Water hardness in Meridian
9.4 gpg hard
Tap water in Meridian is hard: 9.4 gpg (161 mg/L · 9 °dH · 16.1 °fH).
Source: City of Meridian, Idaho — 2025 Water Quality Report, Water Quality by Zone (2025) · data checked 2026-10-22
Range across supply zones: 119–180 mg/L.
5 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Zone 1 (City of Meridian water quality zone) | 10.5 | 180 | very hard |
| Zone 2 (City of Meridian water quality zone) | 8.9 | 152 | hard |
| Zone 3 (City of Meridian water quality zone) | 9.4 | 161 | hard |
| Zone 4 (City of Meridian water quality zone) | 7 | 119 | moderately hard |
| Zone 5 (City of Meridian water quality zone) | 10.1 | 174 | hard |
Meridian gets all of its drinking water from wells in the Treasure Valley aquifer; the Boise River surface water is used mainly for irrigation. Groundwater here dissolves calcium and magnesium from valley sediments, giving 160.8 mg/L CaCO₃ across 5 well zones (119.2–180 mg/L). Hard water, with scale on fixtures and water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 9.4 gpg |
|---|---|
| Calcium (mg/L) | 59 |
| Magnesium (mg/L) | 6.37 |
| Utility | City of Meridian Water Division |
How Meridian compares
- Tap water in Meridian is close to the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 662 of 1372 in the United States (1 = hardest); 52 % of these cities have softer water.
- In Idaho it is number 5 of 9 cities; the regional median is 9.4 gpg.
- Nearest city with clearly softer water: Star, 13 km away (5.4 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Meridian
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| LG | H2 |
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 Meridian water hard or soft?
It is hard: 161 mg/L as CaCO₃ (9.4 gpg, 9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Meridian 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 Meridian water?
9.4 gpg, equal to 9 °dH, 16.1 °fH or 161 mg/L calcium carbonate.
What dishwasher salt setting should I use in Meridian?
For 161 mg/L (9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Meridian?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: City of Meridian, Idaho — 2025 Water Quality Report, Water Quality by Zone (2025). Method: figure published by the water supplier. City of Meridian, Idaho — 2025 Water Quality Report, Water Quality by Zone · Outdated figure? Tell us