If, like me, you're on a septic system, I highly advise you to NOT dump large quantities of salt water down the drain. Salt is corrosive, so all of the hardware related to the septic system will corrode, and it kills off the natural bacteria present that assist in breaking down the waste.
I've got a 15' x 6' semi-circle in front of the carport, enclosed with a plastic retaining strip, covered with pea gravel. Keep a cedar bench there. I dump my salt water there. Kills the weeds that tend to grow through the gravel bed. It did, eventually, kill the two wild rose bushes that were there... this was a good thing, IMHO. Wild roses are near impossible to kill :)
So far, in about 2.5 years worth of having done so, the grass surrounding the gravel still looks fine. Well... not right now, of course, but there isn't much green anywhere at the moment. August in Missouri.