Delhi · Gurugram · Bangalore · Baddi · Bahadurgarh

Turbidity Test of Water

Turbid water silently undermines disinfection efficacy — even routine chlorination can fail at turbidities above 5 NTU, leaving residential, food-grade, and bottled-water supplies exposed to Cryptosporidium, Giardia, and coliform breakthroughs. Auriga Research provides NABL-accredited turbidity testing per IS 10500:2012 and IS 3025 Part 10, by calibrated nephelometric measurement on instruments traceable to NIST formazin standards, for drinking water, bore wells, packaged water, industrial process water, and pharmaceutical systems.

Our scope covers the full IS 10500 turbidity panel — acceptable limit 1 NTU, permissible limit 5 NTU in the absence of an alternative source — along with paired physical and microbiological parameters (pH, TDS, total coliform, E. coli) on the same sample to deliver a single CoA usable for FSSAI water source audits, BIS IS 14543 packaged water compliance, CPCB / SPCB discharge norms, and pharmacopoeial water systems under IP, USP, EP, and BP.

Backed by the Arbro Group's unbroken NABL accreditation since 2003, our reports are accepted by FSSAI regional offices, BIS licensing authorities, CPCB / SPCB, municipal water utilities, and major packaged drinking water brands across India.

Reports in 3–5 working days | Express: 1–2 days available
Get a Quote Call +91-7428116100

What Is the Turbidity of Water?

Water contains suspended solids of varying sizes. Larger particles settle under gravity — these are settleable solids. Smaller colloidal particles remain suspended and cause water to appear turbid. When light passes through turbid water, particles scatter the beam in multiple directions; a nephelometer measures the intensity of this scattered light at 90 degrees to the incident beam.

Turbidity is expressed in NTU (Nephelometric Turbidity Units). Values below 1 NTU are typical of well-treated drinking water; values above 10 NTU indicate significant turbidity that is visible to the naked eye and potentially unsafe for drinking without treatment.

Turbidity Level (NTU) Interpretation
< 1 NTU Excellent — meets IS 10500 and WHO drinking water standard
1–5 NTU Acceptable — IS 10500 permissible limit (no alternative source); monitor and treat
5–10 NTU Marginal — exceeds IS 10500 limit; treatment required before consumption
10–50 NTU High turbidity — significant particulate load; treatment essential
> 50 NTU Very high — not suitable for drinking; indicates major contamination

Causes of Turbidity in Water

  • Soil erosion and agricultural runoff — clay, silt, and fine soil particles
  • Urban storm water from roads, construction sites, and paved areas
  • Algal growth in reservoirs, lakes, and open water bodies
  • Industrial effluent containing suspended solids
  • Resuspension of bottom sediments during heavy rainfall or flooding
  • Sewage or septic system contamination entering water sources
  • Bore well contamination — defective casing or drilling residues
  • Decaying organic matter and leaf litter in surface water

Turbidity Testing Method — Nephelometric Measurement

The standard method for turbidity measurement is the nephelometric method per IS 3025 Part 10 (Indian Standards for Water Quality). A turbidimeter (nephelometer) illuminates the water sample with a light beam and measures the intensity of scattered light at exactly 90 degrees to the incident beam.

Instrument: A nephelometer with a light source, photoelectric detector, and readout device. The instrument is calibrated using formazin standards (Formazin Attenuation Units, FAU) or equivalent AMCO-AEPA polymer standards traceable to primary formazin. The range for the method is 0–40 NTU; higher turbidity samples require dilution before measurement.

Sample requirements: 10–25 mL of clear, undisturbed water in a clean borosilicate glass cell. Samples should be measured within 24 hours of collection. Avoid introducing air bubbles, as these cause false high readings.

How It Works

1

Get a Quote

Share your water source type and the parameters or regulatory requirement needed. Your SPOC confirms the exact scope and sample collection requirements for your use case.

2

Collect and Send Your Sample

Collect water in Auriga-provided containers — sterile bottles for microbiological parameters, HDPE bottles for chemical testing. Samples must reach the lab within 24 hours of collection for microbiological parameters. Each sample is bar coded and registered in YLIMS on receipt.

3

Testing and QA Review

Your sample is tested against the confirmed method (IS 10500, IS 3025, IS 14543, CPCB, or pharmacopoeial as applicable). All results pass through formal internal QA review before the report is generated.

4

Receive Your NABL Report

Your NABL-accredited report is delivered digitally within the committed TAT, accepted by FSSAI, BIS, CPCB, and state regulatory authorities. Track status via YLIMS throughout the process.

Who Needs This Testing

  • Packaged drinking water plants needing BIS IS 14543 ISI mark certification and renewal.
  • Mineral water producers under BIS IS 13428 licence audit.
  • Municipal corporations, RWAs, and water utilities monitoring distributed supply against IS 10500.
  • Food and beverage manufacturers running FSSAI water source audits and water-as-ingredient verification.
  • Hotels, hospitals, QSRs, and food service chains running periodic water quality surveillance.
  • Industrial facilities (cooling tower, boiler feed, process water, effluent) under CPCB / SPCB consent.
  • Pharmaceutical and CDMO units running Purified Water and WFI loop validation per USP <1231> / IP / BP / EP.
  • Construction, real estate, and infrastructure projects needing pre-occupancy water quality certificates.

Why Auriga for Turbidity Testing

NABL-accredited under ISO/IEC 17025:2017

Full IS 10500, IS 3025, IS 14543, IS 13428, and pharmacopoeial water scope — turbidity by calibrated nephelometric method per IS 3025 Part 10.

BIS-recognised / FSSAI-notified

Reports accepted for ISI mark applications, FSSAI water source audits, and CPCB consent-to-operate.

ICP-MS for trace heavy metals

Lead, arsenic, cadmium, mercury, and uranium quantified below IS 10500 limits on the same sample alongside turbidity and microbial counts.

Microbiology + chemistry on the same sample

Single CoA covering E. coli, coliform, TPC, pH, hardness, alkalinity, chlorides, sulphates, fluorides, and nitrates with the turbidity result.

Five regional labs across India

Delhi, Gurugram, Bangalore, Baddi, and Bahadurgarh — fast local turnaround and 24-hour sample receipt for microbiological holding times.

Arbro Group NABL accreditation since 2003

Two decades of continuous ISO/IEC 17025 conformity — the audit trail BIS, FSSAI, CPCB, and municipal authorities look for.

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Frequently Asked Questions — Turbidity Testing

What is turbidity in water?
Turbidity is the cloudiness or haziness of water caused by suspended particulate matter — including sediment, clay, silt, finely divided organic material, algae, and microscopic organisms. Turbidity is measured by the degree to which a beam of light passing through the sample is scattered by suspended particles. The unit of measurement is NTU (Nephelometric Turbidity Units) or FTU (Formazin Turbidity Units). High turbidity makes water appear cloudy, brown, or green depending on the particulate type.
What is the permissible turbidity limit in drinking water per IS 10500?
IS 10500:2012 (Indian Standard for Drinking Water Specification) sets the acceptable limit for turbidity at 1 NTU for drinking water. The permissible limit in the absence of an alternative source is 5 NTU. The World Health Organisation (WHO) guideline value is also 1 NTU. For swimming pools, CPCB and BIS standards typically require turbidity below 0.5–1 NTU. Higher turbidity is permitted for industrial and non-potable applications depending on end use.
How is turbidity measured in the laboratory?
The standard laboratory method for turbidity measurement is the nephelometric method, in which a calibrated turbidimeter (nephelometer) measures the intensity of light scattered at a 90-degree angle relative to the incident beam. The sample is placed in a clear glass or plastic cell; the instrument illuminates the sample and measures the scattered light. Results are reported in NTU. The method conforms to IS 3025 Part 10 for Indian water quality testing. Turbidimeters are calibrated using formazin standards traceable to NIST.
Why is turbidity a health concern in drinking water?
Turbidity itself is not a direct health risk, but it is a critical indicator of potential microbial contamination. Suspended particles in turbid water can shelter bacteria, viruses, and protozoa (like Cryptosporidium and Giardia) from disinfection by chlorine or UV treatment. High turbidity significantly reduces disinfection efficacy — at turbidities above 1–5 NTU, even standard chlorination may fail to inactivate all pathogens. The IS 10500 turbidity limit of 1 NTU provides a safety margin to ensure effective disinfection.
What causes high turbidity in water?
High turbidity in water can be caused by: soil erosion and agricultural runoff (clay, silt, sand); urban storm water runoff from roads and construction sites; algal blooms in reservoirs; industrial effluent discharge; resuspension of settled sediment by flooding or high flow; sewage contamination; decomposition of organic matter; and, in groundwater, bore well contamination or improper casing. Seasonal variation is common — turbidity peaks during monsoon in surface water sources.
When should I test water for turbidity?
Turbidity testing is recommended: before using a new bore well or water source; after heavy rainfall or flooding (surface water contamination risk); if water appears cloudy, brown, or has an earthy/musty odour; for FSSAI food business licence applications (water used in food processing must meet quality standards); before installing or after servicing water treatment equipment; for packaged drinking water compliance per IS 14543; for industrial process water quality monitoring; and for pharmaceutical water systems (purified water, WFI).

Get Your Water Tested for Turbidity

NABL-accredited turbidity testing and full IS 10500 water quality analysis. Pan-India collection. FSSAI-compliant reports.

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