Identifying growth opportunities & avoiding low ceilings - septic industry

I'm currently searching for a septic business to acquire (pumping/installs/maintenance/etc.). Curious if anyone on here has had experience acquiring businesses in this space. I'm most concerned with identifying growth potential - these markets seem very fragmented without many larger players.. wondering if this is due to any less-obvious major growth inhibitors (outside of things like capital needs for equipment.. hiring challenges, etc.)? Would love to hear of any experiences in this space.. plumbing & hvac seems to be a good comparison - what are the growth ops you look for? How do you figure out if there's a low ceiling?