Geothermal Heat Pump — Propylene Glycol Loop Fluid Leakage and Soil/Groundwater Impact (Antifreeze Loop, BOD Loading, Aquifer Contamination) — household safety profile
Low riskGround-source (geothermal) heat pump systems circulate a water-antifreeze solution — typically 20-30% propylene glycol — through hundreds of meters of buried polyethylene loop piping to exchange thermal energy with subsurface soil or groundwater.
What is this product?
Ground-source (geothermal) heat pump systems circulate a water-antifreeze solution — typically 20-30% propylene glycol — through hundreds of meters of buried polyethylene loop piping to exchange thermal energy with subsurface soil or groundwater. While propylene glycol is classified as GRAS (Generally Recognized As Safe) by the FDA for food use, its environmental behavior when released to soil and groundwater through loop system leaks, pipe failures, or improper decommissioning presents distinct concerns. Propylene glycol exerts significant biological oxygen demand (BOD) during aerobic biodegradation — 1 kilogram of propylene glycol consumes approximately 1.5 kg of dissolved oxygen, potentially creating localized anoxic zones in shallow groundwater that mobilize naturally occurring iron, manganese, and arsenic from aquifer sediments. A typical residential geothermal loop contains 200-400 liters of glycol solution; commercial systems may contain thousands of liters. Loop breaches from excavation damage, fitting failures, or corrosion release glycol directly into the subsurface at depths where natural attenuation is slow due to limited oxygen availability. Several US states now regulate geothermal loop fluids under groundwater protection statutes, with some jurisdictions requiring only water-based loops (no antifreeze) within wellhead protection areas. Decommissioning of abandoned geothermal loops requires proper flushing and fluid disposal — grouting of boreholes is mandated in most jurisdictions to prevent vertical aquifer cross-contamination.
What's in it
Click any compound name for its full safety profile, regulatory consensus, and exposure data.
Heat Transfer Fluid
Frequently asked questions
No FAQs generated.
Look up Geothermal Heat Pump — Propylene Glycol Loop Fluid Leakage and Soil/Groundwater Impact (Antifreeze Loop, BOD Loading, Aquifer Contamination) in the home app
Search by ingredient, browse by category, or compare to alternatives in the live app.
Open in home View raw API dataReference data, not professional advice. Aggregates publicly available regulatory and scientific information. Why we built ALETHEIA →