Switch to high-efficiency toilets to reduce household water entering your system. According to the EPA, standard toilets use up to 5 gallons of water per flush, while high-efficiency models only use 1.6 gallons per flush.

Space out your washing machine use throughout the week to prevent overflowing the system. The average washer emits about 40 gallons of water per load. If 6 or 7 loads of laundry are washed back to back that’s 240-280 gallons of water, not including other water usage like bathing, washing dishes etc. that is very likely happening simultaneously.

Fix leaky faucets, pipes, and toilets as soon as possible. According to estimates by the EPA a leaky toilet can waste more than 200 gallons of water in just one day, according to estimates from the EPA. Overloading your system can cause backups and other septic tank failure.
Never pour grease, chemicals, paint etc down the drains.
Never flush feminine hygiene products, pharmaceuticals, cigarette butts, wipes (even flushable wipes), coffee grounds, diapers, cat litter etc. Basically, your septic system is designed to process human waste and to some extent toilet paper. Flushing anything else has the potential to cause thousands of dollars of damage to your system.
If there is a garbage disposal use it sparingly or not at all as they increase BOD (strength of the waste water) within the tank. The higher BOD levels increase the potential of a Bio-mat developing more readily within the drain-field. If a bio-mat develops replacing the drain-field is almost always necessary.
The average septic system is designed to process about 300 gallons per day. The average household member uses 70 gallons per day.