From ppm to milligrams
Because a litre of water weighs about a kilogram (a million milligrams), one part per million works out at about one milligram per litre. That makes the conversion simple:
| Concentration | Silver per litre | Silver per 100ml | Silver per 500ml |
|---|---|---|---|
| 5ppm | ≈ 5mg | ≈ 0.5mg | ≈ 2.5mg |
| 10ppm | ≈ 10mg | ≈ 1mg | ≈ 5mg |
| 20ppm | ≈ 20mg | ≈ 2mg | ≈ 10mg |
| 30ppm | ≈ 30mg | ≈ 3mg | ≈ 15mg |
How is ppm measured?
Small producers usually check each batch with a conductivity (TDS) meter. Dissolved silver ions conduct electricity, so the reading rises as the concentration rises. Because the water starts out deionised, almost all of that conductivity comes from the silver. A conductivity reading mainly reflects the dissolved (ionic) part, though. For a full figure that also includes metallic particles, laboratories use methods such as ICP or atomic absorption spectroscopy.
Is a higher ppm better?
Not necessarily. ppm is a measure of concentration, not quality. Very high figures can also mean larger particles, which tend to give a darker colour and are more likely to settle over time. What matters more is that the figure is consistent and actually measured, and that the product contains nothing but water and silver. We make one strength, 10ppm, and check every batch so that each bottle matches the label.
Why brands quote different ppm figures
Makers choose different strengths, and they also measure in different ways. One brand may quote the ionic reading from a conductivity meter, another a laboratory total, and some quote a target rather than a measured value. If a figure matters to you, ask the maker how they measured it.