Alkalinity Test of Water
High alkalinity quietly drives scale, corrosion, and chlorination inefficiency in drinking water and process water systems — and one out-of-spec result can hold up an FSSAI water source audit, a BIS ISI mark renewal, or a CPCB consent-to-operate review. Auriga Research delivers NABL-accredited alkalinity testing per IS 3025 Part 23 and IS 10500:2012, reporting total alkalinity, phenolphthalein alkalinity, bicarbonate, and carbonate fractions in mg/L as CaCO₃ on a single CoA.
Our scope covers the full IS 10500 alkalinity panel — acceptable limit 200 mg/L, permissible limit 600 mg/L in the absence of an alternative source — along with paired physical, chemical, and microbiological parameters (pH, hardness, chlorides, sulphates, fluorides, nitrates, total coliform, E. coli) on the same sample to deliver one report usable for FSSAI water source audits, BIS IS 14543 packaged water and IS 13428 mineral water compliance, CPCB / SPCB discharge norms, and pharmacopoeial Purified Water and WFI 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.
What Is the Alkalinity of Water?
Alkalinity is a measure of a water sample's capacity to neutralise acids — its ability to resist changes in pH. In natural water, alkalinity is primarily contributed by bicarbonate (HCO₃⁻), carbonate (CO₃²⁻), and hydroxide (OH⁻) ions. It is expressed as mg/L of CaCO₃ (calcium carbonate equivalent).
High alkalinity acts as a buffer, stabilising the water's pH against acidic inputs. This buffering capacity is critical in drinking water treatment (where it affects coagulation and disinfection), in industrial cooling and boiler systems (where it controls corrosion and scale), and in food processing (where it affects product pH and flavour).
| Alkalinity Type | Source Ions | End Point (pH) |
|---|---|---|
| Phenolphthalein Alkalinity (P) | Carbonate (CO₃²⁻) + Hydroxide (OH⁻) | 8.3 |
| Total Alkalinity (T) | Bicarbonate + Carbonate + Hydroxide | 4.5 |
| Bicarbonate Alkalinity (M) | Bicarbonate (HCO₃⁻) | 4.5 |
IS 10500 Alkalinity Limits for Drinking Water
IS 10500:2012 specifies the following limits for alkalinity in drinking water:
Acceptable Limit
200 mg/L
as CaCO₃
Recommended for normal drinking water supply
Permissible Limit
600 mg/L
as CaCO₃
Allowable only when no alternative source is available
How the Alkalinity Test of Water Is Performed
Alkalinity is determined by titrimetric analysis per IS 3025 Part 23. The method involves titrating a measured volume of the water sample with a standard sulphuric acid (H₂SO₄) solution to two different pH end points.
Phenolphthalein End Point (pH 8.3)
The sample is titrated with 0.02 N H₂SO₄ using phenolphthalein indicator until the pink colour disappears (pH 8.3). The volume used measures P-alkalinity — the carbonate and hydroxide fraction.
Total Alkalinity End Point (pH 4.5)
Titration continues with methyl orange or bromocresol green-methyl red indicator until the solution turns orange-red (pH 4.5). Total volume of acid used gives total alkalinity (T-alkalinity), covering bicarbonate, carbonate, and hydroxide together.
Calculation
Results are reported as mg/L CaCO₃. Bicarbonate alkalinity (M-alkalinity) = T − P. Carbonate alkalinity and hydroxide alkalinity are calculated from the P and M values using standard relationships.
Report
NABL-accredited test report with P-alkalinity, M-alkalinity (total alkalinity), and interpretation against IS 10500 limits. Reports are digitally signed and accepted by FSSAI, regulatory bodies, and industrial clients.
Why Alkalinity Matters — Applications
Drinking Water
- IS 10500 compliance for municipal and packaged water
- Corrosion control in distribution pipes
- Coagulant demand in water treatment plants
- FSSAI licence applications for food businesses using water
Industrial & Boiler Water
- Scale prevention in boilers and cooling towers
- pH stabilisation in industrial process water
- Corrosion rate assessment in cooling circuits
- Conductivity and cycles-of-concentration monitoring
Aquaculture & Environment
- Fish pond alkalinity monitoring (target 80–120 mg/L)
- River and lake water quality assessment
- Effluent compliance for CPCB/SPCB discharge norms
- Soil–water interaction in irrigation channels
Food & Pharmaceutical
- Process water for beverage and food manufacturing
- Purified water and WFI alkalinity in pharma systems
- Cleaning validation in GMP facilities
- Brewing and fermentation process water quality
How It Works
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.
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.
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.
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 Alkalinity Testing
NABL-accredited under ISO/IEC 17025:2017
Full IS 10500, IS 3025, IS 14543, IS 13428, and pharmacopoeial water scope — including titrimetric alkalinity per IS 3025 Part 23.
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 alkalinity.
Microbiology + chemistry on the same sample
Single CoA covering E. coli, coliform, TPC, pH, hardness, alkalinity, chlorides, sulphates, fluorides, and nitrates.
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.