More than 13,100 gallons of home heating oil are spilled every year in Connecticut, according to a new report by the state’s official environmental watchdog, costing state taxpayers nearly $7 million annually.

The Council on Environmental Quality is warning that such spills can endanger this state’s drinking water supplies and is urging reforms to help curb the problems.

Sixty-five percent of home heating oil spills in Connecticut occurred at private, non-commercial properties and were primarily caused by corroded above ground and underground storage tanks.

Those proposed reforms include tighter state regulations to require fuel oil safety features that are already mandated in states like Vermont and Massachusetts. The agency is also recommending state action to require periodic inspection of home heating oil tanks and more funding to help people replace outdated and inefficient oil heating systems.

According to the new report, home heating oil spills that were reported to the state between 2010 and 2018 numbered about 7,520 and accounted for approximately 104,800 gallons of spilled fuel. Each spill incident cost the state an average of $7,400.

But the watchdog agency’s report warns that not all heating oil spills are properly reported to the state.

State records indicate that 65 percent of those heating fuel spills occurred at private, non-commercial properties and were primarily caused by corroded above ground and underground storage tanks.

State officials routinely seek to recover the costs of those incidents from homeowners or heating oil suppliers. The council’s executive director, Peter Hearn, warned that not all home insurance policies cover such costs.

“While any release of heating oil to the environment is bad, its impact on a drinking water supply is a grave concern to the affected residents and public health agencies,” council officials said in a statement about the report. “Groundwater contamination may present a health risk to some of the roughly one million [Connecticut] residents who use groundwater as a source for drinking, bathing or cooking.”

“Given the fact that almost a third of the state’s residents rely on groundwater for their potable water, it’s critical that we find practical solutions to minimize the number of heating oil releases from locations in the state that use oil for heating,” said Susan Merrow, chair of the Council on Environmental Quality.

The council’s recommendations for reducing the number of heating fuel spills include requiring safety features such as sleeved supply lines, vent alarms to prevent overflows when home tanks are being filled, and safety valves.

Another recommendation is for the state to require periodic inspections of heating oil tanks and supply lines by qualified technicians.

The report also urges additional funding be provided through energy assistance programs to help homeowners and landlords upgrade or replace old fuel oil heating systems.

Another proposal by the council is for the state to improve its webpage on home heating oil to provide people with more information about spill insurance coverage and potential sources of financial help for improving heating systems.