Soft water carries the soap residue further because it will mix with the water easier than with hard water. I have learned a lot of this from a friend that is a septic engineer that designs sewage treatment plants all over the country. He started out doing homes, then small communities, and now he does larger projects. One of the problems that I already see within this thread is what I call the "ostrich policy". I haven't had a problem so far, so if I do nothing that is better than doing something, like having the system pumped. You can't hurt your system by having it pumped once a year, you can definitely hurt the system if you don't have it pumped ever. It is like the person that says, why should I drive slower, I haven't gotten caught for speeding in years. The longer you go, the greater the odds of problems. It never ceases to amaze me about how people determine priorities. They will spend $15000 on a tractor and then want to find the cheapest oil or filter for that tractor. There have been times when I will play devils advocate to see who I can draw out of the woods with that type of thinking, but no one ever points out what I have just mentioned. Maintenance doesn't cost, it saves. This principle applies to all aspects of life. If you want to live longer, then take care of your body. If you want the tractor to last, take care of it. Same for the septic system, but unlike the other two examples, the septic system is a "out of sight, out of mind" type of item. If it doesn't stare you in the face every day, you don't think about it.
One final thought, if you have a water softener, then don't put the rinse water into your septic system. I am not certain why, but the local Health District for our area sent out notices a while back indicating that there were a large number of system failures as a result of this practice. They recommended a separate dry well for the water softener discharge water rather than down the septic system drain.
