Water Hardness in 50138
Knoxville, Iowa · Marion County
Dataset updated March 9, 2026Matched to 7 water systemsTap readings can vary by utility zone, treatment, and plumbing. Methodology
How this ZIP reading is built
This ZIP reading is built from 7 matched water systems. When more than one system is matched, the displayed value is weighted toward larger known service populations when that data is available.
Hardness is a mineral-content reading, not a drinking-water safety rating. Use it for scale, appliance, and softener decisions; check your utility report or test your tap before sizing treatment equipment. See how we calculate local readings.
Water Systems Serving 50138
These are the systems matched to this ZIP code. The displayed ZIP value is weighted toward larger known service populations when population data is available.
| Water System | Source | Hardness | Pop. Served |
|---|---|---|---|
Pella Water Works Department IA6368033 | groundwater | 350 PPM Very Hard | |
Knoxville Water Works IA6342036 | groundwater | 287 PPM Very Hard | |
Marion Co. Rural Water District IA6342711 | groundwater | 287 PPM Very Hard | |
Wheel Estates Mhc IA6342301 | groundwater | 287 PPM Very Hard | |
Hillock Estates IA7727608 | surface water | 335 PPM Very Hard |
Nearby Zip Codes
What This Means For You
Recommendations are based on the displayed ZIP hardness reading. Confirm your tap reading before sizing or buying treatment equipment.
Very Hard Water - Treatment Strongly Recommended
Your water is very hard. Without treatment, you can expect significant scale buildup in pipes and appliances, higher energy bills from reduced water heater efficiency, and persistent issues with skin and hair dryness.
Recommended Products
Learn more: Do I Need a Water Softener? | Salt-Based vs Salt-Free | Size Calculator | How to Test Your Water
Know your water hardness?
If you've tested your water or have your utility's CCR report, share your reading to help us improve accuracy for Knoxville, IA (50138).
Frequently Asked Questions
Is the water hard in Knoxville, IA (50138)?
The average water hardness in 50138 is 315 PPM (18.4 GPG), which is classified as very hard.
Do I need a water softener in 50138?
With hardness of 315 PPM, a water softener is recommended for homes in 50138.
Is hard water in 50138 safe to drink?
Water hardness itself is a mineral-content reading, not a drinking-water safety rating. Calcium and magnesium are naturally occurring minerals, but you should check your utility's Consumer Confidence Report for contaminant and compliance information.
How many water systems serve 50138?
Zip code 50138 in Knoxville, Iowa is served by 7 water systems.
Learn More About Your Water
Best Water Softeners 2026: Top Picks for Every Budget
We compared salt-based, salt-free, and portable water softeners. Here are our top picks based on water hardness level, home size, and budget.
12 min readWater Softener Size Calculator: What Grain Capacity Do You Need?
Calculate the right water softener size for your home. Enter your household size and water hardness to get a grain capacity recommendation.
7 min readHard Water and Hair: Effects, Damage Signs & What Actually Helps
How mineral buildup affects your hair - and what to do about it based on your actual water hardness level.
10 min read