Radon Mitigation System Gauge

If you see one of these you are looking at a part of a Radon mitigation system. Basically a simple system that creates a negative pressure (suction) under the concrete slab floor of a house, or in the case of a crawl space under sealed plastic sheeting covering the dirt or gravel floor.

So you will know that your system is working there is a simple gauge on the pipe going out of the building. Usually in the basement or garage but may be hidden in a closet, this gauge when looked at should have the colored water “higher up” the pipe on the side that has the small tube going into the big pipe. You do not have to worry about the numbers on the gauge, usually about a half inch higher.
In this photo the colored liquid is level: the electric pump/ fan (generally in the attic or on the side of the house) has stopped operating. The system is no longer operational.