Water is considered to be hard at {HEAD ~ a hardness level} of {TAIL ~ about 170 ppm} or greater and very hard at a hardness level of about 300 ppm or greater 
Water is considered to be hard at { HEAD ~ a hardness level } of { TAIL ~ about 170 ppm } or greater and very hard at a hardness level of about 300 ppm or greater
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH