Water Hardness
USA Water Hardness Map|US Geological Survey water hardness map. The level of mineral content in water (primarily calcium, magnesium and iron) determines the
hardness of a given water sample. Harder water contains more metals or minerals that can bind to soap molecules, forming soap scum, and reducing the froth and effectiveness of lather.
In comparison, soft water contains very little mineral content. Soft water is less able to bond with the soap, making the soap very difficult to wash off. This presents an unfortunate conundrum: too hard, and you get soap scum and lousy lather; too soft, and you can't rinse clean.
Here's a chart that was taken from Wikipedia and also the Water Quality Association in order to assess your own water. Both tables are merged as they are not exactly scaled the same way.
Classification | hardness in mg/L | hardness in mmol/L | hardness in dGH/°dH | hardness in gpg | hardness in ppm | hardness in gpg (WQA) | ppm (or mg/L) (WQA) |
---|
Soft | 0–60 | 0–0.60 | 0-3.37 | 0-3.50 | less than 60 | <1.0 | <17.0 |
Slightly Hard | 1.0-3.5 | 17.1-60 |
Moderately hard | 61–120 | 0.61–1.20 | 3.38-6.74 | 3.56-7.01 | 60-120 | 3.5-7.0 | 60-120 |
Hard | 121–180 | 1.21–1.80 | 6.75–10.11 | 7.06-10.51 | 120-180 | 7.0-10.5 | 120-180 |
Very hard | ≥ 181 | ≥ 1.81 | ≥ 10.12 | ≥ 10.57 | > 180 | >10.5 | >180 |
Detergents
Detergent manufacturers (including "body wash") have an advantage when operating in either too hard or too soft water; detergents don't form soap scum, and they bond more readily with water so they are easier to rinse. Detergent molecules can form a slippery lather, but in general, do not, by themselves, form a durable and cushioning lather. Sometimes detergent-based products include foaming agents such as
sodium laureth sulfate.
Hard water and shaving equipment
Soap scum|Buildup of soap scum and hard water scale on the heads of a Gillette Slim Adjustable and a Gillette NEW. Some soap scum has been removed for contrast. Hard water has several effects on shaving
equipment. Scale (hard, white, calcium deposits) can form on any surface where water is allowed to dry. It is noticeable on
razors and mugs but can build up on other items. Hard water creates soap scum, and this, too, can build up on any surface that comes in contact with soap or lather. Soap scum is insoluble in water (any water). Once soap scum builds up on a shaving
brush, it affects the brush's ability to hold water and generate lather.