I would not put the water in your septic System. I just had my 1000 gal septic tank pumped, at the tune of $800 bucks, With 3 girls in the house a 240 that I do weekly water changes, waste water from RO, bath's ,clothes washing, dishes I was just putting too much water in the system to allow the bacteria to mutiply to the point where every think was breaking down Per the septic pump guy. So you should try to pump/dump it outside in an area where you are not concerned with the grass or flowers.