Water hardness in Merriam
7.9 gpg hard
Tap water in Merriam is hard: 7.9 gpg (135 mg/L · 7.6 °dH · 13.5 °fH).
Source: WaterOne 2026 Water Quality Report (2025 data) (2025) · data checked 2026-11-03
Range across supply zones: 110–157 mg/L.
Merriam is served by WaterOne, and the 135 mg/L (7.9 gpg) figure is the utility's system-wide value from its 2026 report (2025 data), not a Merriam-only measurement. Across the system, results ranged from 110 to 157 mg/L (6.4 to 9.2 gpg). We have not confirmed which WaterOne source serves Merriam. Water in this range leaves spots on glass and some scale in water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 7.9 gpg |
|---|---|
| Utility | WaterOne (Johnson County KS) |
How Merriam compares
- Tap water in Merriam is 13 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 800 of 1372 in the United States (1 = hardest); 41 % of these cities have softer water.
- In Kansas it is number 10 of 17 cities; the regional median is 8.4 gpg.
- Nearest city with clearly harder water: Kansas City, 11 km away (16.4 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 Merriam
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| 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 Merriam water hard or soft?
It is hard: 135 mg/L as CaCO₃ (7.9 gpg, 7.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Merriam 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 Merriam water?
7.9 gpg, equal to 7.6 °dH, 13.5 °fH or 135 mg/L calcium carbonate.
What dishwasher salt setting should I use in Merriam?
For 135 mg/L (7.6 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Merriam?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: WaterOne 2026 Water Quality Report (2025 data) (2025). Method: figure published by the water supplier. WaterOne 2026 Water Quality Report (2025 data) · Outdated figure? Tell us