Doing load after load of laundry could be harmful to your system. This does not allow your septic system time to adequately treat wastes. It will flood the drainfield by not allowing your system enough time to recover. Whenever possible spread the laundry out over the week rather than do it all in one day.
Using a garbage disposal greatly increases the amount of solids and grease entering the septic system. The bacterial action in the tank will break down some of the solids but most of the grindings will have to be pumped out.
Do not flush any bathroom items down the drain. They have no where to go but in the septic tank. They may become trapped somewhere in the system and damage system components. Even toilet paper is best put in a trash can. What you put down your drain can have a major impact on how well your system works.
Flushing household chemicals such as pesticides, paint or antifreeze can stress or destroy the biological treatment that must take place in your system. Usually, the bacteria in your septic system will recover quickly after small amounts of household cleaners, but the smaller the amount the better.