@Suanne & gail I had some trouble with my septic tank due to the laundry detergent going into it. I found some info on this tiopic here
What Are the Beneficial or Detrimental Effects of Additives From Various Research Studies Conducted?
The beneficial effects of biological additives on the septic system are still being debated, but two benefits may ultimately be identified. Based on available literature, enzymatic products might have the ability to reduce the amount of oil and grease in the septic tank. Second, under septic tank bacterial “die-off” conditions, slight reductions in the amount of effluent solids have been achieved by using additives.
A research study by Mark Gross, Ph.D. has shown that septic tank “die off” conditions occur when the bacteria in a septic tank are destroyed due to the presence of toxic substances. Die-off conditions were observed when adding a concentration of 1.85 gallons of liquid bleach, 5.0 gallons of liquid Lysol cleaner, or 11.3 grams of Drano drain cleaner to a standard 1,000-gallon septic tank. Other factors that can cause die-off include the use of anti-bacterial agents, and, in certain cases, medications taken by the home-owner.