Water hardness in Janesville
20.4 gpg very hard
Tap water in Janesville is very hard: 20.4 gpg (350 mg/L · 19.6 °dH · 35 °fH).
Source: Wisconsin DNR Drinking Water System portal (Janesville Water Utility) (2026) · data checked 2026-10-20
Range across supply zones: 340–370 mg/L.
Janesville Water Utility pumps groundwater from deep wells in southern Wisconsin's sandstone and dolomite aquifers. These aquifers dissolve calcium and magnesium, giving very hard water at 350 mg/L CaCO₃ (340–370 mg/L). Heavy scale on heaters and fixtures; softeners are common.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 20.4 gpg |
|---|---|
| Utility | Janesville Water Utility |
How Janesville compares
- Tap water in Janesville is 126 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 129 of 1372 in the United States (1 = hardest); 90 % of these cities have softer water.
- In Wisconsin it is number 73 of 448 cities; the regional median is 14.3 gpg.
- Nearest city with clearly softer water: Footville, 16 km away (15.8 gpg).
- Nearest city with clearly harder water: Monona, 49 km away (26.9 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Janesville
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 20 °dH |
| AEG / Electrolux | 5 |
| Beko | 5th |
| Hoover | S3 |
| LG | H3 |
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 Janesville water hard or soft?
It is very hard: 350 mg/L as CaCO₃ (20.4 gpg, 19.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Janesville safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Janesville water?
20.4 gpg, equal to 19.6 °dH, 35 °fH or 350 mg/L calcium carbonate.
What dishwasher salt setting should I use in Janesville?
For 350 mg/L (19.6 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Janesville?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Wisconsin DNR Drinking Water System portal (Janesville Water Utility) (2026). Method: figure published by the water supplier. Wisconsin DNR Drinking Water System portal (Janesville Water Utility) · Outdated figure? Tell us