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