Low-level turbidity measurements: A comparison of instruments

Raymond D. Letterman, Chris E. Johnson, Sudhakar Viswanathan

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


With more and more stringent regulatory requirements being imposed on the drinking water industry, it is increasingly important to ensure that standards are being met. This means that water treatment plants and their managers rely heavily on measurement equipment to ensure that quality standards are being met. With regard to particle removal, it has been observed that the type of turbidimeter determines the reading, and that - especially at low turbidity levels - the differences in readings can be significant. Because low-level turbidity measurements are used for regulatory purposes, it is important that measurements from different instruments be in rea sonable agreement, but it has been discovered that they are not. In conducting this study, the authors came to two major conclusions: (1) different turbidimeters used at treatment plants may not agree when measuring the same sample and (2) the measurements are not significantly affected by the type of calibration material used. As a result of this study, the authors suggest that there needs to be a better process for approving or certifying turbidimeters. Until there is, the information in this article will at least alert utility managers to this problem and provide them with information on using proper measurement techniques.

Original languageEnglish (US)
Pages (from-to)125-137+14
JournalJournal / American Water Works Association
Issue number8
StatePublished - Aug 2004

ASJC Scopus subject areas

  • General Chemistry
  • Water Science and Technology


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