From planting a rose bush to full-scale construction, unplanned digging projects can cause disruption, danger and even death, along with property damage and significant expense. Before you dig, call 811 – the national Call Before You Dig/Miss Utility service that initiates marking underground utility lines.

When you call 811, you are connected to your local One Call Center in the District of Columbia, Maryland or Virginia. Member utilities, such as Washington Gas, are then notified to mark the approximate locations of underground utility lines with high-visibility safety paint and/or flags. The service is free.

Everyone, including homeowners and construction companies, is required by law to call 811 before scheduling any type of digging. This includes general digging, gardening, landscaping, home improvements and/or major construction, excavation or demolition.

Call 811 at least two full business days – excluding weekends and holidays – before you dig.
Homeowners | Contractors

No digging should start until lines are marked or confirmed as “no conflict.” If you are unsure if the underground utilities have been marked, check back with 811 to make certain there are no underground utilities in the digging area.

For free damage prevention training, call the Washington Gas Damage Prevention Helpdesk at 703-750-4588

Mind those marks!

When you call 811, your dig area will be marked with colored flags of spray paint to identify specific types of underground utilities. Know what’s below!


 Red – electric utilities such as cables and power lines (most common flag)


 Yellow – petroleum, steam, gaseous


 Orange – communications (TV cables, signal, alarm lines)


 Blue – water, irrigation, slurry (usually potable drinking water)


 Purple – non-potable water, irrigation


 Green – drains, sewers


 White – planned excavation


 Pink – temporary survey marking

Additional resources
Common Ground Alliance
811 Insert
Maryland Underground Facilities Damage Prevention Authorit

Miss Utility, District of Columbia: 800-257-7777 |
Miss Utility, Maryland: 800-257-7777 |
VA811, Virginia: 800-552-7001 |

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Customer Service 844-WASHGAS