Antibacterial soap impacts on septic system?
The quick answer is: Yes, it can cause harm.
Think about it...The septic system (both the tank and your &quot;drain field&quot;) rely on bacteria, and antibacterial soap is not designed to kill only specific species of bacteria. In other words, antibacterial soap can kill a whole range of bacteria, and that certainly includes the bacteria needed in your septic system.
According to University of Arizona Cooperative Extension (Farrell-Poe, 2018):

The use of “antibacterial,” “disinfectant,”or “sanitizing” products in the home can and do destroy both good and bad bacteria in septic treatment systems. “Normal usage” (according to directions) of these products will destroy some beneficial bacteria. Fortunately, the normal bacteria population within the septic system is sufficient and adequate to quickly recover. Significant treatment problems, with conservative use, should not occur. Excessive use of these products in the home can cause significant and even total destruction of the bacteria population. Normally, the use of any single product or single application will not cause major problems.
However, the accumulative affect of using too many such products and excessive application may cause serious problems and damage to the septic system.
It appears that some alternative systems may be more affected by “antibacterial” products than other systems. Additional and more conclusive research is needed.

You can find additional info about antibacterial agents in septic tanks as well as discussion about the effects of the common antibacterial agent, triclosan, on septic tanks here: Svenningsen et al. (2011) and Kirjanova et al. (2014).

 Works cited: 
Farrell-Poe, K., 2018. Antibacterial Products in Septic Systems. The University of Arizona Cooperative Extension fact sheet
Svenningsen, H., Henriksen, T., Priemé, A. and Johnsen, A.R., 2011. Triclosan affects the microbial community in simulated sewage-drain-field soil and slows down xenobiotic degradation. Environmental pollution, 159(6), pp.1599-1605.
Kirjanova, A., Rimeika, M., Vollertsen, J. and Nielsen, A.H., 2014. Retainment of the antimicrobial agent triclosan in a septic tank. Water science and technology, 70(4), pp.586-592.