How hard is the water in Marengo, IA?

Nearby USGS observations produce an estimate of 268 ppm (15.7 grains per gallon), classified as very hard. This is not a tap measurement.

Do I need a water softener in ZIP code 52301?

At 268 ppm, a correctly sized whole-house softener can reduce scale buildup and hard-water spotting. Treatment for hardness does not remove all health-related contaminants.

Local water dashboard

Official source aggregation

Water quality in Marengo, IA 52301

Q: Is tap water safe in Marengo?

EPA SDWIS shows no active health-based violation in this profile's reporting window. That is not the same as proving every contaminant is absent, and federal data can lag state and utility records.

A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Iowa County.

1 reported benchmark flag

Primary matched system: Marengo Water Supply
Source water: Groundwater
County: Iowa County
Profile updated: Jun 17, 2026

At a glance

What the current records say

EPA quarter 2026Q2

Hardness

Very Hard

268 PPM · 15.7 GPG

Compliance screen

No active flag

0 active health-based records

Lead 90th percentile

0.008 mg/L

53% of action level

Utility match

2 systems

Serves 2,435 people system-wide

Hardness meter

How hard is the water?

Very Hard

Estimated local hardness

USGS hardness classification scale

268 PPM

Soft
0–59Moderate
60–120Hard
121–180Very hard
181+

Parts per million

268

mg/L as CaCO₃ equivalent

Grains per gallon

15.7

1 GPG ≈ 17.1 PPM

What this means at home

At 268 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.

USGS sites used

Nearest site

2.9 mi

Observation range

Feb 9, 2016–Mar 3, 2026

Estimate confidence

Moderate

Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: 081N10W17CCB (Well).USGS source documentation ↗

Regional context

Is 52301 typical?

These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.

Marengo median

268 PPM

About the same

1 indexed ZIP readings · Range 268–268 PPM

Iowa median

281 PPM

13 PPM lower

721 indexed ZIP readings · Range 182–834 PPM

EPA benchmark screen

Contaminant snapshot

Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.

1 pass1 fail

Lead (PB90)

0.008 mg/L

Reported Dec 31, 2025

Copper (CU90)

Not available

No numerical 90th-percentile result

Numerical coverage

2 comparable results

Missing values remain blank; absence is not treated as a pass.

Lead (90th percentile)

Measured in mg/L

Pass

Local 0.008

EPA limit 0.015

Nitrate

Measured in MG/L

Fail

Local 13

EPA limit 10

Share of EPA benchmark

100% line = listed limit

EPA SDWIS compliance

Reported violation history

Open EPA source documentation ↗

2026Q2

All records: 9
Health-based: 9
Active health-based: 0

Contaminant or rule	System	Status	Period
NitrateHealth-basedReported 13 MG/L · MCL 10	IA4800634	Resolved	Oct 1, 2023through Oct 31, 2023
NitrateHealth-basedReported 13 MG/L · MCL 10	IA4800634	Resolved	Sep 1, 2023through Sep 30, 2023
NitrateHealth-basedReported 14 MG/L · MCL 10	IA4800634	Resolved	Aug 1, 2023through Aug 31, 2023
NitrateHealth-basedReported 13 MG/L · MCL 10	IA4800634	Resolved	Jul 1, 2023through Jul 31, 2023
NitrateHealth-basedReported 13 MG/L · MCL 10	IA4800634	Resolved	Jun 1, 2023through Jun 30, 2023
NitrateHealth-basedReported 12 MG/L · MCL 10	IA4800634	Resolved	May 1, 2023through May 31, 2023
NitrateHealth-basedReported 11 MG/L · MCL 10	IA4800634	Resolved	Apr 1, 2023through Apr 30, 2023
NitrateHealth-basedReported 16 MG/L · MCL 10	IA4800634	Resolved	Mar 1, 2023through Mar 31, 2023
NitrateHealth-basedReported 19 MG/L · MCL 10	IA4800634	Resolved	Apr 1, 2022through Mar 31, 2023

No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.

Solutions matcher

Your personalized water action plan

Matched to Marengo ZIP 52301 using 268 PPM nearby hardness and 2 reported measurement benchmarks.

2 matches

Scale protection

High-Capacity Whole House Water Softener

268 PPM is 2× the high-hardness trigger used by this matcher.

Designed to reduce scale on fixtures, water heaters, glassware, and plumbing throughout the home.

Compare whole-house systems

Drinking water protection

Under-Sink Reverse Osmosis System

Nitrate has a measured benchmark flag or active health-based SDWIS record in this profile.

A certified multi-stage RO system targets a broader range of dissolved contaminants at the kitchen tap.

Explore under-sink filtration

Affiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.

Frequently asked

Water questions for Marengo

Is tap water safe in Marengo?+

EPA ECHO shows no active health-based violation for the associated systems in this reporting snapshot. This does not prove every contaminant is absent; federal records can lag and household plumbing can change tap conditions.

How hard is the water?+

Nearby USGS observations produce an estimate of 268 PPM, or 15.7 grains per gallon, classified as very hard. This is not a household tap measurement.

Do I need a water softener?+

At 268 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.