The invert is the inside bottom of a sewer pipe, and it is the line everything drains along. Slope is measured invert to invert, never from the top of the pipe. When a joint offsets and one invert sits higher than the next, solids catch on that lip. As a result, the clogs keep coming back.
Slope is the whole reason this matters. A sewer line works on gravity alone, and it needs consistent fall from the house to the main. Measuring from the top of the pipe hides a problem, because two pipes of different diameter can line up perfectly on top and still leave a step at the bottom where the water actually runs.
That step is what a camera shows. A quarter inch of offset does not sound like much, but wipes, grease, and root hair all catch on it, and every catch makes the next one easier. A homeowner who snakes the same line every few months is usually looking at an invert problem rather than a habit problem.
North Texas makes this worse. Expansive clay swells when wet and shrinks in drought, and that seasonal movement pushes pipe sections out of alignment over years. Typical offset Nuflow DFW measures on a repeat-clog DFW line, in inches or pipe-wall fractions.
An offset joint does not always need a dig. Where the pipe holds its shape, a liner smooths the transition and removes the catch point. Where one section has dropped badly, that section comes out.
Nuflow DFW is a licensed trenchless sewer contractor serving 25 Dallas-Fort Worth cities, RMP# 46694. Our camera inspection shows the offset and the fall, and you keep the footage. Call (469) 701-0597.