Hardest Water in Colorado

23 cities ranked by water hardness. Parker tops the list at 210 PPM.

Colorado's water hardness varies significantly by city and water source. The state average across our database is 99 PPM, which is moderately hard. Some cities need treatment while others do not. 26% of cities we track in Colorado have hardness above 120 PPM.

Parker has the hardest water at 210 PPM (12.3 GPG). At this level, expect visible scale on faucets, reduced water heater efficiency, and higher soap usage. A salt-based water softener can pay for itself over time in energy and consumable savings, though the payback depends heavily on your hardness and whether you heat water with gas or electricity. Estimate your payback. Boulder North has the softest water at just 40 PPM. No softener is needed.

#	City	PPM	GPG	Level	Softener?
1	Parker	210	12.3	Very Hard	Yes
2	Castle Rock	200	11.7	Very Hard	Yes
3	Brighton	160	9.4	Hard	Recommended
4	Greeley	152	8.9	Hard	Recommended
5	Lafayette	150	8.8	Hard	Recommended
6	Aurora East	120	7	Hard	Recommended
7	Fort Collins	105	6.1	Moderately Hard	Optional
8	Colorado Springs	101	5.9	Moderately Hard	Optional
9	Denver	90	5.3	Moderately Hard	Optional
10	Fort Collins South	90	5.3	Moderately Hard	Optional
11	Arvada	81	4.7	Moderately Hard	Optional
12	Thornton	78	4.6	Moderately Hard	Optional
13	Boulder	77	4.5	Moderately Hard	Optional
14	Centennial	75	4.4	Moderately Hard	Optional
15	Aurora	73	4.3	Moderately Hard	Optional
16	Lakewood	73	4.3	Moderately Hard	Optional
17	Pueblo	72	4.2	Moderately Hard	Optional
18	Loveland	72	4.2	Moderately Hard	Optional
19	Broomfield	70	4.1	Moderately Hard	Optional
20	Longmont	68	4	Moderately Hard	Optional
21	Westminster	66	3.9	Moderately Hard	Optional
22	Durango	45	2.6	Slightly Hard	No
23	Boulder North	40	2.3	Slightly Hard	No

Frequently Asked Questions

What is the average water hardness in Colorado?

Across 23 cities in our database, the average water hardness in Colorado is 99 PPM (5.8 GPG). This ranges from 40 PPM in Boulder North to 210 PPM in Parker.

Do I need a water softener in Colorado?

It depends on your city. 26% of Colorado cities in our database (6 of 23) have hardness above 120 PPM where a softener provides measurable benefit. Check your specific city above.

Which Colorado city has the softest water?

Boulder North has the softest water in Colorado at 40 PPM (2.3 GPG). No water softener is needed at this level.

What causes hard water in Colorado?

Hard water in Colorado is caused by dissolved calcium and magnesium from the local geology. Regional geology varies, with some areas having limestone bedrock that adds minerals and others with granite or sandstone that produces softer water.