Why can the existing treatment plants be modified to take out the chloride?
They can be modified, but the treatment needed (microfiltration and reverse osmosis) is very costly. The cost to construct additional facilities to remove the chloride load from existing residential automatic water softeners is estimated at $74 million. By contrast, the cost of providing a rebate program paying residents for their AWS (plus free removal and disposal) is estimated at $2.5 million.
