Laundry and septic tanks can work well together. Septic tank systems are something we don't like to think about and usually don't until there is a problem. A septic tank handles all of the waste water from homes that are not connected to a public sewer system.
Laundry contributes a great deal of water to the system and there are a few tips you should follow to prevent problems:
Don't run laundry wastewater directly into the drainfield; it should be run into the septic tank. Soap or detergent scum will plug the soil pores in the drainfield and cause the system to fail.
Normal amounts of detergents and bleaches can be used and won't stop the bacterial action in the septic tank.
Using too much soap or detergent can cause problems with the septic system.
Inexpensive detergents may contain excessive amounts of filler or carrier and some of the fillers can be montmorillonite clay that is used to actually seal soils. The best solution is to use a liquid laundry detergent, which seldom has clogging fillers that may harm a septic system.
Homemade laundry products are safe to use with septic systems because they do not contain fillers.
Here is a list of the best detergents for a septic system.
Specific questions? Just ask here.