While there are many effects of soft water on hair, two of the most noticeable pertain to cleanliness and overall texture and feel. “Soft” water is water that is generally low in calcium, and this characteristic often leads to increased lather and better bubbles from shampoo and other cleansing products. Hair often gets a lot cleaner as a result, since the shampoo is able to more deeply penetrate each strand. Deep cleaning can strip some of the hair’s essential oils away, though, which can lead to locks that look listless, flat, or dull. Many people also find that their hair lacks body or volume under these circumstances. Styling products and tools can often overcome these effects, but getting the right coif often takes a bit of time and experimentation.
Understanding Water Softness
Whether water is classified as soft or hard mainly depends on its measured calcium content. Basically, the higher the calcium content, the harder the water. Soft water tends to be found in places with low levels of limestone deposits or in residences where water softeners or filters are installed. In addition to hair, the chemical composition of water can also impact things like dishwashing, appliance maintenance, and erosion. It’s usually somewhat difficult to taste a difference in drinking water, but both are usually safe to consume. The biggest contrasts come with respect to how they interact with different substances and whether they leave a residue.
Calcium content is typically measured in parts per million. To be considered soft water, less than 160 parts per million of calcium must be present. For slightly hard water, the acceptable range is 160 to 320 parts per million, and anything over 460 parts per million is considered very hard. In addition to calcium, other minerals such as magnesium and manganese are also present in hard water, although in minimal amounts. The calcium content in water naturally rises wherever significant amounts of limestone are found in the ground.
Impact on Shampoo
One of the biggest and usually also one of the most noticeable effects of soft water on hair has to do with how well shampoos perform, and how clean the hair actually gets as a result. People who lather their hair with soft water often see more bubbles than they would in more calcium-rich water, in part because the calcium ions tend to bind to the shampoo as well as the hair, reducing the foam that ultimately results. Bathers using soft water typically don’t have to use much cleanser, since a little really will go a long way.
Natural soaps, such as Castile soap, tend to leave a residue behind after washing that makes the hair look stringy and greasy when washed in hard water. Under these circumstances, using soft water on hair proves superior, as all residue is easily rinsed away. As people migrated to increasingly urban areas and in many cases lost ready access to soft water, manufacturers began coming up with alternative cleaning agents, such as sodium lauryl sulfate, to make their products react well under hard water conditions. Otherwise, the only options available would be to purchase water softeners or shower filters to soften the hard water so it would clean more effectively.
Shine and Body
Despite having better cleaning properties, using soft water for hair washing has its drawbacks. Putting the effects of cleaning agents aside, using soft water tends to make hair appear flat and lifeless. While using soft water on hair is helpful in washing away unwanted residue and buildup, factors such as shine and body tend to be sacrificed.
There’s also some controversy when it comes to how clean hair really needs to be, or even how clean it should be. Soft water often leads to hair that is literally “squeaky clean,” since the chemical composition of the water usually strips out almost all oils and residues. This can cause the strands to make a slight squeaking or high-pitched sound when they’re rubbed against each other. While this can be good when it comes to removing the effects of styling products, it can be bad where natural oils are concerned. Most experts agree that some natural build-up is healthy, and can actually prevent strands from damage.
Solutions and Work-Arounds
People using soft water often end up using volumizing styling products to give their hair additional body and bounce. Heated tools like blow driers, curling irons, and straighteners can also be helpful, and certain gels and creams can restore lost shine. Whether people prefer using soft or hard water usually depends on personal preferences and what they're used to, and there are pros and cons each way.