Suspected Gas Leak in Your Home: What to Do and What to Never Do First
If you smell gas in your home, the only correct first action is to leave immediately without touching anything. Do not flip a light switch, do not unplug an appliance, do not open windows, and do not call anyone from inside the home. Once you are outside and away from the building, call 911. Then call the gas utility. Then call a licensed plumber for gas leak detection and repair. That sequence, leave first and call from outside, is the single most important guidance any homeowner can retain about gas leaks. Everything else in this guide covers why those actions matter, what causes gas leaks, how licensed technicians find and fix them, and the local factors in Noblesville and Hamilton County that make gas leak awareness especially relevant.
Thornton Plumbing HVAC and Electrical provides gas leak detection and repair throughout Noblesville, IN and the surrounding Hamilton County area. Licensed under Indiana Plumbing License PC11500008, fully bonded and insured, and BBB A+ rated since 2006, our licensed plumbers use combustible gas detection instruments to locate the source of a gas leak, complete the repair, and pressure test the line before service is restored. Gas line work for residential applications is covered under Indiana Plumbing License PC11500008, verifiable through the Indiana Professional Licensing Agency. Call 317-697-9265 at any time for gas-related emergencies.
What to Do if You Suspect a Gas Leak: The Correct Sequence
- Leave the home immediately. Do not pause to gather belongings.
- As you leave, do not flip any light switches, do not unplug any appliances, and do not use the thermostat or any electrical control.
- Leave doors open as you exit to allow some ventilation as you go, but do not stop to open windows.
- Move away from the building to a point where you are clear of any possible gas accumulation near windows or vents.
- Call 911 from your mobile phone or from a neighbor’s home.
- Call your gas utility. For most Noblesville addresses, this is the
- Call Thornton at 317-697-9265 for licensed gas leak detection and repair service once the utility has responded and addressed the immediate situation.
- Do not re-enter the home until the gas utility has confirmed it is safe to do so.
What NOT to Do When You Suspect a Gas Leak
The actions most likely to escalate a gas leak situation are ones that seem reasonable but create ignition risk.
- Do not flip any light switch. Light switches create a small electrical arc when operated.
- Do not unplug any appliance. Unplugging creates a spark at the outlet.
- Do not turn on a flashlight if it has a switch you need to flip. Use a phone screen instead.
- Do not call anyone from inside the home. Mobile phone radio transmission can create a small arc.
- Do not attempt to find the leak yourself by following the smell.
- Do not open the electrical panel. Any arc inside the panel is an ignition risk.
- Do not start a car in an attached garage. A car’s ignition system produces significant sparks.
What Causes Gas Leaks in Noblesville Homes
Aging and Corroded Gas Line Connections
The threaded fittings, unions, and flexible connectors in a residential gas supply system can develop leaks over time. Older iron or steel gas lines, which were common in Indiana homes built before the 1970s, develop corrosion that eventually compromises joint integrity. Flexible gas connectors, the corrugated metal connectors between the supply line and individual appliances, have a finite service life and should be replaced when appliances are replaced or every 10 to 15 years in normal circumstances.
Improper Installation or Self-Service on Gas Appliances
Gas line work in Indiana requires a licensed plumber for residential applications. Homeowners who attempt to move, replace, or reconnect gas appliances themselves without a license may create connection points that appear secure but are not properly sealed or torqued. Indiana Plumbing License PC11500008 covers residential gas appliance connection work, and Thornton recommends that all gas appliance installations and reconnections be performed by a licensed plumber.
Physical Damage From Flooding or Soil Movement
The historic White River flooding affecting Noblesville and Hamilton County in August 2026 created conditions that can contribute to gas leak development. Saturated soil shifts and settles differently than dry soil, applying stress to underground gas service lines and to the connections where lines enter the home. Basement flooding can physically displace appliances and stress the flexible connectors serving furnaces, water heaters, and ranges. Thornton recommends that homeowners with flooded basements have their gas appliance connections inspected as part of the post-flood evaluation, particularly for appliances that were moved or shifted during the flooding event.
Rodents and Pests
In rare cases, rodents that nest in basement or crawl space areas can damage the outer sheathing of flexible gas connectors or compromise insulation on gas line components. This type of damage is more common in homes that are unoccupied for extended periods or that have known pest activity in mechanical areas. Annual inspection of gas connections is a reasonable maintenance step for homes in established Noblesville neighborhoods with mature trees and wildlife corridors.
How Licensed Plumbers Detect Gas Leaks
After the gas utility has responded and determined the supply situation, a licensed plumber uses a systematic approach to locate the specific source of a gas leak.
Combustible Gas Detection Instruments
Licensed plumbers use electronic combustible gas detectors that sense the presence of natural gas or propane at concentrations well below what the human nose can reliably detect. The instrument produces an audible alert that increases in frequency as it approaches a higher concentration of gas, allowing the technician to trace the leak to its source along the line from the meter into the home and at each appliance connection.
Soapy Solution Testing
At suspected connection points, a soapy solution applied to fittings and connections produces visible bubbling wherever gas is escaping. This method is used to confirm specific leak locations identified by the detector and provides a visual demonstration of the leak that can be documented for insurance or documentation purposes.
Pressure Testing
After a repair is completed, the gas line is pressure tested before service is restored. A licensed plumber isolates the repaired section, applies a test pressure, and monitors for pressure drop over a defined period. A line that holds pressure throughout the test period confirms the repair is complete and the line is sealed before gas supply is restored and appliances are relighted.
Gas Leaks and the August 2026 Noblesville Flooding
The historic White River flooding that set a 100-year record crest at Noblesville in August 2026 created specific conditions relevant to gas leak risk. Extensive soil saturation across Hamilton County caused ground movement and settling around underground gas service lines. Basement flooding displaced appliances and stressed flexible gas connectors in homes throughout the area. Citizens Energy Group, the primary gas utility serving Noblesville, responded to numerous gas-related calls following the flooding event.
Homeowners who experienced basement flooding and have gas appliances in the basement, including furnaces and water heaters, should have those appliance connections evaluated as part of the post-flood professional inspection. Thornton’s gas leak detection service includes evaluation of all gas connections in the home as well as the specific connections at each gas appliance.
Frequently Asked Questions
How do I know if I have a gas leak in my home?
The most common indicator is a rotten egg or sulfur smell, which comes from the mercaptan odorant added to natural gas specifically so leaks can be detected. Other indicators include a hissing or whistling sound near a gas line or appliance, dead or discolored vegetation in a patch over an underground gas line, bubbling in puddles or wet soil over buried gas lines, and in some cases an unexplained increase in the gas bill. Physical symptoms like headaches, nausea, lightheadedness, and eye or throat irritation that appear when inside the home and clear when outside can also indicate a combustion or gas issue.
What should I do first if I smell gas in my house?
Leave the home immediately. Do not flip any light switches, do not unplug any appliances, do not use the phone inside the home, and do not open windows in an attempt to air out the space. Once you are outside and away from the building, call 911 first. Then call the gas utility company. Then call Thornton at 317-697-9265 for licensed gas leak detection and repair service. Do not re-enter the home until the gas utility has confirmed it is safe to do so.
Why is it important not to flip any switches when you smell gas?
Even a small electrical spark from a light switch, an outlet, a thermostat activating, or an appliance turning on can ignite gas that has accumulated in an enclosed space. The concentration of gas needed to ignite is lower than most people assume. Any electrical arc, including those produced by routine switch operation, represents a potential ignition source in a space where gas is present. This is why the correct response is to leave immediately without touching any electrical devices.
Can I open windows to clear the gas from the house?
Ventilating the space by opening windows is not the correct immediate response, because doing so requires re-entering the space and potentially operating window hardware, which creates the delay and exposure time associated with gas accumulation risk. The correct response is to leave immediately and stay outside. The gas utility will ventilate the structure as part of their response once they arrive and confirm it is safe to do so.
Who should I call when I suspect a gas leak?
The sequence is: 911 first (from outside the home), then your gas utility (Citizens Energy Group for most Noblesville addresses), then a licensed plumber for gas leak detection and repair. Do not call anyone from inside the home. Once the gas utility has shut off the supply and confirmed the immediate situation is addressed, a licensed plumber performs the leak detection to find the specific source and completes the repair under the appropriate Indiana trade license.
Is Thornton licensed to detect and repair gas leaks?
Yes. Gas line work for residential plumbing applications is covered under Indiana Plumbing License PC11500008, which Thornton holds as an active and verified license. All gas leak detection and gas line repair work performed by Thornton is done by licensed plumbers under this license. The license is verifiable through the Indiana Professional Licensing Agency.
What causes gas leaks in residential homes?
Common causes include loose or corroded connections at gas appliances including furnaces, water heaters, ranges, and dryers; deterioration of older flexible gas connectors between the gas supply line and appliances; corrosion in older iron or steel gas lines in homes built before the 1960s; physical damage to gas lines from soil movement, basement flooding, or construction activities; and improper installation or self-service on gas appliances by homeowners who are not licensed for gas work. Flooding in particular can displace appliances and stress gas connections.
Can a gas leak have no smell?
Yes, in some circumstances. Natural gas is odorized with mercaptan to make it detectable, but in cases where the odorant has dissipated over a long period in an outdoor buried line, or where the leak is very small and the gas has been diluting into the space over a long period, the smell may be very faint or undetectable without instrumentation. Licensed plumbers use gas leak detection instruments, including combustible gas detectors, to identify leaks that may not produce a strong odor. Relying on smell alone is not a complete leak detection method.
What is mercaptan and why is it added to natural gas?
Mercaptan, also known as methanethiol, is a compound added to natural gas by gas utilities specifically because natural gas in its raw form is odorless. The strong sulfur or rotten egg smell that most people associate with natural gas is entirely from the mercaptan odorant. This additive makes it possible for residents to detect gas leaks through smell, though the concentration needed to smell the odorant is set below the concentration at which natural gas becomes flammable. Propane is also odorized similarly for the same reason.
How do licensed plumbers find a gas leak?
A licensed plumber uses several methods to locate the source of a gas leak. Combustible gas detectors, which are electronic instruments that alert when airborne gas concentration reaches a set threshold, allow the technician to trace the leak to its source along the gas line. The technician may also apply a soapy solution to gas connections to look for bubbling that indicates gas escaping through the connection point. Once the source is located, the supply is confirmed off, the connection or section is repaired, and the line is pressure tested before service is restored.
Can flooding cause gas leaks in Noblesville homes?
Yes. Flooding can cause gas leaks through several mechanisms. The movement of soil during flood saturation can shift underground gas lines and stress their connections. Floodwater entering a basement can physically displace appliances, bending or stressing the flexible connectors that link the gas supply to appliances. Floodwater can also corrode gas connections that were not previously affected by moisture. For this reason, gas appliance connections should be inspected after any significant flooding in the Noblesville area, particularly after events like the August 2026 White River flooding that involved significant soil saturation.
How long does it take to repair a gas leak?
The repair time depends on the location and type of leak. A leaking flexible connector at an appliance can typically be replaced in under an hour once the gas supply is confirmed off and the appliance is accessible. A leaking threaded fitting in a gas line may take slightly longer depending on access. Underground gas line repairs take longer due to excavation requirements. Thornton provides an upfront assessment of the scope and estimated timeline before any repair work begins.
Should I stay out of my home until a plumber confirms there is no gas leak?
Once the gas utility has responded, shut off the supply if needed, and indicated that the immediate situation is resolved, re-entry for evaluation purposes is generally appropriate. However, the gas supply should remain off until the specific source of the leak has been located and repaired by a licensed plumber, and the line has been pressure tested. Re-enabling gas service before a repair is completed and tested is not appropriate.
Do gas detectors or carbon monoxide detectors detect natural gas?
Carbon monoxide detectors do not detect natural gas. Carbon monoxide and natural gas are different substances, and a standard CO detector will not alert to a natural gas leak. There are combination detectors that detect both gases separately. A dedicated natural gas detector uses sensors tuned to the combustible gas spectrum and provides the most reliable detection. Thornton recommends separate detection for both carbon monoxide and combustible gas in homes with gas appliances.
How do I schedule gas leak detection service with Thornton in Noblesville?
For an immediate gas leak concern, follow the steps in this guide: leave the home, call 911, and call your gas utility. Once the immediate situation is addressed, call Thornton at 317-697-9265 for gas leak detection and repair service. Thornton is available 24/7 for gas-related emergencies throughout Noblesville and the surrounding Hamilton County area. For non-emergency gas line evaluation or annual inspection of gas connections, call 317-697-9265 to schedule a service visit.
When to Call Thornton Plumbing HVAC and Electrical
For an immediate gas smell situation, follow the sequence above: leave, call 911, call the gas utility. Once the immediate situation is addressed, call Thornton at 317-697-9265 for gas leak detection and repair. Thornton holds Indiana Plumbing License PC11500008 for residential gas line work, is fully bonded and insured, and is BBB A+ rated since 2006. Thornton is available 24/7 for gas-related emergencies throughout Noblesville, Fishers, Carmel, Westfield, and the surrounding Hamilton County area.
For non-emergency gas line evaluation, proactive inspection of gas connections after flooding, or evaluation of gas appliance connections before the heating season, call 317-697-9265 to schedule a service visit. See Thornton’s full leak detection services for both gas and water leak detection in the Noblesville area. For heating system concerns related to flood damage, see our heating repair services. For related plumbing concerns including water heater connections affected by flooding, explore our plumbing repair and evaluation services for Noblesville and Hamilton County.
