Monday, March 21, 2016

Hard Water and Your Hair



Do you have hard water? The best way to find out if you have municipal water is to check your annual water report, where hardness is frequently reported. Your water treatment facility may also have water quality data online. If you cannot find hardness, give them a call and ask - but not just about hardness - ask about the pH of the water also! Why? Read on.
©Science-y Hair Blog 2016
If you use well water, find your location and hardness on this map from the United States Geological Survey (or your state or country may have its own maps) or consult a "water hardness map" for your country or region. 

Calcium and magnesium ions (an ion is a mineral with an electric charge) are the most common minerals in water. It is minerals that give water its hardness. Those minerals come from aquifers - porous stones through which water flows - or are picked up in streams and rivers.

I did some digging into a 2011 article published in the Journal of Cosmetic Science1 to find this information for you - I hope you'll be able to put it to good use.©Science-y Hair Blog 2016

Soft Water: 0-15 ppm or mg/L (1 gpg) gpg = grains per gallon
Slightly Hard: 15 or 17-60 ppm (1-3.5 gpg)
Moderately Hard:  61-120 ppm (3.5-7 gpg)
Hard water: 121-180 ppm (7-10.5 gpg)
Very Hard: >180 ppm (>10.5 gpg)

Quick summary: Hard water minerals bond to hair in the same way that conditioner does. It also finds its way beneath the surface layers. The more damaged the hair (heat, highlighting, permanent color, relaxer, permanent wave, mechanical damage in very long hair), the more minerals will bond to it, but minerals bond to little-damaged hair too. Hard water minerals can create stiffness, inflexibility, brittleness and breakage, dullness and friction in hair. For low-porosity hair, hard water can exacerbate the low porosity behavior and make hair even more intolerant of conditioners and oils.

How does hard water interact with hair?
The short story is that hard water ions have a positive charge - they are cations. Elsewhere in this blog, I refer to conditioners that bond to the hair as "cationic" because they, too have a positive charge. Hair tends to have a negative charge along cuticle edges and in damaged areas. Because positive and negative charges attract - those mineral cations from hard water can bind to your hair!

Is it damaging? Possibly. Minerals that make your hair feel more stiff might reduce elasticity or at least flexibility and increase friction in your hair. Less-flexible hair is a cosmetic problem and makes hair products behave unpredictably. But friction in hair is something that can increase porosity as hairs rub against each other, breaking off cuticles and creating tangles.

Where do the mineral ions go?
They are found on the cuticles (the outside) but also in the cortex (beneath the cuticles) and in the medulla (the inner portion of hair).©Science-y Hair Blog 2016

What does "hard water build-up" feel like or look like?
That depends upon a lot of things. The pH of your water, the width of your individual hairs, the products you use in your hair, and whether or not your hair is chemically-treated (highlighted, dyed, relaxed, permanent waved). Hard water build up tends to make hair feel dry, rough, stiff or less soft (more rigid). It may cause hair to look dull and frizzy. Some hair may get a brassy or reddish discoloration or grayish. If there is a substantial amount of iron in your water, orange shades tend to appear, especially in lighter-colored hair. Some people's hair will not grow past a certain length (i.e. shoulder-length) when their water is very hard because hair may become brittle with hard water accumulation.

Limitations of this study:
This study was done with "Caucasian" hair (non-Asian, non-African) hair. We also don't know the width of the individual hairs - probably between 80 and 90 microns.©Science-y Hair Blog 2016

What was done:
The hair was divided into study groups of un-treated (virgin) hair, lightly damaged hair (bleached a little), and heavily damaged hair (bleached a lot). The bleaching was done by the researchers to control the amount of damage. It was subjected to 6 washes in clarifying shampoo with water of different hardness (soft, moderately hard, hard and very hard) and varying pH. After that, they extracted the minerals from the hair to find out how much of the minerals from the water the hair had "taken up" during those treatments.©Science-y Hair Blog 2016

Results for hardness:
  • More-damaged hair binds up the most minerals, having lost it's water-and-cation-repelling 18-methyleicosanoic acid (18-MEA) layer, revealing an ideal surface full of negative charges to bond with the positively charged mineral cations. 
  • Lightly damaged and virgin (chemically untreated) hair also takes up mineral cations from hard water, but somewhat less than more-damaged hair.
  • The harder the water, the more minerals bonded with all hair - more damaged hair still takes up more mineral cations.
So the more damaged your hair (lightened, and by extension - permanent waves, chemically relaxed), the more minerals it will pick up from hard water. But even low porosity, virgin hair will bond with hard water minerals.©Science-y Hair Blog 2016

Hardness in relation to pH and your hair:

The higher the pH of your water, the more minerals will bind to your hair from the hard water. In pH 7 water (neutral) both bleached and unbleached hair took up lesser amounts of mineral cations than in pH 8 and pH 9 water. 

As the pH of your water goes up, so does the amount of minerals that will bind to or find their way into your hair. Damaged hair still takes up more minerals - but pH makes a significant difference. My tap water is a whopping pH 9.5, so my moderately hard water probably deposits minerals on my hair like very hard water - especially the sun-damaged parts of my hair.

If you want to know your water's pH, call the municipal treatment facility. If you have well water or want to test on your own, pH test strips can be notoriously inaccurate for tap water, even though they perform well for other applications. Get good-quality test strips or a pH meter for more accurate testing.

Manage hard water build-up:
To remove mineral build-up from your hair, you need an ingredient which can pull minerals away from their bond with your hair - a chelating ingredient. For commercial products, a chelating shampoo is what you want to look for. Most will be labeled as "hard water shampoo" or hard water treatment, or as chelating or purifying shampoos.

Chelating ingredients
  • Disodium EDTA (Ethylamine Diamine Tetraacetic Acid)
  • Tetrasodium EDTA at 0.5% to 1% - you'll find Disodium and Tetrasodium EDTA around where preservatives are listed, near the end of the ingredient list. Just because a product contains EDTA doesn't mean it is a chelating product - better to choose from products made for hard water or that say "chelating" or "removes minerals" which contains EDTA.
  • Pentasoidum Pentetate - similar to EDTA
  • Sodium gluconate - a more "natural" chelating ingredient, which may be effective at concentrations similar to EDTA.
  • Sodium phytate, phytic acid (these may work, but not as well as EDTA)


Note: I've listed "Sulfate-free" products. Sulfate free does not mean the product is non-drying, read reviews online and buy samples whenever possible if you are concerned about over-drying your hair.

Examples are: 


DIY Homemade rinses: Citric acid is also a chelating ingredient, but in most shampoos or conditioners, it is used to adjust pH and may have no impact on minerals on your hair. You can make a rinse with:

Citric acid powder or crystals: 1/16 teaspoon (0.3 ml) citric acid in 1 cup (230 ml) distilled water if you know your hair is okay with acidic treatments - or 1/16th to 1/8 (0.3 to 0.6 ml) teaspoon per 1 1/2 to 2 cups (350 to 475 ml) if you're not sure.

Vinegar: 1 tablespoon (15 ml) vinegar in 1 cup (230 ml) water

Lemon juice can be mixed with distilled water, lemon juice contains citric acid. Start with 1 part lemon juice and 4 parts water and use it with heat as for the citric acid rinse. You might try mixing lemon juice with conditioner if you're a conditioner-only sort of person.

How to use homemade rinses: Leave these rinses on your clean, wet hair for a few minutes with some heat, then rinse well and condition. The pH of this is quite low, so it is best to try it on a small test-strand before applying to all your hair to make sure this works with your hair.


Diagnose hard water build-up:
If you have only slightly hard water with a pH around 7 and low porosity hair or only mildly damaged hair, you may not have issues with hard water. Try doing an entire wash with distilled water. There are no minerals in distilled water and the pH is around 6. If you find your hair shows little difference, you may not have a problem with hard water. If you notice that your hair is softer or more flexible after a distilled water wash, you may have problems with hard water.

Detergents: In really hard water, most detergents won't create foam. I say most detergents - anionic detergents in particular. The anionic (negatively charged) end of the detergent interacts with the positively charged minerals to prevent formation of foam. It also means that the combination of detergent + minerals may form "scum" on your shower - and your hair. Soap (real soap - fats reacted with a strong base like lye) is the worst offender because of the fats in the soap. But it's worth trying other shampoos to see if they alter your hair's mineral "load."
The non-ionic detergents and cationic (or amphoteric/zwitterionic) detergents are less affected by hard water. So if your shampoo contained only non-ionic surfactants like Decyl glucoside (and/or Lauryl glucoside), at least the shampoo would not be contributing to the accumulation of minerals nor be rendered less effective by them. Amphoteric/zwitterionic detergents like Cocamidopropyl Betaine, Disodium Lauroamphodiacetate, Sodium Cocoamphoacetate (a.k.a. Disodium Cocoamphodiacetate) won't interact with minerals in water either.

How often to use chelating treatments and other miscellany: 
Use a chelating treatment again when the effects of the last one have worn off. Some of the products recommend weekly use, but that may or may not be practical or necessary depending on how often you wash your hair.

Some fine-haired or thin-haired people don't mind a little bit of hard water build-up - it adds some volume and "grip" to hair.

If you use soap - real soap, (some ingredient lists try to pass soap off as sodium carboxylate, which is what it is, but doesn't let the customer know that soap scum may occur). You will accumulate hard water build up more readily due to interaction between minerals and the fats in the soap.

I have no information about chelating ingredients in conditioners. My thoughts are mixed, though I think it may work and I hope I'll bear from blog readers about their experiences with EDTA in conditioners - chelating conditioners. Or mixing lemon juice with conditioner.


Most filters you can put on your shower will NOT soften water, even if they try to indicate that they do. You cannot soften water without a resin chamber which needs regular recharge with salt. The only shower-based water softener I know of is "Showersticks" brand.

1A.O. Evans, J.M. March, R.R. Wickett, 2011. The Uptake of Water Hardness Metals By Human Hair. Journal of Cosmetics Science 62, p. 383-391