Quick Answer: Des Moines water is very hard, ranging from 10 to 14 grains per gallon (gpg), sourced from the Des Moines River and Raccoon River. Iowa's intensive agricultural activity makes nitrate contamination a major concern — Des Moines Water Works famously sued upstream drainage districts over nitrate levels. A water softener is essential, and a reverse osmosis system is strongly recommended for drinking water to address nitrates and agricultural chemicals.
Is Des Moines Water Hard or Soft?
Des Moines Water Hardness Data
According to Des Moines Water Works annual water quality reports, Des Moines water hardness ranges from 10 to 14 grains per gallon (gpg) — classified as very hard. The city uses chlorine as its primary disinfectant, which is easily removed by standard activated carbon filters. See the home water hardness test guide to verify your specific tap's hardness level.
Where Does Des Moines Get Its Water?
Des Moines draws its drinking water from Des Moines River and Raccoon River, managed by Des Moines Water Works.
Des Moines Water Works draws water from two Iowa rivers: the Raccoon River (primary source) and the Des Moines River (supplemental). Both rivers drain Iowa's intensively farmed agricultural landscape, making them among the most nitrate-contaminated water sources in the US. The utility processes water at the Fleur Drive Water Treatment Plant, which includes advanced treatment such as biological denitrification and ion exchange to manage nitrate levels. The hardness comes from calcium and magnesium dissolved from Iowa's limestone bedrock.
What Contaminants Are in Des Moines Water?
According to Des Moines Water Works annual water quality reports and independent EWG Tap Water Database analysis, the primary concerns in Des Moines drinking water include:
- Disinfection Byproducts: Des Moines uses chlorine to disinfect water. When chlorine reacts with natural organic matter, it forms trihalomethanes (TTHMs) and haloacetic acids (HAA5) — compounds linked to increased cancer risk with long-term exposure.
- Key Concerns: Nitrates from agricultural runoff (Des Moines Water Works sued upstream counties over nitrate levels), hard water scale, disinfection byproducts, and atrazine pesticide.
- Agricultural and Urban Runoff: Depending on watershed proximity to farmland or industry, nitrates, pesticides, and industrial chemicals may be present at low levels.
Hard Water Effects in Des Moines
At 10–14 gpg, Des Moines water causes significant scale buildup in water heaters, pipes, dishwashers, and faucets. Limescale accumulation reduces water heater efficiency by up to 48% over time and shortens appliance lifespan considerably.
The EPA estimates hard water costs US households $800–$1,500 per year in excess energy, detergent use, and appliance wear. For Des Moines residents with very hard water, investing in a quality water softener typically pays for itself within 2–4 years.
Best Water Treatment Solutions for Des Moines Homes
1. Water Softener — Yes
Yes — at 10–14 gpg, Des Moines has very hard water; a whole-home water softener is strongly recommended. A traditional salt-based ion-exchange water softener is the most effective solution for Des Moines's very hard water. Look for a softener sized for your household (grain capacity based on water hardness × daily usage). See our top water softener picks for 2026.
2. Whole-Home Carbon Filtration
A whole-home carbon filter removes chlorine, disinfection byproducts (TTHMs, HAA5), chlorine taste and odor, and many industrial chemicals before water enters your home's plumbing. A standard activated carbon block filter works well for chlorine removal in Des Moines.
3. Reverse Osmosis System (Drinking Water)
For drinking and cooking water, a reverse osmosis (RO) system under the kitchen sink is the most comprehensive solution. RO removes dissolved minerals to near-zero levels, plus filters out PFAS, nitrates, heavy metals, radium, disinfection byproducts, and most other contaminants of concern in Des Moines water. Look for NSF/ANSI 58-certified systems. See our guide on water treatment options for 2026.
Des Moines Water Hardness vs. Other Major Cities
| City | Hardness (gpg) | Classification |
|---|---|---|
| Las Vegas, NV | 16–18 | Extremely Hard |
| Phoenix, AZ | ~16 | Extremely Hard |
| Dallas, TX | ~14 | Very Hard |
| Des Moines, IA | 10–14 | Very Hard |
| Chicago, IL | ~8.2 | Hard |
| Ottawa, ON | 2.5–5 | Soft to Moderately Soft |
| Seattle, WA | ~1.2 | Soft |
How to Test Your Water Hardness at Home
You can verify Des Moines's water hardness at your specific tap using these simple methods:
- Test strips: Dip a water hardness test strip in a glass of cold tap water. Results appear in seconds. Accuracy: ±1–2 gpg. Inexpensive and widely available.
- The soap test: Fill a clear bottle halfway with tap water, add 10 drops of pure liquid castile soap, and shake vigorously. Abundant, persistent suds = soft water. Milky, soapy film with few suds = hard water.
- Visual check: White crusty deposits inside your toilet tank, on showerheads, or around faucet bases are limescale — a reliable sign of hard water above ~7 gpg.
- Lab test: For precise results, send a water sample to a certified lab. This also tests for contaminants beyond hardness. See our full home water testing guide.