Utilities / District of Columbia

District of Columbia water hardness

1 District of Columbia system with a hardness figure read from an official page, each on the retrieval date printed against it below. This is not a list of every utility in District of Columbia; it is the list of those whose published figure has been verified here.

Soft Soft 0–60

Moderately hard Moderate 61–120

Hard Hard 121–180

Very hard Very hard 181+

Washington, DC 95 mg/L 5.6 gpg Moderately hard

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

District of Columbia systems on the USGS classification. Each row links to that system's published figure, report year and conversion. 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.

Washington, DC — DC Water 95 mg/L (5.6 gpg) Moderately hard Published range 70–120 mg/L. DC Water, “How hard is the water in the District of Columbia?”. Retrieved 2026-10-17.

If your District of Columbia system is not above

Only 1 District of Columbia system has been transcribed here, so most District of Columbia readers will not find theirs. Find the water system that serves you walks through the free EPA search that names your system and the EPA lookup that finds its annual report, which is the document that carries a hardness figure for your water. There is no ZIP-code hardness figure on this site, and that page explains why a ZIP code cannot carry one honestly: a ZIP code is a postal boundary and a water system is a pipe network, and they do not line up.

Other states with verified systems

All verified systems Convert a figure from your own report How to read a water quality report