in solving groundwater pollution transport of E.coli in decay phase condition in the study location.