What is hard water?
We call water “hard” if it contains a lot of dissolved calcium or magnesium in it. Hard water causes two problems:

It can cause “scale” to form on the inside of pipes, water heaters, showers and so on. The calcium and magnesium ions precipitate out of the water and stick to surfaces. The scale doesn’t conduct heat well and it also reduces the flow through pipes. Eventually, pipes can become completely clogged. Also it reacts with soap to form a sticky scum, and reduces the soap’s ability to lather.

As natural water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals. The degree of hardness becomes greater as the calcium and magnesium content increases.

  • < 1 grain per gallon (GPG) is soft.
  • 1 to 3.5 GPG is slightly hard (water softener generally not required)
  • 3.5 to 7 GPG is moderately hard (would see improvement with water softener)
  • 7 to 10.5 GPG is hard (big improvement, financial payback with water softener)
  • Over 10.5 GPG is very hard (huge improvement, quick payback with water softener)

(1 GPG = 17.1 PPM or Mg/L).

Related Links:
Why should you consider installing a whole house water softener
What are the real differences between salt softened water and water from The whole house water conditioner?
Water Softener – What it is and where you use it?
4 Reasons To Consider Whole House Water Filters
Shower Water Filter Softener Removes Chlorine & Flouride