The consumption of hot water represents a significant portion of national energy consumption and contributes to concerns associated with global climate change. Utilizing heat recovered from the sewer or stored in the ground via a borehole geothermal energy storage system are simple and effective ways of heating water for domestic purposes. Reclaiming heat from the waste warm water that is discharged to the sewer or stored heat in a borehole geothermal energy storage system can help reduce natural gas energy consumption as well as the associated energy costs and greenhouse gas emissions. In this paper, sewer waste heat recovery is compared with geothermal heat pump systems for a small community shared water heating system. It is found that the heat recovery from the sewer heat exchanger method demonstrates the lowest rate of return on investment for the selected community size. The findings also demonstrate a significant reduction in natural gas consumption and CO 2 gas emissions. The results are intended to allow energy technology suppliers to work with communities while accounting appropriately for economic issues and CO 2 emissions associated with these energy technologies.