Sudden change in well water quality

[DrW]

My well has provided wonderfully sweet water for 20 years. Suddenly, on Thanksgiving Day, the hardness went from 137 mg (in the water in the pitcher in my fridge from the previous week) to 547 mg. The dishwasher suddenly no longer cleans dishes, and the water tastes bad.
Chlorides test high at 680 mg/L
Nitrate-N is high at 12.6 mg/L
pH is low, at 6.1
Sodium is high at 209.

The well is far from the road, and there had been no road salting prior to the change in water quality.
Water softeners will not work well, given the high sodium and chloride levels, and treatment options I have looked at are all very expensive. What would cause a situation like this? What work-arounds are there?
Thanks.

 

[Valveman]

Changing all of a sudden could be a well problem. A hole or break in the casing can let water in the well from a different strata or zone.

 

[Sponsor]

 

[LLigetfa]

As Cary mentioned, a casing failure could account for the change. Possibly some seismic activity affected the aquifer? I don't know if there is any shale gas fracking in your area.