Water Turbidity

AUS-ASC-FOR-WTU General Moderate confidence

Benchmark Value

1 NTU

Thresholds: Lower: —, Upper: 1

Direction: Lower is desirable ↓

Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 13 benchmarks together — the OptimalRange form drives the primary score, while 12 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard MinimumOnly Guard MaximumOnly Guard Point Guard OptimalRange Guard MaximumOnly Guard UpperThreshold Guard Point Guard Point Guard MaximumOnly Guard OptimalRange Guard UpperThreshold Guard

Evidence & Context

The Australian Drinking Water Guidelines state that a turbidity of less than 1 NTU is desirable at the time of disinfection with chlorine.

Metric Definition:

Nephelometric turbidity

Benchmark Definition:

Turbidity less than 1 NTU is required for effective chlorine disinfection in drinking water.

Justification:

Critical for ensuring effective chlorination and reducing risk from protozoan pathogens.

Sources (1)

Preview of Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 11, 2025,

Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 11, 2025, Government

Australian Drinking Water Guidelines

Supporting Sources (23)

Additional references from the underlying research that informed this benchmark.

Preview of 1.1.5.2 Surface water quality - Bioregional Assessments |, accessed August 5, 2025,

1.1.5.2 Surface water quality - Bioregional Assessments |, accessed August 5, 2025,

Direct Evidence Government

Bioregional Assessment. (2018). Surface water quality - Gippsland Basin bioregion.

Preview of An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria - MDPI, accessed August 1, 2025,

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria - MDPI, accessed August 1, 2025,

Direct Evidence Journal

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria

Preview of Assessing Water Quality - Secondary Education Years 9 to 12 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Assessing Water Quality - Secondary Education Years 9 to 12 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Direct Evidence Journal

Assessing water quality - ACT Waterwatch

Preview of Catchment Health Indicator Program Report (CHIP) 2022 - Upper ..., accessed July 16, 2025,

Catchment Health Indicator Program Report (CHIP) 2022 - Upper ..., accessed July 16, 2025,

Contextual Support Journal

ACT Waterwatch. (2023). Catchment Health Indicator Program Report 2023.

Preview of Catchment Health Indicator Program Report 2021 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Catchment Health Indicator Program Report 2021 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Contextual Support Journal

ACT Waterwatch. (2022). Catchment Health Indicator Program Report 2022.

Preview of Default guideline values - Water Quality Australia, accessed August 12, 2025

Default guideline values - Water Quality Australia, accessed August 12, 2025

Contextual Support Government

Bioregional Assessment. (2014). Surface water quality - Gwydir subregion.

Preview of Desktop review – Impact of bushfires on water quality, accessed August 10, 2025,

Desktop review – Impact of bushfires on water quality, accessed August 10, 2025,

Contextual Support Journal

Southern New England Landcare. (n.d.). Water Quality on New England wool properties.

Preview of DRINKING WATER QUALITY ANNUAL REPORT 2022-2023, accessed August 17, 2025,

DRINKING WATER QUALITY ANNUAL REPORT 2022-2023, accessed August 17, 2025,

Direct Evidence Journal

ANZG. (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Preview of Feral horses (Equus caballus) increase suspended sediment in subalpine streams

Feral horses (Equus caballus) increase suspended sediment in subalpine streams

Contextual Support GreyLiterature

Robertson, G., et al. (2021). Feral horses (Equus caballus) increase suspended sediment in subalpine streams. Marine and Freshwater Research.

Preview of Feral horses increase suspended sediment in subalpine streams

Feral horses increase suspended sediment in subalpine streams

Contextual Support Journal

Feral horses increase suspended sediment in subalpine streams

Preview of In-Situ Support. (2024). What are typical turbidity values in natural environments?

In-Situ Support. (2024). What are typical turbidity values in natural environments?

Methodology Source GreyLiterature

Hanna Instruments Australia. (2024). The Complete Guide to Measuring Turbidity in Water.

Preview of Logging Impacts On Streams - Cloudfront.net

Logging Impacts On Streams - Cloudfront.net

Direct Evidence Journal

North East Forest Alliance (NEFA). (n.d.). Logging Impacts On Streams.

Preview of NHMRC. (2011). Australian Drinking Water Guidelines - Part 5 Physical and Chemical Characteristics: Turbidity.

NHMRC. (2011). Australian Drinking Water Guidelines - Part 5 Physical and Chemical Characteristics: Turbidity.

Contextual Support GreyLiterature

Ketos. (2024). Acceptable Turbidity Levels in Industrial Water.

Preview of North Esk Water Quality Study - Part 1

North Esk Water Quality Study - Part 1

Direct Evidence Journal

North Esk Water Quality Study - Part 1

Preview of NSW Water Quality Index Targets

NSW Water Quality Index Targets

Direct Evidence Journal

NSW Department of Climate Change, Energy, the Environment and Water. (2025). Targets to develop a water quality index for NSW rivers - River condition index.

Preview of Protecting waterways - Forestry Corporation, accessed July 12, 2025,

Protecting waterways - Forestry Corporation, accessed July 12, 2025,

Direct Evidence Government

Forest Town Nature Conservation Group. (2024). Spa Ponds Water Quality.

Preview of Turbidity layer thresholds - WikiWatershed

Turbidity layer thresholds - WikiWatershed

Direct Evidence Journal

WikiWatershed. (2021). Layering Thresholds for Turbidity.

Preview of U.S. EPA. (2022). Turbidity Benchmark Monitoring for Dewatering under the Construction General Permit.

U.S. EPA. (2022). Turbidity Benchmark Monitoring for Dewatering under the Construction General Permit.

Contextual Support Journal

Tasmania Department of Primary Industries, Water and Environment. (2003). North Esk Water Quality Study - Part 1.

Preview of Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Contextual Support Journal

Alpine Resorts Victoria. (2023). ARV Water Quality Annual Report 2022-23.

Preview of Victoria Environment Protection Authority. (2018). State Environment Protection Policy (Waters).

Victoria Environment Protection Authority. (2018). State Environment Protection Policy (Waters).

Regulatory Framework Government

Victoria Environment Protection Authority. (2018). State Environment Protection Policy (Waters).

Preview of Victoria Government. (2021). Environment Reference Standard.

Victoria Government. (2021). Environment Reference Standard.

Contextual Support Journal

Victoria Government. (2021). Environment Reference Standard.

Preview of Water Quality Objectives - Border Rivers - NSW Government

Water Quality Objectives - Border Rivers - NSW Government

Direct Evidence Government

Bioregional Assessment: Gippsland Basin - Surface Water Quality

Preview of Webb, A. A., & Turner, L. (2004). Impact of mitigated forestry activities on turbidity: assessing the effect of improved harvesting practices.

Webb, A. A., & Turner, L. (2004). Impact of mitigated forestry activities on turbidity: assessing the effect of improved harvesting practices.

Direct Evidence Journal

Webb, A. A., & Turner, L. (2004). Impact of mitigated forestry activities on turbidity: assessing the effect of improved harvesting practices.