Boston
Boston, United States has an estimated water hardness of 13 ppm (mg/L as calcium carbonate), which is classed as soft. Low scale risk. Use the lower end of detergent guidance.
Boston water hardness in every unit
| Unit | Reference estimate |
|---|---|
| mg/L or ppm (CaCO₃) | 13 |
| mmol/L | 0.13 |
| German degrees (°dH) | 0.73 |
| French degrees (°fH) | 1.3 |
| Clark degrees (°e) | 0.91 |
| Grains per US gallon (gpg) | 0.76 |
How the Boston figure was derived
- Period covered: 2025-01-01 – 2025-12-31
- Calculation: The source publishes a single typical figure and no range.
Where Boston's water comes from
- Supplier: Massachusetts Water Resources Authority (MWRA) supplies Boston’s wholesale water
- Source: MWRA’s Metro Boston system, alongside its separate Chicopee Valley Aqueduct (CVA) system serving western communities
- Official website: Massachusetts Water Resources Authority
MWRA’s 2025 data show an average hardness of 13.1 mg/L for Metro Boston and 7.6 mg/L for the CVA system, and MWRA describes its water as soft. MWRA: Water and Health (checked 2026-10-31).
How Boston compares
With a reference estimate of 13 ppm, Boston ranks 67th hardest of the 69 cities in our directory, 61 ppm below the directory median of 74 ppm. Among the cities in our directory in North America, San Antonio is the hardest at 299 ppm and Portland is the softest at 9 ppm.
What soft water means at home
Soft water rarely leaves visible scale. Kettles, taps and shower screens stay clearer for longer, and detergents lather easily, so the main risk is overdosing. Start at the minimum amount on the pack and increase only if results are poor.
Using a 13 ppm reading with your appliances
- Dishwasher: salt check manual; match the converted reading to your model. Use salt only as specified for the built-in softener.
- Coffee machine: descale when the manual or machine indicates; filter: use only a compatible filter specified by the manufacturer.
- Laundry: use the soft-water dose. Start at the label minimum and adjust for soil level.
- Kettle: Inspect for scale; follow the manual.
- Humidifier: For ultrasonic or impeller units, use low-mineral water such as distilled water. Empty and dry portable tanks daily; clean every third day. Follow manufacturer instructions.
Official manufacturer guidance
Use these references with your exact appliance model. They explain settings and maintenance, not the local water measurement. Source languages and model limits are shown; these are not affiliate links.
- Bosch US — Dishwasher salt and the low-salt indicator (en-US)
Salt and scale guidance for dishwashers equipped with a salt reservoir; it does not mean every US dishwasher uses salt.
- Bosch US — How to clean and descale Bosch dishwashers (en-US)
Cleaning and descaling procedures for Bosch dishwashers, with care-product instructions.
(checked 2026-10-20).
Hardness alone does not determine maintenance frequency. How to match your reading to an appliance manual. Dishwasher settings by brand: find your setting. Thinking about a softener? Pros and cons and sizing. Kettles and coffee machines: descaling guide. Portable humidifier care: US EPA guidance.
Frequently asked questions
Do I need dishwasher salt in Boston?
Check manual. Use salt only as specified for the built-in softener. Always follow your dishwasher manual.
How often should I descale a coffee machine in Boston?
Descale when the manual or machine indicates. Hardness alone does not determine an interval: usage and appliance design also matter. Water filter: use only a compatible filter specified by the manufacturer.
Do I need a water softener in Boston?
Almost certainly not. Soft water does not usually justify a softener.
Is hard water in Boston safe to drink?
Water hardness is mainly an aesthetic and scale issue. The World Health Organization does not set a health-based guideline value for it. Hardness affects taste, scale and detergent use rather than drinking safety, and your utility is responsible for meeting drinking-water standards. If you have a specific health or dietary concern, ask your doctor.
How to check your own water
City averages are a starting point. To get your actual figure, check the linked source (MWRA: Water and Health, 2025 data) and obtain a current report for your address from your water supplier, or dip a hardness test strip in a glass of cold tap water and read it against the chart. Strips usually report in °dH, gpg or ppm; enter the number into the Waterdial checker to convert it and see the matching appliance settings. Use a recent, correctly performed hardness test when a city estimate is too broad.
Source
MWRA: Water and Health, 2025 data, checked 2026-10-31. Guidance is general; your appliance manual takes priority.
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