Nearly 72% of Bengaluru gets contaminated water. Depending on whether residents get their water from borewells, tankers or from the Cauvery River, the quality varies from one area to another. According to a 2018 survey, 24% of Bengaluru households receive water from both borewells and Cauvery, with a hardness level above the prescribed limit of 200 milligrams per litre (mg/l).
Another study found Total Dissolvable Solids (TDS) range crossing 1,000 parts per million (PPM) per litre in Bengaluru, when the acceptable range is a maximum of 300 PPM. TDS refers to the amount of organic and inorganic material dissolved in water, which may include metals, salts, ions and minerals. Borewell and Cauvery water in areas like Yeshwanthpur, Nayandahalli and Bellandur also showed high levels of nitrate, fluoride and iron.
Moreover, Bengaluru’s tap water does not meet the standards set by the Bureau of Indian Standards (BIS). When water samples were tested for various organisms and toxic substances, Bengaluru fared poorly on all parameters.
The Central Ground Water Board (CGWB) ‘s Annual Groundwater Quality Report 2024 found high fluoride and uranium contamination in Karnataka, owing mainly to over-extraction, making borewell water unsafe for consumption.
“Bengaluru does not have complete aquifer mapping. If done, it would help us find pockets in the city that are safe to dig for groundwater. We don’t have resources to map which areas get recharged with the recharge-wells and tree-pits, so digging for borewells is never scientific in Bengaluru,” says Hari Prasad HK, senior research associate at Well Labs. He adds that while Cauvery water is generally of good quality, it often gets contaminated due to leakage from sewage pipelines.
Adverse health impacts
Contaminated tap water has made many city residents seriously ill, putting their health and safety at risk. At least 30 residents reported symptoms like loose stools, vomiting, and dehydration after consuming tap water on Promenade Road in Pulakeshinagara in February. Suspecting the water quality, they had it tested at a medical college hospital, which confirmed the presence of harmful bacteria, including E. Coli and Klebsiella Pneumoniae.
In Thanisandra, residents closed their valves due to sewage contamination in the Cauvery water pipelines in March and switched to tankers. “We have made several complaints to the BWSSB engineers. I’m not sure if they have taken the water for testing. For more than three months, we have been getting contaminated water,” said a resident of Thanisandra on anonymity.
Key parameters for testing water quality
Key physical, chemical and biological parameters have to be considered to test water quality in Bengaluru. Below are the essential parameters tested by BWSSB, Rural Drinking Water and Sanitation Department (RDW&SD) or NABL-accredited private labs:
Water quality parameters table
| Category | Parameter | Description/ Importance | Ideal/Preferred Level |
| 1. Biological | Total coliforms | Indicates a broader group of bacteria in water | Not specified |
| Faecal coliform / E. coli | Indicates faecal contamination and risk of waterborne diseases | 0 CFU/100 mL | |
| Pathogenic bacteria | e.g., Klebsiella, Salmonella | Not always routinely tested | |
| 2. Chemical | Major Ions | ||
| Hardness | Presence of calcium and magnesium; scaling in pipes | <200 mg/L | |
| Chloride | Indicates dissolved salts; can reflect pollution or saline intrusion | <250 mg/L | |
| Total Alkalinity | Water’s buffering capacity, indicating its ability to resist changes in pH | pH 6.5–8.5 | |
| Dissolved Oxygen (DO) | Low DO indicates pollution | >5 mg/L | |
| Total Dissolved Solids (TDS) | Measures all dissolved substances | <500 mg/L (up to 2000 in emergencies) | |
| Sulfates | High levels can cause laxative effects | <200 mg/L | |
| Nutrients & Contaminants | |||
| Nitrates | Harmful at high levels, especially to infants | <45 mg/L | |
| Fluoride | Beneficial in range; high range can cause fluorosis | 0.6–1.2 mg/L (max 1.5 mg/l) | |
| Iron | Causes staining and taste issues | <0.3 mg/L | |
| Manganese | Can affect taste and colour, and stain laundry | <0.1 mg/L | |
| Ammonia | High levels indicate sewage contamination | Ideally 0 | |
| Toxic Heavy Metals | |||
| Lead | Causes neurological damage | <0.01 mg/L | |
| Arsenic | Carcinogenic with long-term exposure | <0.01 mg/L | |
| Mercury, Cadmium, Chromium | Industrial contaminants; tested if relevant | As per local standards | |
| 3. Physical | Temperature | Affects dissolved gas solubility and aquatic life activity | <25°C preferred |
| Turbidity (cloudiness/haziness) | Indicates presence of suspended particles | <1 NTU (Nephelometric Turbidity Units) | |
| Taste and Odour | Should be non-objectionable | None detectable | |
| 4. Other Parameters | Chemical Oxygen Demand (COD) | Oxygen required to oxidise organic matter chemically | Lower values preferred |
| Biochemical Oxygen Demand (BOD) | Oxygen used by microbes to break down organic matter | <3 mg/L ideal for drinking water |
Source: BWSSB and RDW&SD
Who tests water quality in Bengaluru?
Several government bodies and accredited laboratories test water quality in Bengaluru:
The BWSSB conducts monthly testing of Cauvery water to ensure compliance with Indian Standards (IS) and WHO guidelines. The Board collects 16 samples from treatment plants, reservoirs, and consumer endpoints. An online water quality monitoring system provides real-time data on key parameters, allowing quick responses to deviations. Sensors at strategic locations, including Sewage Treatment Plants (STP), transmit data to a central monitoring station for continuous quality checking.
BWSSB has three labs in Bengaluru, at High Grounds, Jayanagara and OMBR Layout, which are equipped to conduct comprehensive analyses of water samples. BWSSB also has mobile testing laboratories, which are vans fitted with kits to analyse water samples collected at random spots.
Read more: Digging a borewell in Bengaluru? Here’s a guide to groundwater extraction rules
The RDW&SD conducts regular water testing and responds to complaints in Bengaluru Rural. They carry out field-level assessments and detailed laboratory analyses.
- Field-level testing: At the grassroots level, RDW&SD collaborates with Village Water and Sanitation Committees (VWSCs) to conduct preliminary water quality assessments to measure basic chemical and biological contamination. If these initial tests indicate potential contamination, samples are forwarded to district-level laboratories for comprehensive analysis.
- Laboratory testing: RDW&SD has established dedicated water quality testing laboratories in both Bengaluru Urban (in Banashankari) and Rural districts (in Doddaballapur). Comprehensive analyses adhering to chemical, biological and physical parameters is done here.
RDW&SD mandates water quality testing at least twice annually, specifically before and after the monsoon season. However, additional testing drives can be initiated in response to specific concerns.
How can you test your water?
The BWSSB Public Relations Office and RDW&SD officials explained the process by which you can test your water in Bengaluru Rural and Urban districts.
- BWSSB mostly tests water in the city limits. You can visit the service station or the Assistant Executive Engineer’s (AEE) office in your ward to complain about your water quality. After an initial test, the Quality Assurance team will collect your water sample (approximately two litres) and analyse it for various parameters at any of their labs. You will get the result in 48 hours. If your water is contaminated, BWSSB will immediately halt the supply to rectify the problem, and till then, you will be provided tanker water for your needs. BWSSB doesn’t charge for the services. Find water quality reports for various parts of the city here.
- Several private NABL-accredited water testing laboratories like Prewel Labs, SLN Testing Laboratory and Ion Exchange India offer to test your borewell water quality at individual household levels. You can find the full-list here. Pricing varies from one lab to another.
- RDW&SD conducts water quality tests in Bengaluru Rural. You can visit the District Water Quality Testing Laboratory or contact the valve person/AEE in your ward to report concerns. Alternatively, call the helpline at 8277506000.
- RDW&SD collects at least one litre of water from common points in gram panchayats for analysis, with results available in 3–4 days. If contamination is found, supply is halted, and the gram panchayat is notified. Alternative water sources will be provided until the issue is resolved.
- Testing of public water is free, while private property tests incur charges. RDW&SD also has a list of empanelled NABL-accredited laboratories for further testing.
- Hari Prasad suggests DIY water quality testing using probes, available from companies like Vasa Scientific in Bengaluru, priced between ₹1,000 and ₹5,000. The preliminary test should cover these key elements, with the probe aiding in TDS and pH measurement:
* Colour: Should be clear
* Smell: Non-objectionable
* pH: Ideally 7 (neutral)
* TDS: below 500 ppm
* Total Suspended Solids (TSS): No visible haziness or suspended particles
* Taste: The final check, only if the previous parameters meet safe levels.
Have you ever tested your water supply for contaminants? Let us know in the comments.