Infrared thermography, IR, allows you to see inside your PVC drain lines. IR cameras see light which has a longer wavelength and a lower frequency than visible light so you can see temperature differences not visible to the naked eye. By doing an infrared scan on the drain line you can find the anomalies which can help solve a problem. The drain line has a clog about 12 feet from the sink and the plumber “snaked” the pipe for 10 feet and said that it was fixed. The drain still did not work and another plumber was called to correct the clogged drain. Do you need your drain lines scanned?