Water hardness / Washington
Is Washington water hard? Yes.
Yes. Washington tap water measures 126 mg/L of hardness as calcium carbonate, which is hard on the USGS scale. The figure is the average DC Water publishes in its DC Water, 2025 Drinking Water Quality Report.
Where Washington sits on the scale.
Washington's published average is 126 mg/L. On the USGS scale, that is hard.
0–60Moderate
61–120Hard
121–180Very hard
180+
What it means for curly hair
Calcium and magnesium from hard water settle on the hair. Lab work shows hair takes up a limited amount of these minerals, and damaged or bleached hair takes up more than healthy hair (Evans, Marsh and Wickett, 2011).
The evidence on breakage is mixed: two small studies found lower strength after repeated hard-water rinses (Luqman et al., 2016 and 2018), while an earlier one found no clear difference (Srinivasan et al., 2013). So hard water is a likely factor, not a proven cause.
Hard water is a plausible factor, not a proven cause of breakage. Sudden shedding, itching, flaking or scalp pain needs a dermatologist, not a chelating routine.
Change less. Learn more.
What to try
Use a chelating shampoo (look for disodium EDTA, tetrasodium EDTA or sodium phytate in the ingredients) about once a month as a starting point, and follow with conditioner.
Change one thing at a time and judge it after two or three wash days, not after one.
If your hair is bleached or color-treated, go slower: chelating can feel drying.
What to avoid
Do not clarify or chelate every wash: it strips more than minerals.
Do not blame the water for sudden shedding, itching, flaking or scalp pain. That is a reason to see a dermatologist.
Every number keeps its source.
78–175 mg/L; promedio 126 mg/L. Classified with the US Geological Survey bands (soft 0 to 60, moderately hard 61 to 120, hard 121 to 180, very hard above 180 mg/L). Period: 2024. Checked against the source on 2026-10-20. Rizzado did not measure this water.
The DC Water report is public: DC Water, 2025 Drinking Water Quality Report. Hardness can vary by area and season, and private wells or buildings with their own treatment can differ. If you want your exact value, ask the utility for your address.
Sources
- DC Water, 2025 Drinking Water Quality Report
- Evans, A. O., Marsh, J. M., Wickett, R. R. (2011). The uptake of water hardness metals by human hair. Journal of Cosmetic Science, 62(4), 383-391.
- Luqman, M. W. et al. (2016). Effect of topical application of hard water in weakening of hair in men. Journal of the Pakistan Medical Association, 66(9), 1132-1136.
- Luqman, M. W. et al. (2018). To evaluate and compare changes in baseline strength of hairs after treating them with deionized water and hard water. International Journal of Trichology, 10(3), 113-117.
- Srinivasan, G., Srinivas, C. R., Mathew, A. C., Duraiswami, D. (2013). Effects of hard water on hair. International Journal of Trichology.
- U.S. Geological Survey. Hardness of water.
All cities · Phoenix · Las Vegas · Henderson · San Diego · Los Angeles · Long Beach · Anaheim · Riverside · Houston · Dallas · Fort Worth · San Francisco · Sacramento · San Jose · Oakland · Fresno · Bakersfield · Dover · Tallahassee · Boise · Springfield · Indianapolis · Topeka · Baton Rouge · Augusta · Boston · Lansing · Saint Paul · Jackson · Jefferson City · Lincoln · Concord · Raleigh · Bismarck · Columbus · Nashville · Austin · Salt Lake City · Richmond · Charleston · Madison · Cheyenne · Jacksonville · Charlotte · Portland
RIZZADO
Your water is one part of the picture.
Rizzado uses your city's water hardness, when there is a primary source, to adjust your routine. If your city is not here, it treats the value as unknown.
