I live in Khon Kaen Province and there is something in the well water. Others have told me they have it, but my in-laws who live in town Khon Kaen dont.

Its some kind of mineral I quess. It cant be seen looking at the water, but it builds up on tile and plastic. Its white and becomes brittle. My guess is its limestone or something like that. I have to clean it from the shower head every couple months or it becomes completly blocked. Our toilet wasnt flushing solids, so I removed it, broke it apart and this stuff had reduced the outlet hole about 50%!

Any ideas how to deal with it?

I'm in Loei province and we also have that problem. A water softener will remove the minerals but softeners are few and far between in Thailand. Salt for regeneration is not easily available and even if it were, where are you going to dump the salt water? There are reverse osmosis systems available but they are expensive and costly to run for a big enough unit to supply your total water needs. We save all the rain water we can and use it to wash clothes and shower. Village well water is used for everything else. Before the next rainy season I will add more storage capacity.