I work for a leak detection company. My co-worker had a job at a commercial building suite for an ice cream shop. meter showing flow with no usage and high-water bill reason we were called. Issue turned out to be due to a hidden cold water line plumbed underground to a floor drain trap. Inside finished wall near floor drain we think there is a valve of some kind that has failed. Putting pressurized air in line bubbled out drain, and microphone testing audibly verified valve in wall. Electric line trace also confirmed path of line. If anyone knows what this line is for, please let me know, we can't figure it out. I have seen trap fill lines in some restaurants before, however only above directly into drain, and any valve exposed for manual activation. I'm stumped as to what function this line and valve device serve. I appreciate any thoughts, Thanks.

It's a trap primer and there's a valve somewhere that is bad and allowing water to continuously flow.
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could be part of a trap primer system, which keeps water in the drain trap to prevent sewer gases from coming up. Typically, these systems are installed above the drain, but it’s possible this one was plumbed differently or hidden for aesthetic reasons. If the valve has failed, it may be stuck open, allowing continuous water flow. You might need to check for a replacement valve if that’s the issue.