How long is a water softner typically take to clean itself out? We have an older one that takes about 3 hours. Also, it is dumped into our sump pump which then runs about every 5 minutes for those 3 hours. This is very annoying at night and it kills the grass. I have a laundry drain for the washing machine right next to it. Would it be possible to dump the water softner into it so that it goes directly into my septic? Will that kill the grass over my leach fields?