The plunger positive displacement pump was first introduced to the wastewater treatment industry by the Ralph B. Carter Company in the early 1930's. From that time till now, the plunger pump has been a mainstay of wastewater treatment plant design. The reason for this longevity has been the success of this pump design handling both the difficult to pump sludge streams within the treatment process and the ease of maintenance. Although no piece of equipment can function without service or signficantally beyond design parameters, the Carter plunger pump's simple and basically rugged design will, in most cases, forgive poor maintenance and periodic excess pressure and load conditions without failure. The dividend of proper maintenance and application has been extremely long service life, in some cases, as much as forty-five years of continuous operation.