I just found this online about CBD detected in a drug screen:

"The question becomes: Can a person consuming only high-CBD, low-THC forms of cannabis test positive for the herb and, thus, lose their job? While many patients certainly want to medicate using a natural, alternative remedy like cannabis, they also can’t afford to lose their income and don’t desire to survive the stigma of being outed for marijuana, still a highly stigmatized substance, especially in conservative states lacking medical cannabis laws.

The short answer: No, one will almost never test positive for CBD oils that contain almost no THC.

What About Heavy Consumers?

There are a few reasons that heavy consumers of CBD oil may initially test positive on a drug screen. Most popular urine tests for cannabis follow the Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines, meaning they will not detect a cannabinoid like CBD because such tests involve very little “cross-reactivity” between THC and other common cannabinoids like CBD, CBG, CBC, and CBN.

However, patients who consume very large quantities of CBD oil, such as 1-2 grams per day, could possibly test positive on an initial urine screening. When an initial test flags positive, a second, more accurate test called a GC/MS is administered to the urine sample to confirm if it is an actual positive for THC (false positives on the first, less stringent test aren’t completely uncommon). Because this second, confirmatory test easily differentiates between THC and CBD, even the heaviest of CBD oil consumers can rest assured that they won’t lose their job because of this alternative treatment for their disease or ailment. As long as they don’t consume THC, that is."

And from the Charlotte's Web web site (the one I'm currently using):

"Cannabinoids are the primary chemical compounds produced by the cannabis plant and there are more than 85 identified cannabinoids. Tetrahydrocannabinol (THC) is the most well known cannabinoid produced by the cannabis plant, and is the ONLY psychoactive cannabinoid. Of the 85+ non-psychoactive cannabinoids, Cannabidiol (CBD) is the most widely known.

Charlotte’s Web™ is a whole plant hemp extract containing the entire range of U.S. Government patented cannabinoids. Charlotte’s Web™ was created using proprietary genetics developed by Colorado’s Stanley brothers. Classified as hemp and thus legal to ship to all 50 states, Charlotte’s Web™ contains THC levels of 0.3% or less. "