Some of the replies raised the possiblities of contamination in
reusing the ground water from the sump well. If there are any oils or
fluids from leaks in cars parked in the driveway, they will be washed
away from the foundation of the house. I suspect that most of the
water in the sump during our dry summers was from water that
percolated down to the drain tiles from watering plants near the
house. So reusing that water to water those plants again, or the lawn,
seems okay.

However it does raise a point. How contaiminate free is rain water
that has washed off roofs. I have cedar shingles. Don't they treat
them with fire retardants? I suppose rain water might be fine for
plants or lawns, but if you have a vegetable garden use virgin water
and not rain water or ground water.