How far does a propane tank need to be from a house?

Under NFPA 58 (the Liquefied Petroleum Gas Code, adopted by virtually all U.S. state fire codes): tanks under 125 gallons water capacity can sit against a building wall, with restrictions on proximity to building openings and ignition sources. Tanks from 125 to 500 gallons must be at least 10 feet from buildings and property lines. Tanks from 501 to 2,000 gallons must be at least 25 feet from buildings and property lines. Underground tanks require 10 feet regardless of size. Additionally, fill valves, relief valve discharges, and vents must be at least 10 feet from any building opening (window, door, vent) or ignition source. Local codes may be stricter. Always confirm requirements with your installer and local fire marshal.

Can I store propane tanks in my garage?

No. DOT propane cylinders should be stored outdoors, upright, in a well-ventilated area on a level, non-combustible surface. Never store them in a garage, basement, enclosed porch, or any interior space. Propane vapor is 1.5 times heavier than air and will pool at ground level in enclosed spaces, creating an invisible layer of flammable gas that can reach an ignition source like a water heater pilot light, electrical switch, or garage door opener. Store cylinders outside, away from building openings and ignition sources.

What should I do if I smell propane gas?

Propane is naturally odorless. A chemical called mercaptan (ethyl mercaptan) is added to give it a distinctive rotten egg or skunk-like odor. If you smell gas: (1) Extinguish all open flames immediately. (2) Do not operate any electrical switches, lights, appliances, telephones, or cell phones, as sparks can trigger ignition. (3) Leave the area and get everyone out of the building. (4) If safely accessible, close the main gas supply valve on the tank by turning it clockwise. (5) From a safe distance, call your propane supplier or 911. (6) Do not re-enter the building until a qualified technician confirms the area is safe.

Does propane produce carbon monoxide?

All fuel-burning appliances, including propane appliances, produce carbon monoxide (CO) as a byproduct of combustion. CO is a colorless, odorless, poisonous gas. Properly functioning, well-ventilated propane appliances produce CO in very small amounts that dissipate safely. The danger arises with incomplete combustion (dirty burners, insufficient oxygen, blocked vents) or indoor use of appliances designed for outdoor use. Generators, camp stoves, and grills must never be used indoors. The CDC recommends placing generators at least 20 feet from any window, door, or vent. Install CO detectors on every level of your home and near sleeping areas.

How do I transport propane tanks safely in my vehicle?

Transport DOT cylinders upright (valve end up), secured so they cannot slide or tip, in a well-ventilated vehicle space. An open truck bed is ideal. If transporting inside a car or SUV, open the windows for ventilation. Close the cylinder valve and install a plug or cap on the outlet if you have one. Do not leave a propane cylinder in a closed vehicle on a hot day. The pressure relief valve can vent propane vapor into the vehicle interior. Transport directly to your destination; do not leave cylinders in the vehicle as an afterthought.

Home Self-reliance Energy Propane Storage and Safety

PROPANE GUIDE

Storage and safety. The rules that protect you.

Propane is one of the safest fuels available when handled properly. The rules exist because the consequences of ignoring them are severe. This page covers placement, storage, transport, leak detection, and carbon monoxide prevention.

NFPA 58 distances Leak detection

PLACEMENT RULES

NFPA 58 siting distances. How far from the house.

NFPA 58, the Liquefied Petroleum Gas Code, is the national baseline for propane tank placement in the United States. It is adopted by reference in virtually all state fire codes.^[1] Your local jurisdiction may impose stricter rules. Always confirm requirements with your installer and local fire marshal before placing a tank.

ASME tank minimum distances from buildings and property lines

Tank size (water capacity)	From buildings	From property lines
Under 125 gallons	0 ft*	0 ft*
125 to 500 gallons	10 ft	10 ft
501 to 2,000 gallons	25 ft	25 ft
Underground (any residential size)	10 ft	10 ft

*Tanks under 125 gallons can sit against a building wall, but fill valves, relief valve discharges, and vent openings must still be at least 10 feet from any building opening (window, door, vent) or ignition source. Source: NFPA 58, as summarized by PERC (Propane Education and Research Council) at propane.com.

Beyond the tank body: additional setback requirements

The distances above apply to the tank shell. Several additional setback rules apply to specific features around the tank:

Fill valve, relief valve, and vents: 10 ft minimum from any building opening or ignition source. This is the rule that catches many installations. A tank can be 10 feet from the house, but if the relief valve faces a basement window 8 feet away, the installation is non-compliant.

Combustible materials: 10 ft clear zone around the tank. No wood piles, dry leaves, brush, or debris within this perimeter.

AC condensers and electrical equipment: Air-conditioning condensers spark internally and qualify as ignition sources under NFPA 58. Typically 3 to 10 ft depending on configuration.

Property lines: Same distances as tank-to-building setbacks. A 500-gallon tank 10 feet from your house but 5 feet from the neighbor's property line is non-compliant.

Why setback distances matter

Propane vapor is approximately 1.5 times heavier than air. A leak from a tank, regulator, or connection does not rise and dissipate. It flows downhill, pools at ground level, and settles into low spots: window wells, stairwells, basements, and crawl spaces. Setback distances exist to keep propane vapor from reaching a building's interior or an ignition source before it dilutes below the flammable range.

The propane industry's safety record is strong precisely because these rules are well-established and widely followed. Incidents nearly always trace back to a distance violation, a damaged connection, or a compromised tank, not to the fuel itself.

PORTABLE CYLINDERS

Storing and transporting DOT cylinders. Outdoors, upright, ventilated.

Storage rules

Always outdoors. Never in a garage, basement, enclosed porch, shed with a sealed door, or any interior space. Propane vapor is heavier than air and pools at floor level in enclosed spaces, creating an invisible flammable layer.
Always upright. DOT cylinders are designed to operate valve-end-up. A cylinder on its side can release liquid propane instead of gas through the relief valve, which vaporizes rapidly and creates a much larger hazard than a gas-phase leak.
On a level, non-combustible surface. Concrete, gravel, or pavers. Not wooden decking.
Away from building openings and ignition sources. Keep cylinders clear of doorways, windows, dryer vents, and AC units. A covered outdoor area with good airflow is ideal.
Valve closed when not in use. Even with OPD protection, close the valve when the cylinder is disconnected from an appliance.

Transport rules

Upright and secured. The cylinder should not be able to slide, roll, or tip during transport. Brace it against the side of the truck bed, strap it to a milk crate, or use a cylinder-specific holder.
Ventilated vehicle space. An open truck bed is ideal. If transporting inside a car, SUV, or van, open the windows. A slow leak in a sealed vehicle fills the cabin with flammable, invisible gas.
Valve closed, cap on. Close the cylinder valve fully and install a plug or cap on the outlet connection if you have one. This protects the valve from impact damage during transport.
Transport directly. Do not leave a propane cylinder in a closed vehicle on a hot day. Rising temperature increases internal pressure. The pressure relief valve can vent propane vapor into the vehicle interior.
Limit: four cylinders per personal vehicle. Federal DOT regulations limit non-commercial transport to approximately 90 pounds of propane without a hazmat placard. That is roughly four 20-pound cylinders.

LEAK DETECTION

Finding leaks. And what to do when you smell gas.

The soapy water test

Mix a 50/50 solution of dish soap and water. With the cylinder connected and the valve open, brush the solution onto every connection point: the valve outlet, the regulator inlet and outlet, every hose fitting, and any threaded joint. If bubbles form, gas is escaping at that connection. Tighten the fitting and retest. If bubbles persist, replace the fitting or hose.

Run this test whenever you connect a cylinder to an appliance, after replacing a regulator or hose, and at least once per season on any system that stays connected (like a grill or a permanent outdoor cooker).

For ASME tank systems, your propane supplier typically performs a full leak check during scheduled fills and after any service work. You can soapy-water-test the accessible connections on your side of the system (from the second-stage regulator to the appliance) yourself.

Recognizing a leak

The smell. Propane is naturally odorless. A chemical called mercaptan (ethyl mercaptan) is added to give it a distinctive rotten egg or skunk-like odor. Any whiff of this smell near a tank, connection, or appliance means propane is escaping.

Dead vegetation. A slow underground leak from a buried ASME tank or supply line can kill vegetation above it. A circular patch of dead grass near your tank line is worth investigating.

Hissing. An audible hiss from a tank valve, regulator, or fitting indicates a significant leak. Do not try to tighten it while gas is flowing. Close the tank valve first.

Frost on a connection. Propane vaporizes at -44°F. A rapid leak can cause localized frost on the fitting or hose where propane is escaping and expanding. Frost on a connection in warm weather is a definitive leak indicator.

If you smell gas: six steps

1. No flames or sparks. Extinguish all smoking materials and open flames immediately. Do not operate electrical switches, lights, appliances, telephones, or cell phones. A spark from any of these can ignite propane vapor.

2. Leave the area. Get everyone out of the building or area where you smell gas. Do not search for the source of the leak.

3. Close the tank valve. If the tank is safely accessible without re-entering the building, close the main gas supply valve by turning it clockwise.

4. Call from a safe distance. From a neighbor's home or at least 300 feet away, call your propane supplier. If you cannot reach them, call 911 or your local fire department.

5. Do not return. Stay away from the building until your propane supplier, fire department, or a qualified technician confirms it is safe.

6. Get the system checked. Before using any propane appliance again, have a qualified technician inspect the entire system and confirm it is leak-free.

Source: Propane Education and Research Council (PERC) gas leak response protocol, consistent with NFPA 58 and state fire marshal guidance.

CARBON MONOXIDE

CO prevention. The invisible risk with every fuel.

Carbon monoxide is not a propane-specific problem. It is a combustion problem. Every fuel, including propane, natural gas, gasoline, diesel, wood, and charcoal, produces CO when burned. The danger is not the fuel. The danger is burning any fuel without adequate ventilation.^[2]

The rules for propane and CO

Generators: outdoors only, 20+ feet from any window, door, or vent. This is the CDC's recommendation and the single most important CO rule during a power outage.^[3] Opening windows or using fans does not make indoor generator use safe.
Camp stoves and grills: outdoor appliances only. Never use a camp stove, charcoal grill, or propane grill indoors for cooking or heating, even during an outage.
Indoor propane heaters: follow the manufacturer's ventilation requirements. Some portable propane heaters are rated for indoor use with specific room-size minimums and ventilation requirements. Read and follow them. A heater rated for 200 sq ft in a 100 sq ft room with the door closed is not "close enough."
Vented appliances: keep vents clear. Propane furnaces, water heaters, and direct-vent wall heaters exhaust CO through a flue or vent pipe. Blocked vents (debris, snow, ice, bird nests) redirect CO into the living space.

CO detectors

Carbon monoxide is colorless, odorless, and tasteless. You cannot detect it without a CO detector. The symptoms of CO poisoning (headache, dizziness, nausea, confusion) mimic the flu and are easily dismissed, especially during winter when flu is common.

Install CO detectors on every level of your home and near sleeping areas. Battery-powered or battery-backup models continue to function during a power outage, which is exactly when the risk of CO exposure is highest (generators running, portable heaters in use, normal ventilation patterns disrupted).

If a CO detector alarms: get everyone outside into fresh air immediately, call 911, and do not re-enter the building until emergency responders clear it. If anyone shows symptoms (headache, dizziness, nausea), tell the responding paramedics. CO poisoning is treatable, but only if recognized.

Signs of incomplete combustion

A propane flame should burn blue. Yellow or orange flames on a burner that normally burns blue indicate incomplete combustion, which produces elevated CO. Causes include dirty burner ports, incorrect gas pressure, and insufficient air supply. Have a technician inspect and clean any appliance showing persistent yellow flames.

ONGOING SAFETY

Seasonal checks and good habits. A few minutes twice a year.

Before heating season (fall)

Check all connections with the soapy water test.
Inspect hoses and regulators for cracking, discoloration, or brittleness. Replace any that show wear.
Clear the 10-foot perimeter around ASME tanks of leaves, brush, and debris.
Verify all exhaust vents on propane furnaces and water heaters are clear.
Test CO detectors and replace batteries.
Weigh backup DOT cylinders to confirm fuel levels.
Check requalification dates on DOT cylinders.

After heating season (spring)

Schedule an ASME tank fill before summer pricing kicks in (propane is typically cheaper in spring and summer).
Visually inspect ASME tanks for paint deterioration and surface rust, especially on the bottom where moisture collects.
Check that the float gauge on ASME tanks is reading correctly (compare to the delivery ticket from the last fill).
Refill any DOT cylinders that ran low during winter.
Inspect outdoor cooking and heating equipment connections.
Ensure the access path to your ASME tank is clear for the delivery truck.

SOURCES

NFPA 58: Liquefied Petroleum Gas Code. Adopted by reference in IRC 2024 Section M2205 and in virtually all U.S. state fire codes. Siting distances summarized by PERC (Propane Education and Research Council) at propane.com.
CDC/NIOSH Toolbox Talk: Carbon Monoxide Poisoning (2017). All fuels, including propane, produce carbon monoxide as a byproduct of combustion.
CDC: Carbon Monoxide Hazard (stacks.cdc.gov/view/cdc/41640). Generators must be used outdoors, at least 20 feet from any window, door, or vent.

Propane guides