What do the different colored paint and flags mean?

I have little flags and spray paint all over my yard. What do the different colors mean?

After you call Pennsylvania 811 or submit your request online, the important work of marking your digging site begins. Utility companies will send a professional locator to ‘mark’ the site with colored paint, chalk, or flags to indicate the approximate location of the underground utility lines. What do these colors mean?


First, it is important to know that Pennsylvania 811 itself does not mark underground utility lines. That responsibility falls to the company that owns or operates the individual line. For example, if there is an underground natural gas line near your site, the gas company will send a professional locator to mark the site. Similarly, if there is an underground electric line, the electric company will send a representative. This is true for all underground utility lines.

Next, the colors used  are standardized in Pennsylvania, as our state’s law follows the Common Ground Alliance (CGA) Best Practices for Temporary Marking (ANSI standard Z535). This means that there is never any confusion over what each color marking stands for. Whether you’re digging in Erie or all the way across the state in Philadelphia, the color code is the same in every location, every time. Let’s decipher the rainbow of markings that may have just appeared on your lawn so you can truly “know what’s below.”


Pink: Temporary survey markings

If you have had your property surveyed by a professional surveying company, these markings will appear in pink. It’s unlikely that an individual utility will send a surveyor to your property for most types of projects. However, if you see pink markings, know that the site was recently surveyed.


Red: Electric power lines, cables, conduits and lighting cables

We often think of electric power lines as traveling across poles overhead, but many are also buried underground, especially in newer neighborhoods and subdivisions. These are certainly lines you do not want to damage by accident, as striking a power line could cause electrical burns, electrocution, or at the very least, power outages in your area.


Yellow: Gas, oil, steam, petroleum or gaseous materials

Striking these types of lines while digging could be explosive or cause severe burns (in the case of steam, which is under pressure). Entire buildings have been leveled, and people have lost their lives in gas line explosions. So if you see yellow markings, use particular caution to keep yourself, your home, and your neighbors safe from catastrophic harm.

Orange: Communication, alarm or signal lines, cables or conduits and traffic loops

Telephone and fiber optic lines for internet service are common in residential neighborhoods. Or, you may live near a traffic signal whose lines run near your property. Accidentally damaging these lines could result in outages that are costly to repair and threaten safety in your neighborhood.


Blue: Drinking water

These lines supply your home and neighborhood with the water you need to live every day! Striking a water line can cause extensive flooding on your property. Resulting water service outages could also require you to vacate your home until the damage is fixed since you will be unable to cook, flush toilets, shower, or have water to drink.


Purple: Reclaimed water, irrigation, and slurry lines

These types of markings are probably uncommon in most neighborhoods in Pennsylvania since many of us do not have irrigation systems installed in our lawns and typically are not reclaiming water. Still, if you see purple markings, this means water lines are nearby, and accidentally striking one of these could cause flooding that results in expensive cleanup.


Green: Sewer and drain lines

Now we’re talking about lines that would be smelly and generally disgusting to damage! A sewage flood on your property is something that will likely require expensive professional cleanup, and you may have to foot the bill for this kind of damage. If you see green markings, know that sewer lines are nearby and proceed to dig with appropriate caution.


White: Proposed excavation

White marks are used to communicate where the excavation will occur. You are responsible for marking your digging location in white before calling 811, which is an important step to assure that utility lines get marked in the correct place. Use white stakes, white paint (available at a home improvement store), or white flags.


Outlining your proposed excavation area in white helps keep you safe, because the professional locators will know exactly where you will be digging and can spend their time marking the underground utilities near where you will be digging instead of guessing where excavation will take place.

Again, marking in white is your responsibility, or your contractor’s responsibility if you have hired a professional excavator to do the work. If professional locators cannot tell where the digging site is, they may have to come back more than one time, and that means annoying delays for your project schedule. The easiest way to avoid delays and better communicate to locators is to mark the excavation site in white before you call 811.


Common abbreviations seen with the markings

Once your yard is marked, you will notice that locators may have also written seemingly inscrutable codes on the ground in any or all of the colors indicated above. You may now see letters and numbers scribbled all around your property! These abbreviations give more information about what kind of line is underground and who owns or operates the line. The marks should also state how big the line is (diameter). While not standardized like the color coding system, the Common Ground Alliance keeps a listing of common abbreviations to help you determine what exactly is under the ground nearby and what utilities have ownership.



A note on service drops

With all of this marking going on, it’s important to remember that some lines may be in the area that will not be marked by the utility company. These are known as “service drops,” and are lines that YOU actually own as opposed to the utility company. This may be something like the gas line or electrical line that runs directly into your home. Find more information on our How it Works page now. If you happen to see the utility company marking your lines, you may ask that person to mark your service drops as a courtesy to you. But, you are responsible for knowing where these lines are located on your property.

By now, you know how important it is to “dial before you dig” to keep yourself and your neighborhood safe from accidents caused by uninformed digging. If you are planning a digging project and haven’t called 811 yet, get in touch now!