Is tap water safe in Caldwell?

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.

How hard is the water in Caldwell, ID?

Nearby USGS observations produce an estimate of 118 ppm (6.9 grains per gallon), classified as moderately hard. This is not a tap measurement.

Do I need a water softener in ZIP code 83605?

There is no high-hardness trigger in this profile. Confirm conditions with an at-home hardness test before purchasing equipment.

City water profile

Caldwell water quality

Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for Caldwell, Idaho.

Median indexed hardness

118PPM

2 indexed ZIPs

Range 118–118 PPM

State comparison: 50 PPM below
State hardness rank: #41 of 67
Matched utilities: 1
Active health records: 0

City summary

What the indexed records say

Caldwell has 2 published ZIP profiles across Canyon County. The indexed median is 118 PPM, compared with 168 PPM across Idaho.

Among the 67 Idahocities with an indexed median, Caldwell ranks #41from highest to lowest. Across all 78 state ZIP profiles, available estimates run from 22.2to 339 PPM.

The 118–118 PPM range shows how much the available ZIP estimates vary within the city label.

Hardness distribution

How local ZIP estimates compare

Soft0 ZIPs

Moderately hard2 ZIPs

Hard0 ZIPs

Very hard0 ZIPs

2 of 2 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.

Evidence quality

Distance, dates, and confidence

Median nearest distance: 10.9 miles
Profiles with evidence: 2/2

Confidence labels

High: 0Moderate: 2Low: 0

Observation window: Oct 30, 2017 to Nov 3, 2022.

ZIP directory

Water reports in Caldwell

Open a ZIP for site-level provenance and measurements.

ZIP code

83605

Moderately Hard

118 PPM

Nearest site: 10.9 mi
Confidence: Moderate

View full ZIP evidence →

ZIP code

83607

Moderately Hard

118 PPM

Nearest site: 10.5 mi
Confidence: Moderate

View full ZIP evidence →

Public water systems

Utilities associated with this city

Caldwell City Of

PWSID ID3140013

Groundwater

System population served: 74,000
Last reported: Jun 26, 2026

A municipal system, in-state city, and served county all agree with this Census ZCTA.

Compliance history

What EPA records show

No active health-based violation appears among the associated systems in the represented EPA reporting quarter. This does not mean every contaminant was tested at every tap.

Record	System	Period	Status
Lead and Copper Rule	ID3140013	Sep 29, 2018	Unaddressed

Practical next steps

Move from index to evidence

1. Open your ZIP. Check distance, dates, confidence, and the associated utility.
2. Read the current CCR. Confirm source water, detections, limits, ranges, and notices.
3. Test the tap when needed. Confirm health concerns or treatment sizing with the right method.

Continue comparing

Other Idaho communities

Middleton

Canyon County

118 PPM median

Nampa

Canyon County

118 PPM median

Parma

Canyon County

118 PPM median

Wilder

Canyon County

118 PPM median

Eagle

Ada County

118 PPM median

Emmett

Gem County

118 PPM median

Search all 67 Idaho cities →

Questions people ask

About water in Caldwell

Is the water hard?

The indexed city median is 118 PPM. Open the ZIP report to verify the distance and confidence behind that estimate.

Is the tap water safe?

Compliance history is utility-wide and cannot guarantee conditions at every tap. Check current notices and test when address-specific evidence is needed.

Do I need treatment?

Choose treatment only after confirming the problem at the property. A softener targets hardness; contaminant treatment requires a matching, verified performance claim.