Larry, we are having a new home built out in the country and had the same question. Our plumber recommends we install a separate 'daylight' drain so the back wash can drain out into the field rather than into the septic system. Do not imagine brine will help the organisims that are needed to keep the septic system 'healthy'. Suggest you see about a separate drain also. We did install the extra drain before the basement floor has been poured.

LDoyle, when you say "drain into the field", does that mean it goes to the drain field, bypassing the tank, or does that mean it simply gets routed outdoors?
I'm asking because I read a book from the library about septic systems that suggested running wash water outside, not through the septic system at all.
When I checked further, I found that it's illegal to do that where I live.

Yes, I meant just into the field, not the leach field. It's legal here but you should check. It' not 'gray water' like from your washer.

I have a situation where an outdoor water softener was installed 2 1/2 years ago, draining directly to the ground by the side of the house outside. Turns out it was draining over a nearby underground metal storm drain pipe, which is now completely corroded - with a huge sink hole.

1) Is the culprit the water softener salt/sodium or the just the age of the 30-year-old pipe?

2) You mentioned that it was legal or illegal in a certain areas to drain directly to the ground. Specifically where can I find this information for my local area?

THANKS!

Janet