Know the label before you refill
Purified vs. alkaline water: what is the difference?
Short answer: “Purified” describes water that meets a treatment-based standard. “Alkaline” describes water with a pH above neutral. Water can be both purified and alkaline, so the terms are not opposites.
| Label | What it tells you | What it does not prove |
|---|---|---|
| Purified | The water meets a treatment-based standard; reverse osmosis, distillation and deionization are named processes. | That one treatment method is automatically best for every person or use. |
| Alkaline | The water is above neutral on the pH scale. | That the water is purer, safer or medically beneficial. |
| Spring | The label describes the water’s source under federal rules. | That the water is untreated, contaminant-free or alkaline. |
What “purified” means
The FDA says bottled water treated by distillation, reverse osmosis or another suitable process may meet the standard that allows it to be labeled “purified water.” The label is about the resulting standard and treatment—not a universal promise about taste or health.
What “alkaline” means
The U.S. Geological Survey explains that pH runs from 0 to 14, with 7 neutral and values above 7 considered alkaline, or basic. pH is one water property. It does not tell you, by itself, how the water was treated.
Which should you choose?
Choose based on the information you care about. If treatment is your priority, ask how purified water is produced and how the equipment is maintained. If you prefer alkaline water, ask for the target pH and whether minerals are added after purification. Taste preferences can also differ.
Five questions to ask a refill provider
- Which treatment process is used?
- How often is the equipment serviced?
- Is alkaline water purified before its pH is adjusted?
- How are refill bottles sanitized?
- Which bottle sizes can be refilled, and what should customers bring?
Sources
- U.S. Food and Drug Administration: bottled water treatment and labeling ↗
- U.S. Geological Survey: pH and water ↗
Updated August 12, 2026. General consumer information; not medical advice.