Your septic system can be damaged by doing large loads of laundry in a short time. Solid materials from your laundry will settle in the tank. This in turn will cause your septic system to malfunction. The wastewater would flow to the ground. This is why you should never use too much water at once so that your septic system can handle it. Another thing you can do to prevent your septic system from malfunctioning is to regularly have your tank pumped.