Water Hardness Levels


Hardness is a measure of the amount of certain naturally occurring minerals found in water, namely calcium and magnesium. While calcium and magnesium are essential minerals for human health, hardness may cause spotting on dishes and shower walls, affect the lathering of soap (more hardness = less lathering or suds = more soap/detergent required to do the same job) or cause deposits on water related fixtures. The following table shows the average hardness levels for representative sites throughout the district. The District has implemented measures to reduce hardness levels, which in the past have been significantly higher than those shown below. Depending on the exact blend of water coming from different sources at any given moment, your water hardness levels may vary from those shown on the chart. These values are for general reference only.

NOTE: The hardness values given in the table below are expressed in parts per million (ppm) as calcium carbonate (CaCO3). Many water softeners use grain per gallon (gpg) values for determining settings – please refer to your manual to see how settings are calculated. To convert ppm to grains per gallon, simply divide the ppm values shown on the chart by 17.1.

Hilton Head PSD Water Hardness Guide

The following table provides a general guideline for determining the hardness of water. This table can be consulted when choosing your water softener settings. Always consult your water softener manufacturer’s recommended settings:

  • 1 to 3.5 grains per gallon (gpg); or 17 to 60 parts per million (ppm) = Slightly Hard
  • 3.5 to 7 gpg; or 60 to 120 ppm = Moderately Hard
  • 7 to 10 gpg; or 120 to 180 ppm = Hard
  • More than 10.5 gpg or 180 ppm = Very Hard




      ppm CaCO3        

May 2013


      ppm CaCO3        

July 2014

Bayley Point Lane at Ladson Court

86 76

Beach City Road (near Dillon/Fish Haul)

38 52

End of Brams Point Road

128 132

Cardinal Road at Hunter Road

72 136

Cherry Hill Lane at Tucker Ridge Court

24 90

Coggins Point Road (near Sherman/Doubloon)

18 100

Colonial Drive

36 154

Crooked Pond Drive at Anglers Pond Lane

126 20
Dolphin Head Drive at Dolphin Head Lane 52 44

Dolphin Head Drive at Whitetail Deer Lane

92 44

End of Ft. Howell Drive

112 24

Ft. Howell Drive at  Lennox Avenue

28 100

Ft. Walker Drive at  Oak Creek Drive

16 172

Flying King Court at Seabrook Drive

52 48

Ghost Crab Way at Folly Field Road

14 16

Harbour Passage at Millwright Drive

180 188

Headlands Drive at Misty Morning Drive

196 260

Hickory Forest Drive at Hickory Nut

80 28

High Bluff Road at Wing Shell Lane

72 28


88 18

Wm. Hilton Parkway at Singleton Beach

16 14

Main Street at Main Street Bowling Lanes

56 76

Mariners Cove

176 186

Marshland Road at Leg-O-Mutton

30 108

Marshland Road at River Club Drive

128 132
Old Fort Drive at Old Fort Lane 60 92

Oyster Reef Drive at Whooping Crane Way

56 48

Spanish Wells Road at Owens Drive

172 216

Spanish Wells Road at Tansyleaf Drive

44 138

Wedgefield Drive at Sheldon Lane

108 110

Widewater Road at McIntosh Road

128 128
Wildhorse Road at Gumtree Road 28 244

Beaufort-Jasper Supply Water

40 40