The method of using geothermal energy that involves moving water between about 10 and 20 feet deep in the earth to cool or heat water is known as a shallow geothermal system , specifically using closed-loop geothermal heat pump systems with horizontal or shallow vertical pipes. In these systems, pipes circulate a fluid (water mixed with antifreeze) through the ground at shallow depths-often between 1 and 20 feet (or slightly deeper)-where the temperature remains relatively constant year-round (around 10°C or 50°F). This fluid absorbs heat from the ground in winter to warm buildings and transfers heat back into the ground in summer to cool buildings. The heat exchange occurs via a heat pump that raises or lowers the temperature as needed for heating or cooling

. More details:

• Closed-loop systems use polyethylene pipes buried horizontally at shallow depths (typically 1 to 1.5 meters, about 3 to 5 feet) or vertically down to several hundred meters, but the shallow horizontal systems are commonly around 10 to 20 feet deep. The fluid circulates continuously, exchanging heat with the ground

• The constant ground temperature at these depths allows efficient heat transfer for both heating and cooling purposes, making it a renewable and space-saving method

This method contrasts with open-loop systems, which pump groundwater directly from wells and reinject it after heat exchange, usually requiring deeper wells and suitable aquifers

. In summary: The method is called a shallow geothermal heat pump system using a closed-loop horizontal or shallow vertical ground loop that circulates water or a refrigerant fluid through pipes buried roughly 10 to 20 feet deep to provide heating and cooling