| Performance goal: Water treatment achieves optimal pH for disinfection and scale minimisation. |
|---|
| Description: The pH of pure water is 7 and is neutral. Water with a pH lower than 7 is considered acidic, while water with a pH greater than 7 is considered alkaline (basic). The normal pH range of surface water is 6.5 to 8.5. Bore water pH usually ranges from 6 to 8.5. Rainwater is usually slightly acidic. Some pathogenic microorganisms are sensitive to pH; however, this is not a sufficient control measure. Acidification (pH reduction) is a water treatment used to promote healthy gut flora, correct water pH and control scale. Acidification is not to be used instead of disinfection. Acidic pH can cause metal leaching and corrosion of metal pipes, soldering, nipples and pump components. The rate of corrosion depends on the type of metal and the pH. |
| Performance criteria: Optimal water pH levels are achieved and maintained. Best practice range: pH 6.5–7.8 Maximum acceptable range: pH 6.5–8.5 |
| Minimum requirements |
| Measured pH is used in monthly Ct calculations. |
| Best practice options |
| Automated pH monitoring system. |
| pH monitoring on: |
| Medium to high hardness in water: |
| Replacement chemicals, and other associated consumable products on standby. |
| Backup power and duplicate facilities treat water. |
Other information
Table 14. Examples of chemicals that can be used to adjust pH
| pH effect | Treatment chemical |
|---|---|
| Increases pH – basic/alkaline | Calcium hydroxide (hydrated lime) Calcium oxide (quick lime) Sodium bicarbonate Sodium carbonate (soda ash) Sodium hydroxide (caustic soda) |
| Decreases pH – acidic | Sulfuric acid Hydrochloric acid Formic acid Lactic acid Malic acid Tartaric acid Citric acid Orthophosphoric acid |
