They appear to be plugging with some sort of copper oxide - turquoise in color. Very fine particles but causing problems throughout the house. We have all copper plumbing, could that be the source and, if so, what to do about it? We're on well water, run through a 5 micron (nominal) filter, then through a water softener.

Most likely an oxide or other insoluble salt of Copper, flaking off the inside of the piping. Cu reacts with the other chemicals in the water and slowly precipitates out. Common with well water. The filter does nothing as the oxide is in the piping past the filter. At our mountain house in N. GA, house, I was cautioned against Copper for that exact reason and, because copper has some Zinc impurities, acidic well water causes pinholes. 13 years with CPVC, good so far.

Thanks. I can put point of use filters in some places but not the showers we use the most, at least not without opening walls.

Would these be applicable?

Shower Water Filter Reviews & Comparisons | Water Filter Comparisons (http://www.waterfiltercomparisons.com/shower-filters-reviews/?kwid=76553533563316x1224855999594624x279195071#st art_compare&d=mp&utm_source=bing&utm_medium=cpc&utm_campaign=%5BADL%5D%20%5BNonbrand%5D%20Shower%2 0-%20Unspecified%20(Broad)&utm_term=%2Bwater%20%2Bfilter%20%2Bfor%20%2Bshower&utm_content=Filters%20-%20Shower%20-%20Water)

https://www.home-water-purifiers-and-filters.com/kdf-filter.php

Or

https://www.amazon.com/s/?ie=UTF8&keywords=kdf+shower+water+filter&tag=mh0b-20&index=aps&hvadid=78546415225105&hvqmt=b&hvbmt=bb&hvdev=c&ref=pd_sl_5nnkq94vz9_b