The answer to 'my hydro jetting smells bad' is that a foul odor from hydro jetting is often caused by the buildup of organic matter and bacteria in the sewer line. This can happen when the jetting process dislodges and flushes out significant debris and buildup, which then creates an unpleasant smell. The smell is typically temporary and will dissipate as the line clears and the debris is fully flushed out.
Some common causes of a smelly hydro jetting job include older sewer lines with significant buildup, lines that have not been regularly maintained, or lines that are clogged with grease, food waste, or other organic matter. In some cases, the smell may also be due to the presence of hydrogen sulfide gas, which can have a rotten egg-like odor.