Geothermal Wells in Ohio

State Coordinating Committee on Ground Water

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Geothermal heating and cooling uses the relatively constant temperature of the earth to heat and cool homes and businesses with 40 percent to 70 percent less energy than conventional systems. In winter, the relative warmth from the ground or ground water is transferred to the building, and in summer the process is reversed and the heat of the building is transferred to the earth or ground water.

Geothermal heating and cooling systems can be divided into two broad classes: open-loop systems and closed-loop systems. An open-loop system withdraws ground water from a well, passes it through a heat exchange system and discharges the temperature-altered water either back to the ground via a return well or to surface water. A closed-loop system circulates a heat transfer fluid (usually water with an antifreeze additive) through a loop or multiple loops of piping installed below ground or within a surface water body. A closed-loop system does not involve the withdrawal of ground water.

Open Loop Geothermal System
Closed Loop Geothermal System

For more information on the installation, operation and decommission of geothermal heating and cooling systems in Ohio:

For additional information, contact the Ohio EPA, Division of Drinking and Ground Waters by email at or phone at (614) 644-2752.

Laws, Rules and Referenced Standards for Geothermal Heating and Cooling Systems in Ohio

  • OAC 3745-9 Well Standards (Ohio EPA)
  • OAC 3701-28 Well Standards (Ohio Department of Health)
  • ORC 1521.05 Well Construction Logs and Well Sealing Reports
  • OAC 3745-33 and OAC 3745-38 National Pollutant Discharge Elimination System (NPDES) Permit 
  • OAC 3745-34 Underground Injection Control 
  • ORC 1521.16 Registering Facilities Capable of Withdrawing More Than 100,000 gallons a Day 
  • ORC 1522 Great Lakes St. Lawrence River Basin Water Resources Compact 
  • ORC 1521.17 Determination of Reasonableness of Use of Water

Referenced Standards


I'm considering having a geothermal heating and cooling system installed at my home or business. Whom should I contact first for more information?

Property, home and business owners considering installing a geothermal heating and cooling system should contact a heating and cooling system professional or architect for information on system design and applicability.

Are there any state laws or regulations restricting the installation of geothermal heating and cooling systems?

Yes. Closed-loop geothermal heating and cooling systems may not be installed within the sanitary isolation radius of a public water supply well. There are no other restrictions in state law on siting geothermal heating and cooling systems. However, local siting restrictions may apply. Please contact the local health district, zoning board or commission and/or building department for additional information.

Do well records need to be filed for geothermal systems?

Yes. For open-loop systems, a well record needs to be filed for each well (both extraction and return wells). For closed-loop systems with less than 20 borings, a minimum of one well record is required. On the record, state the number of borings that were installed along with the coordinates for each boring. For systems that have greater than 20 borings, five well records should be submitted; one each at the four corners of the grid and one record for the boring closest to the center of the grid. All well records should be submitted to the

ODNR Division of Soil and Water Resources and other agencies depending on the type of use (e.g. the local health district if the well is also used for domestic purposes, or the Ohio EPA UIC Program if the well is a return well).

Does the fluid inside a closed-loop geothermal heating and cooling system pose a threat to ground water if it leaks?

Yes, but it may be minimal, depending on the antifreeze used and the volume of fluid involved. Most closed-loop systems circulate a water-antifreeze mixture. The antifreeze constitutes 10-20 percent of the volume. Many closed-loop geothermal heating and cooling systems use methanol or ethanol as antifreeze. Both of these break down rapidly in the subsurface. Propylene glycol, a food-grade antifreeze, is also used. Some antifreezes are toxic and should not be used where the ground water is being used for drinking water. Closed-loop systems are also equipped with sensors that automatically shut-off the system if the pressure drops, minimizing the amount of fluid released from the system in the event of a leak.

Should geothermal heating/cooling systems be permitted within a source water protection area?

In Ohio, state law does not restrict the siting, installation or operation of a geothermal heating/cooling system within a source water protection area. However, the guidance presented here recommends that if a closed-loop system is proposed within the inner management zone of a source water protection area, the antifreeze used should be food-grade (for example, propylene glycol). Ohio EPA encourages concerned community leaders to work with their local planning offices to provide a mechanism to ensure that installation and operation of such systems is protective of ground water quality.

How do I determine if a property is in a source water protection area?

To determine if a proposed closed-loop system is located within a source water protection area, contact Ohio EPA's SWAP program at:
Ohio EPA, Division of Drinking and Ground Waters
Source Water Assessment and Protection Program

50 W. Town St., Suite 700

Columbus, OH 43215
Phone: (614) 644-2752
Fax: (614) 644-2909

Please include the following information in your request:
  • The location of the existing or proposed facility (a map showing the proposed system location is preferred)
  • The reason for your request
  • Your contact information, including your email address


Information Officer

Craig Smith
Ohio EPA, Division of Drinking and Ground Waters
P.O. Box 1049
Columbus, OH 43216-1049
Email Craig
(614) 644-2752 Phone
(614) 644-2909 Fax


Jim Raab
Ohio Department of Natural Resources
Division of Geological Survey
2045 Morse Road, Bldg. C-2
Columbus, OH 43229
Email Jim
(614) 265-6747 Phone


Craig Nelson
Ohio Department of Natural Resources
Division of Geological Survey
2045 Morse Road, Bldg. C-2
Columbus, OH 43229
Email Craig
(614) 265-6603 Phone