While submersible pumps are more efficient than jet pumps in delivering more water for the same size motor, pump or motor problems will necessitate pulling the unit from the well casing-a job that's best left to a pro. However, submersibles are known for their reliability and often perform their role 20 to 25 years without servicing. Submersible pumps may also be used in shallow wells. However, silt, sand, algae and other contaminants can shorten the pump's life.