New York, NY water hardness

Name: New York, NY water hardness as published by New York City Department of Environmental Protection (NYC DEP)
Creator: New York City Department of Environmental Protection (NYC DEP)
License: https://www.usa.gov/government-works

New York City Department of Environmental Protection (NYC DEP) publishes an average hardness of 32 mg/L (2 grains per gallon, also its own figure) for its system, in its New York City Drinking Water Supply and Quality Report 2025. On the USGS scale that is soft water.

New York City Department of Environmental Protection (NYC DEP) published an average of 32 mg/L, with a published range of 18 to 100 mg/L shown as the bar. The plotted point is the published average. Classification bands from the USGS Water Science School.

The published figure, exactly as it appears

This is the hardness line transcribed from the source, with nothing added:

Hardness (mg/L CaCO3) — # SAMPLES 313, RANGE 18 - 100, AVERAGE 32, MCL VIOLATION No, LIKELY SOURCES Erosion of natural deposits | Hardness (grains/gallon[US]CaCO3) — # SAMPLES 313, RANGE 1 - 6, AVERAGE 2
New York City Department of Environmental Protection (NYC DEP), New York City Drinking Water Supply and Quality Report 2025

Units as published: mg/L CaCO3, with grains/gallon (US) CaCO3 given in a second row. What kind of figure it is: an average with a range. Retrieved 2026-10-16.

New York hardness in mg/L and grains per gallon

Water-quality reports use mg/L (identical to ppm). Softener instructions and plumbing specifications use grains per gallon. Both are below. Where a figure is our arithmetic rather than the utility's own number, it says so.

Figure	mg/L (ppm)	Grains per gallon	Whose number
Published average	32	2	both published by the utility
Low end of published range	18	1	mg/L published, gpg is our conversion
High end of published range	100	6	mg/L published, gpg is our conversion
Plotted on the scale above	32	1.9	published average; the gpg here is our conversion at 17.1, so it can differ slightly from a utility’s own rounded gpg figure

The conversion, both ways: gpg = mg/L ÷ 17.1 and mg/L = gpg × 17.1. Worked for this system: 32 ÷ 17.1 = 1.9 gpg. The converter does °dH and °f as well, and why the factor is 17.1 explains where the number comes from.

What this figure does not tell you

Service area and source water

Utility	New York City Department of Environmental Protection (NYC DEP)
Service area as published	The report states that the Catskill/Delaware and Croton supplies were the only sources of water in 2025. Which supply reaches a given address varies, and the Croton supply is the harder of the two, which is part of why the published range is wide.
Source water	The Catskill/Delaware and Croton supplies.
Samples behind the figure	313

Provenance of every number on this page

Source document	New York City Drinking Water Supply and Quality Report 2025
Source URL	https://www.nyc.gov/assets/dep/downloads/pdf/water/drinking-water/drinking-water-supply-quality-report/2025-drinking-water-supply-quality-report.pdf
Published by	New York City Department of Environmental Protection
Report year	2025
Year note	Hardness appears in the 2025 'Detected Conventional Physical and Chemical Parameters' table, from 313 samples. The report states the data illustrate that in 2025 New York City's drinking water continued to be of excellent quality.
Retrieved	2026-10-16
Classification bands	USGS Water Science School, retrieved 2026-10-16

Notes the report forces on this page

The report's own footnote to the grains row reads: 'Hardness of up to 3 grains per gallon is considered soft water; between 3 and 9 is moderately hard water.' That is DEP's wording and it does not match the USGS mg/L classification used for the scale on this site; where the two differ, this site shows the USGS class and says so.

If you are sizing a softener for New York water

At 2 gpg, the sizing arithmetic starts from your household's water use, not from the hardness alone. The calculator below is pre-filled with this system's figure and every other input is an editable assumption.

Whether a softener is worth installing at this hardness is a judgement, not arithmetic, and it is not one this site makes for you. Nothing here has been tested by the author.

Where New York sits against other verified systems

Soft Soft 0–60

Moderately hard Moderate 61–120

Hard Hard 121–180

Very hard Very hard 181+

Portland, OR 9 mg/L 0.5 gpg Soft
Boston, MA 16 mg/L 1 gpg Soft
Manchester, NH 17.9 mg/L 1 gpg Soft
New York, NY 32 mg/L 2 gpg Soft
Austin, TX 93 mg/L 5.4 gpg Moderately hard
Denver, CO 105 mg/L 6.1 gpg Moderately hard
Phoenix, AZ 237 mg/L 13.9 gpg Very hard
Las Vegas, NV 280 mg/L 16 gpg Very hard
San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
Indianapolis, IN 317 mg/L 19 gpg Very hard

mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.

New York, NY is the highlighted row. Every other system on this chart has its own page with its own published figure and report date. Grains per gallon are the utility's own figure where it published one, and our conversion at 17.1 mg/L per grain where it did not.

Systems with similar published hardness

Manchester, NH Manchester Water Works, 17.9 mg/L (1 gpg)
Boston, MA Massachusetts Water Resources Authority (MWRA), 16 mg/L (0.9 gpg)
Portland, OR Portland Water Bureau, 9 mg/L (0.5 gpg)
Austin, TX Austin Water, 93 mg/L (5.4 gpg)

All 10 verified systems How to find hardness in your own utility's report If you are on a well instead