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Gas systems

Find out more about PG&E's gas safety programs & natural gas system

PG&E is committed to the safety of the communities it serves and is working every day to enhance gas pipeline safety throughout northern and central California.

Automated safety valve upgrades

Valve automation improves PG&E's ability to quickly shut off the flow of gas in the event of a significant change in pressure.


PG&E regularly surveys its 70,000-square mile service area by foot, vehicle, air and even by boat.

High-tech gas tools

Building on its efforts to enhance pipeline safety, PG&E has been an industry leader in supporting new technology.

Learn about our system and how we keep it safe

Natural gas is a key energy source in California. Understand how we provide natural gas, and how gas pipeline safety is our top priority.

Learn how we keep our system safe

We have a full survey and monitoring program to help ensure the safety of our natural gas transmission pipeline system. Learn more about the actions we take to keep you and your community safe. Visit Pipeline Safety.

We're planning to conduct hydrostatic pressure tests throughout our natural gas pipeline system. Learn more about the tests.

Discover how our system works

Spanning our 70,000 square-mile service area, our natural gas system includes approximately 50,000 miles of natural gas pipeline. Natural gas is typically a main energy source for heating and cooking. Get an overview of our system.

View frequently asked questions (FAQ) about our natural gas system

Get answers to typical questions about natural gas systems.

Locate natural gas pipelines near you

Learn more about our natural gas system, and use our interactive map to find pipelines near you.

View our Gas Operations Improvement report

View the progress we're making to become the safest, most reliable gas company in the country.

Find out about pipeline safety and operations


Our gas pipelines deliver natural gas to your household. Get the answers to your questions about our systems.

View FAQ about general pipeline safety.

Discover how we keep our natural gas pipelines safe.

Many homes and businesses are served directly by small-diameter gas pipelines. For security reasons, these pipelines cannot be displayed on an online map. Before you begin any digging or excavation project, we encourage you to call 8-1-1. The 8-1-1 line is a free service that marks underground facilities near you.

Use our online map for information about larger-diameter transmission pipelines. Visit Gas Transmission Pipelines.

You can also contact us to learn more.

PG&E has a comprehensive inspection and monitoring program to address the safety of our natural gas transmission pipeline system. We regularly conduct leak inspections, surveys and patrols of all of our natural gas transmission pipelines. We immediately address any issues identified as threats to public safety. We monitor our gas pipeline system operations 24 hours a day, seven days a week.

If you want additional information about the pipelines nearest you, contact us.

We work with regulatory agencies that oversee our transmission systems. The groups recommend how to keep our natural gas systems safe. The agencies include:


  • The California Public Utilities Commission (CPUC)
  • The U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA)
  • The National Transportation Safety Board (NTSB)

Our combined work aids us in reviewing our records, and in monitoring, surveying and testing pipelines throughout our entire natural gas pipeline system. Our top priority is the safety of our natural gas system.

We've taken significant actions to improve the safety and operations of our natural gas system. We strive to keep you and the communities we serve safe. Our actions included:

  • Completing seven of the safety actions recommended by the NTSB
  • Validating the maximum allowable operating pressure for all 6,750 miles of gas transmission pipelines
  •  Converting more than 3.7 million paper records going back 50 years. We added the records to our new Geographic Information System (GIS) so field technicians have improved access to data
  • Strength testing or validating prior strength testing of 456 miles of transmission pipeline
  • Replacing 55 miles of pipeline
  • Retrofitting 78 miles of pipeline to allow in-line inspections
  • Automating 76 valves
  • Performing in-line inspection of 39 miles of transmission pipe
  •  Improving leak response time from fourth quartile to first quartile nationally
  • Partnering with first responders and public safety officials to enhance emergency preparedness training programs
  • Conducting more than 300 workshops with first responders
  • Adding six new Mobile Command Center vehicles to our fleet. We packed the vehicles with the tools that crews need to address emergencies in the field

After the September 2010 San Bruno pipeline accident, we substantially reduced the pressure on pipelines that had segments with characteristics similar to the pipeline that ruptured. This was performed as a precautionary step until we can confirm the safety of the pipelines.

Remember the following important information:

  • Know the signs of natural gas trouble by smell, sight or sound.
  • Know what to do in case of an emergency, that is, always leave the area, call 9-1-1 and call PG&E at 1-800-743-5000.
  • Know what's underneath you before you dig. Call 8-1-1 for free underground utility marking service.

For safety reasons, we add a sulfur-like, "rotten egg" smell to natural gas. When you smell the odor:


  • Keep a flashlight around for investigating minor gas odors.
  • Don't use matches or candles to find gas leaks.
  • Never turn an electric switch on or off when you suspect a gas leak. The spark can ignite the gas.
  •  Check whether pilot lights are lit.
  •  If the smell of gas persists, or you have any doubts, open windows and doors and get everyone out of the building.
  • Use a phone that is away from the building. Call 9-1-1 and

View FAQ about our survey, inspection and testing techniques.

Discover how we survey, inspect and test our natural gas pipelines.

We regularly leak survey and patrol all of our pipelines. We try to identify signs of damage, soil erosion and other concerns that can affect the safety of the line. We also use cathodic protection systems to prevent corrosion.

We follow even stricter safety standards on our larger-diameter transmission pipelines,. We inspect and test larger-diameter transmission pipelines using a variety of methods. The methods include pipeline devices equipped with sensors and cameras that travel the length of a pipeline. One such device, known as a "smart pig," performs in-line inspections. We also conduct hydrostatic pressure testing. This variant of testing involves charging the pipe with water at high pressures to safely reveal potential weaknesses. We can also dig up the pipelines to directly assess them.

Direct assessment is an effective technique for identifying potential coating damage. Coating is the first level of protection against lead-inducing external corrosion. This technology also assesses the current level of cathodic protection, which helps show the current and future health of the pipe. Direct assessment can be performed on nearly any pipeline, regardless of its diameter or configuration.

Leak surveys help us identify problems in a gas transmission pipeline. The problems can affect the integrity of the pipe or the operation of the transmission system. Leak surveys involve a variety of technologies, ranging from combustible gas indicators to newer infrared and laser devices.

Many internal line inspection, or in-line inspection (ILI) devices are available. The devices can be equipped with robotic cameras and sensors to check pipe thickness and welds while detecting flaws and corrosion. Although smart pigs are effective, their use is limited to certain types of pipes. Many of our pipelines were designed and constructed before smart pig technology was developed. Some of our pipelines require significant reconstruction to accommodate this form of inspection.

Hydrostatic testing involves water-pressure testing a pipeline. It's a proven method of verifying the actual capability of a natural gas pipeline. We want our system to operate at a safe level of pressure. Hydrostatic testing is also used to test such familiar items as scuba tanks, fire extinguishers and air compressor tanks.

A hydrostatic test involves pressurizing a section of pipe with water. The pressure is tested at a higher percentage of the pipe material's maximum design strength for natural gas. This verifies the capability of a pipeline to safely operate at the desired level or pressure. The test can also reveal weaknesses that can lead to defects and leaks in the pipe. To perform a hydrostatic test, the pipeline must be taken out of service for many days.

View FAQ about general gas system operations. 

Learn how we run general operations for our natural gas systems.

Transmission pipelines are generally larger and operate at a higher pressure than distribution pipelines. Transmission pipelines move natural gas from compressor stations and storage facilities to regulators. Regulators reduce the pressure before reaching the distribution system. The distribution system feeds the smaller lines that deliver gas to your business or home.

Our transmission pipelines typically operate at roughly 60 pounds per square inch gauge (psig). Learn more about our gas transmission pipelines in your area from our interactive map. Visit Gas Transmission Pipelines.

A properly maintained pipe can operate safely for 100 years or more. Pipeline age is a factor, but not the only factor that we consider when we inspect our pipelines.

Federal law requires that we establish MAOP for all pipeline systems. MAOP allows for a wide margin of safety. The MAOP is a fraction of the pipe's actual calculated strength. Pipes and pipelines typically operate well below the MAOP.

MAOP is determined in one of three ways:

  • Calculating the Specified Minimum Yield Strength (SMYS) of the pipe. SMYS is the minimum pressure at which the pipe is expected to begin deforming. MAOP is then set at a fraction of the SMYS, allowing for a wide margin of safety.
  • Basing it on pressure tests. MAOP is set safely below the pressures used in the pressure test.
  • Basing it on the pressure at which the pipeline has operated safely for years (for pipe installed years ago).

Federal law requires that pipeline operators establish MAOP for each section of pipeline or each distinct segment of our gas pipeline system.

PG&E controls pressure on our pipeline system through a series of safety measures, including pressure regulator stations and overpressure protection devices. The systems operate to keep pressure within specified limits. They are surveyed and maintained regularly. Learn more about how our natural gas system operates. Visit Natural Gas System Overview.

We have hundreds of automatic over-pressure protection control valves. The valves protect pipelines and are activated when the pressure gets too high. We also have some lines with rupture-control valves for specific needs. Our 24-hour Gas Control Center has the ability to shut down some pipeline systems via remote control.

The valves that we use differ in the following ways:

  • Manual valves can be operated only by a trained, federally qualified individual at the valve location. The valves are hand-operated by wheel or gear assemblies. A technician can also use a wrench to open a valve. An indicator shows whether the valve is open or closed.
  • Automatic shut-off valves are fully automated. Automatic valves don’t require remote control or on-site operation. Human intervention isn’t needed with automatic shut-off valves when certain pipeline conditions arise.
  • Remote-controlled valves can be operated from an off-site location. We control the valves from our 24-hour staffed Gas Control Center.

View FAQ about earthquake concerns.

Discover how we plan to protect our natural gas system during earthquakes.

Gas transmission pipelines are generally resistant to earthquake damage. We expect our pipelines to continue working after earthquakes occur. In locations where there is believed to be a greater risk of pipeline failure from an earthquake, we work to manage the risk of damage to the pipeline. We're also replacing some pipeline sections with a design that is more earthquake-resistant.

PG&E immediately walks the system after an earthquake occurs. Shortly thereafter, we evaluate the lines by helicopter. The inspections help us confidently determine whether our system has been damaged.

View FAQ about how PG&E trains and collaborates with first responders.

PG&E works with first responders to foster early response safety. Learn howwe coordinate with them.

We work with external partners such as first responders and public safety officials. Our goal is to enhance training for emergency preparedness and response. Enhanced emergency prevention, preparedness and response programs consist of education programs. The programs are designed for first responders, contractors, infrastructure departments, community members, schoolchildren and other stakeholders.

We created educational programs with the following objectives:

  • Increase educational and interactive sessions with first responders to meet demand
  • Develop a contact list for all local first responders
  • Launch a first responder website portal
  • Conduct a joint California Independent System Operator (CAISO) and CPUC gas curtailment exercise, such as the one held on August 12, 2011
  • Provide maps, GIS data and other information to first responders
  • Conduct Incident Command System (ICS) training
  • Launch first responder workshops, such as the one launched in the fourth quarter of 2011
  • Provide a first responder online portal for training material downloads
  • Schedule our representatives to deliver onsite training, such as the training delivered in the first quarter of 2012

PG&E wants to create an emergency response plan that incorporates learning from prior experience and industry benchmarks. A coordinated plan can help ensure that emergency response preparedness is embedded in our operations.

We expect the following benefits from our safety programs:


  • Fewer preventable incidents
  • More-informed and safer citizens
  • Improved coordination during emergencies
  • Faster restoration times following an incident
  • Line-of-sight accountability for prevention, preparedness and response performance


View FAQ about our class location report.

Learn about our system-wide gas pipeline class location study.

We're conducting a full review of our gas operations to improve our performance. PG&E is striving to bring our system to industry-leading levels. We initiated this review following a CPUC request. The result is the implementation of a new procedure that calls for annual class reviews.

The pipelines are rated through federal and state regulations. The class designation of a pipeline is based on the types of buildings, population density or level of human activity near the segment of pipeline. This classification determines the pipeline's MAOP.

Pipelines are rated by the following four classes based on population:


  • Class 1. Up to 10 residences or businesses per mile of pipeline
  • Class 2. 11 or more residences or businesses per mile
  • Class 3. 46 or more residences or businesses per mile
  • Class 4. Urban areas with buildings of four or more stories





The review indicated that some segments of pipe have a MAOP higher than appropriate for the current class location. As a result, PG&E identified 7.5 miles of pipeline where we must reduce operating pressure. The length of the pipeline consists of multiple shorter segments in our service area.

We already completed pressure reduction on approximately 3.5 miles of pipelines. We're continuing to lower the pressure on the other 4 miles. The effort involves more than 30 different locations. We’re carefully planning how to lower the pressure to ensure safety.

We're still evaluating location data and operating pressures for approximately 100 miles of pipeline. We’re trying to complete the work as quickly as possible.

Safety is our top priority. We're verifying that operating pressure on all of our lines is appropriate for each location. Where necessary, we’re lowering the pressure.

We're continuing our engineering work and field upgrades of our newly classified segments. We’re bringing our system back up to the operating pressures needed, providing longer-term reliability.

View FAQ about the PG&E Pipeline Safety Enhancement Plan.

Find out more about our plan to enhance the PG&E natural gas pipeline system.

The PG&E Pipeline Safety Enhancement Plan can allow us to:

  • Replace more than 180 miles of pipeline.
  • Strength test more than 780 miles.
  • Retrofit about 200 miles to accommodate in-line inspections.
  • Perform more than 200 miles of in-line inspection.

The PG&E Pipeline Safety Enhancement Plan was developed in response to the CPUC decision concerning new pipeline safety regulations. We plan to implement any new CPUC rules and regulations that it adopts.

The CPUC ordered California gas utilities to file implementation plans in June 2011. Before that date, PG&E already started taking action to fix our gas transmission pipelines. The steps were all taken prior to the CPUC order, and we're continuing the work today.

No, the plan represents only part of our overall plan to enhance gas transmission safety. We're improving our overall gas operations by strength testing or replacing all pre-1970's pipelines. The plan also includes:


  • Installation of automatic shut-off valves
  • Improvements in recordkeeping
  • Interim safety measures
  • Emergency response procedures

PG&E created a separate operating unit for our gas operations. The team is led by a gas operations expert who brings 30 years of experience in improving some of the nation's oldest gas systems. We're also implementing broad changes across the company to increase public safety.

The Pipeline Safety Enhancement Plan reflects new regulatory requirements. The requirements establish a known margin of safety across our gas transmission system. The plan incorporates the following considerations:


  • Lessons from the San Bruno accident
  • NTSB recommendations
  • Independent review panel findings
  • Industry benchmarking

Our plan also considers feedback from key regulators, industry experts, utilities and other interested parties.

The pressure testing and replacement work can be conducted in a manner that helps ensure the safety of the surrounding community. Our customer outreach plan is designed to provide the following information:


  • When the work is scheduled
  • What work we’re doing
  • What to expect in terms of test length, impact to service and access restrictions

In certain limited cases, we may have to close streets or ask customers to vacate their homes while a test is conducted. Our customer outreach efforts are designed to minimize inconvenience. We want to provide clear information so that customers and the community know what to expect.

The PG&E plan proposes to automate 228 valves in Phase 1.

Approximately 60 percent of automation miles can be installed on pipelines located in the Bay Area. In 2011, we automated 29 valves on the San Francisco Peninsula.

Automatic valves have the following benefits:

  • Shutting off gas pipelines quickly
  • Isolating a segment of pipeline if it ruptures
  • Facilitating an emergency response
  • Reducing potential threats to the public and property
  • Minimizing property damage
  • Minimizing the quantity of gas released during a pipeline rupture
  • Reducing the environmental impact of gas leaks

A typical residential customer might have an average monthly gas bill increase of $1.93, from $45.23 to $47.16. A typical small business customer might have an average monthly bill increase of $14.96, from $279.80 to $294.75.

Discover other gas system resources


Contact us with more questions.


The American Gas Association also provides FAQ. Download Get The Facts: Pipeline Safety (PDF, 67 KB) .

Learn where natural gas pipelines are located


PG&E monitors our natural gas system status in real time on a 24-hour basis. We regularly conduct leak inspections, surveys and patrols of all of our natural gas transmission pipelines. We immediately address any issues that are identified as threats to public safety.


The following interactive map shows pipelines in your neighborhood.


NOTE: Internet Explorer is not supported for this application.


PLEASE NOTE: Gas transmission pipeline data is provided by the PG&E Geographic Information System. Street map info is provided by Esri®. PG&E is providing this map as a courtesy and for general information purposes only. The map does not represent that the information contained herein is accurate for any particular purpose, and therefore disclaims all warranties, expressed or implied, including the warranty of fitness for a particular purpose. Independent verification from experts can be obtained prior to any specific use. Recipient accepts full responsibility for any consequences associated with use of this information.

Contact us

For more information, contact us.


View gas safety resources

We have a complete inspection and monitoring program. The program helps ensure the safety of our natural gas transmission pipeline system. Learn about our plan for safer, more reliable gas service from the following resources:


Discover the basics of our system by the numbers


The PG&E natural gas system spans central and northern California. Our service area stretches from Eureka in the North to Bakersfield in the South and from the Pacific Ocean in the west to the Sierra Nevada in the east.


Natural gas is a key energy source for customers in California. In most major cities in the United States, natural gas is the clean fuel of choice for heating and cooking.


We've made it our responsibility to deliver safe, reliable and affordable natural gas.


The following figures provide details about our system:


  • More than 70,000. The total square miles of our service area.
  • 42,000. The length in miles of our gas distribution pipelines.
  • 6,700. The length in miles of our gas transmission pipelines.
  • 15 million. The number of people to whom we provide gas and electric energy.
  • 1 out of 20. The number of Americans to whom we serve gas and electric energy.
  • 15. The number of times our natural gas system can run from California to Boston, based on total miles.
  • 970 billion. The amount of natural gas in cubic feet that we provide per year. This amount equates to roughly 2.6 billion cubic feet per day.
  • 833. The number of vehicles in our fleet fueled by natural gas; 272 are dedicated natural gas vehicles.
  • 27 percent. The segment that natural gas comprises in our power mix.

View our natural gas pipeline map

Learn more about our natural gas system and use our interactive map to find pipelines near you.


Visit gas transmission pipelines


Find out about regulation

The California Public Utilities Commission (CPUC) regulates privately owned electric, natural gas, telecommunications, water, railroad, rail transit and passenger transportation companies. Learn more about the CPUC.


Visit California Public Utilies Commission (CPUC)

Additional resources


Read more about pipeline inspection, replacement, and safety initiatives

Gas Tools

PG&E is committed to the safety of the communities it serves and is working every day to enhance gas pipeline safety.