Water hardness in Nagareyama
67 mg/L moderately hard
Tap water in Nagareyama is moderately hard: 67 mg/L (3.9 gpg · 3.8 °dH · 6.7 °fH).
Source: Nagareyama City Waterworks and Sewerage Bureau, water quality test results FY2025 (令和7年度水質検査結果) (2025) · data checked 2026-11-05
Range across supply zones: 53–81 mg/L.
The figures come from the city waterworks bureau's FY2025 results for its four treatment plants (Otakanomori, Tobu, Edogawadai, Nishihirai). Plant averages run from 58 to 70 mg/L, so the 67 mg/L shown is the median of four plant outlets, with a range of 53 to 81 mg/L over the year. These are plant outlets, not household taps, and the published results do not say which neighbourhood is served by which plant. Expect moderate scale in kettles, and check the bureau's current results if you want a tighter number.
Japanese waterworks report hardness (硬度) in mg/L CaCO₃; the standard is 300 mg/L and the target 10–100 mg/L.
Water data
| Total hardness | 67 mg/L |
|---|---|
| Utility | 流山市上下水道局 Nagareyama City Waterworks and Sewerage Bureau |
How Nagareyama compares
- Tap water in Nagareyama is 33 % harder than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 42 of 228 in Japan (1 = hardest); 82 % of these cities have softer water.
- In Chiba it is number 10 of 11 cities; the regional median is 76 mg/L.
- Nearest city with clearly softer water: Higashiyamato, 44 km away (48 mg/L).
- Nearest city with clearly harder water: Ichihara, 41 km away (86 mg/L).
Ranking of the hardest and softest water in Japan →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Nagareyama
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 4 °dH |
| AEG / Electrolux | 2 |
| Beko | 1st |
| Hoover | S1 |
| LG | H1 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Nagareyama water hard or soft?
It is moderately hard: 67 mg/L as CaCO₃ (3.9 gpg, 3.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Nagareyama safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Japanese waterworks report hardness (硬度) in mg/L CaCO₃; the standard is 300 mg/L and the target 10–100 mg/L.
How many grains per gallon is Nagareyama water?
3.9 gpg, equal to 3.8 °dH, 6.7 °fH or 67 mg/L calcium carbonate.
What dishwasher salt setting should I use in Nagareyama?
For 67 mg/L (3.8 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Nagareyama?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Nagareyama City Waterworks and Sewerage Bureau, water quality test results FY2025 (令和7年度水質検査結果) (2025). Method: figure published by the water supplier. Nagareyama City Waterworks and Sewerage Bureau, water quality test results FY2025 (令和7年度水質検査結果) · Outdated figure? Tell us