Where does the water in 51010 come from?

Water for zip code 51010 in Castana, Iowa is provided by 1 water system. Contact your local utility for specific source information, or check our detailed page for your area.

Water Hardness in 51010

Castana, Iowa · Monona County

470 PPM

27.5 GPG

Very Hard

0Soft60120180300+

High Confidence — USGS Monitoring

Dataset updated March 9, 2026Matched to 1 water systemTap readings can vary by utility zone, treatment, and plumbing. Methodology

Source context

How this ZIP reading is built

This ZIP reading is built from 1 matched water system. When more than one system is matched, the displayed value is weighted toward larger known service populations when that data is available.

Source basis

1 USGS-backed source

1 matched system total for this ZIP; USGS monitoring is used where treated-water reports are unavailable.

Water source profile

Primarily groundwater

Groundwater commonly picks up calcium and magnesium after contact with rock and soil. This profile is weighted by known population served across matched systems.

Data recency

March 9, 2026

Dataset rebuilt March 9, 2026; individual utility reporting years can vary.

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 51010

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.

1 water system

PWSID is the public water system identifier. Data Source shows whether the hardness value comes from a treated-water report, USGS monitoring, or a local estimate; source year is shown when available.

Water System	Source	Hardness	Pop. Served	Data Source
Castana Municipal Water Supply IA6715083	groundwater	470 PPM Very Hard	103	High Confidence — USGS Monitoring

Castana Municipal Water Supply

IA6715083

Very Hard

470 PPMgroundwater103 servedHigh Confidence — USGS Monitoring

Nearby Zip Codes

51051200 51040470 51034425 51056200 51572690 51558470 51026200 51063445 51060690 51523470 51044200 51019201

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

Salt-Based Water Softener

Our PickAFWFilters Fleck 5600SXT 48K Also GreatWhirlpool WHES40E 40K Also GreatAFWFilters 64K Grain Also GreatAFWFilters Iron Pro 2 64K Also GreatSpringWell Filter + Softener Combo

Water Hardness Test Kit

Our PickVarify (150 Strips)Also GreatJNW Direct (150 Strips)

Whole-House Water Filter

Our PickiSpring WGB32B 3-Stage

Water Softener Salt

Our PickMorton Clean & Protect Also GreatDiamond Crystal Bright & Soft

Shower Head Filter

Our PickWeddell Duo Also GreatAquaBliss SF100 Also GreatSprite Pure 7-Setting Also GreatAqua Earth 20-Stage

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 Castana, IA (51010).

Submit Your Data

Frequently Asked Questions

Is the water hard in Castana, IA (51010)?

The average water hardness in 51010 is 470 PPM (27.5 GPG), which is classified as very hard.

Do I need a water softener in 51010?

With hardness of 470 PPM, a water softener is recommended for homes in 51010.

Is hard water in 51010 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 51010?

Zip code 51010 in Castana, Iowa is served by 1 water system.