I have seen quite a few homes where the iron is in the  ground water , the people have to monthly clean the sump pit with a garden hose .  

If it were ground water, it should be under the plastic.

I thought she was paranoid till later news reports came out about ground water contamination due to several chemical business that since closed.

Groundwater is usually not impacted as you will not know since most tanks are only 4-5 feet deep and you will not encounter groundwater in the tank pit. 

Over time, it rusts out and sand, ground water, mice can get in them.

That's one big reason that the landfills are choked with siding, windows and fencing that risk contaminating ground water.

We knew there was water in the scrawl space, but our initial assumption was it was just groundwater since we’ve had a lot of rain in Maryland and the Annapolis / Baltimore area.What’s actually happening is the water is coming from the front right corner of the house, where the sewer line runs, plus there is a gap in the foundation in that same area that needs to be sealed.

The more suburban expansion in the westward prairies, the less ground-water holding land will be available to absorb water. 

Well during the installation (We had a very WET winter with the snow fall in the winter and rain fall in the spring) the ground water was a lot higher than the engineer expected.

They do wear out.Or a community will be forced to connect to a central facility if there is a pollution problem impacting the ground water.