Industry best practice manual for water quality management and sterilisation on-farm

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pH treatment

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
  • Optimal pH range for specific disinfect used in the system is determined.
  • pH is monitored directly before disinfection.
  • pH is adjusted to the optimal range before disinfection. See Table 14 (below) for examples of chemicals that can be used to adjust pH.
  • Measured pH is used in monthly Ct calculations.
    Best practice options
    Automated pH monitoring system.
    pH monitoring on:
  • inlet source water before treatment: indictor of source water quality changes,
  • before disinfection: as an indicator of disinfection efficiency, and
  • the inlet of each shed: as an indicator of pH changes in distribution lines.
  • Medium to high hardness in water:
  • reduce water pH to a range of 6.5 to 7, and
  • conduct acid treatment after each batch to remove scale.
  • 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/alkalineCalcium hydroxide (hydrated lime)

    Calcium oxide (quick lime)

    Sodium bicarbonate

    Sodium carbonate (soda ash)

    Sodium hydroxide (caustic soda)
    Decreases pH – acidicSulfuric acid

    Hydrochloric acid

    Formic acid

    Lactic acid

    Malic acid

    Tartaric acid

    Citric acid

    Orthophosphoric acid
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