Water hardness chart
Water hardness chart: gpg, ppm and what to do
How to read this: find your test result in either unit. Classes follow the U.S. Geological Survey scale (mg/L as calcium carbonate); 1 gpg = 17.1 ppm.
| Class | ppm (mg/L) | gpg | What to do |
|---|---|---|---|
| Soft | 0–60 | 0–3.5 | A softener isn't needed for scale. Spend on a filter if taste is the issue. |
| Moderately hard | 61–120 | 3.6–7 | Some scale and spotting. A small softener or a salt-free conditioner fits. |
| Hard | 121–180 | 7.1–10.5 | Visible scale on fixtures and heaters. A salt-based softener is worth it. |
| Very hard | over 180 | over 10.5 | Heavy scale. Use a salt-based softener sized with the calculator; salt-free units usually fall outside their stated limits. |
Embed this chart
Free to use on school, club and community sites with the credit link included. Copy this code:
<iframe src="https://besthomewatersoftener.com/embed/hardness-chart" width="100%" height="520" style="border:0" title="Water hardness chart"></iframe>
<p>Chart: <a href="https://besthomewatersoftener.com/guide">Best Home Water Softener</a></p>