Sounds like you might do better with the ground water and a filtration system.
Chlorine can be a good thing as long as you neutralize it before use. Sodum Thiosulfate or Sodium metabisulfite work every well. And you only add 0.5 to 1 ppm chlorine. Very important with shrimp because over dose will kill the babies.
We chlorinate all our seawater for the shrimp hatchery. The good thing about it is that it oxydizes some of the metals, (iron) and organics, creating a flock that a standard sand type swimming pool filter can remove. You can then "polish" the water by going through bag type filters that go down to 0.5 microns. Bacteria size.
I've done a lot of water filtering. PM me and maybe I can help you on that. Suppliers etc.
Or, you could donate a tank to growing aquatic plants that will absorb the heavy metals and become toxic themselves. You have to "mow the lawn" and remove them as they grow or they will die, break down and release all that they absorbed. I did this in a hatchery in the Philippines. We called the tank a BARB which stood for Big Ass River Bed. The principle being that a river purifies the water by passing it through algae and organisms that absorb the impurities. Before I did that all the shrimp died at day 4. The algae that was grown in the direct water actually became toxic
That would be a first step, then chlorinate and filter.
But oops....I forget you want to do this without power.