Table 6 Classification of water quality for industrial use

From: Assessment of water quality and suitability analysis of River Ganga in Rishikesh, India

RSI Inference (Ryznar 1944) RSI Inference (Carrier 1965)
<5.5 Heavy scale will form 4–5 Heavy scale
5–6 Light scale
5.5–6.2 Scale will form 6–7 Little scale or corrosion
6.2–6.8 No difficulties 7–7.5 Corrosion significant
6.8–8.5 Water is aggressive 7.5–9 Heavy corrosion
>8.5 Water is very aggressive >9 Corrosion intolerable