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Delhi’s water supply depends on three sources – the Upper Ganga Canal, groundwater, and the Yamuna. Every source has a different contamination profile – some are prone to microbiological contamination, others to high TDS levels. The water your tap brings depends largely on the treatment plan serving your area.
Most water quality advice in Delhi overlooks this. It sorts the city by zones and quotes a single TDS range for each area. But water does not follow – it follows treatment plants. Two houses within a kilometre can have water from different supplies, with two distinct problems.
Where Does the Delhi Water Supply Come From?
Delhi’s water supply barely relies on Delhi itself.
- Roughly 389 MGD comes from the Yamuna.
2. About 253 MGD comes from the Ganga via the Upper Ganga Canal.
3. Around 221 MGD comes from Bhakra storage on the Ravi–Beas system.
4. Roughly 90 MGD of groundwater makes up the rest.
Over 90% of Delhi’s water originates outside the city, especially from Himachal Pradesh, Haryana, and Uttar Pradesh. According to the Delhi Jal Board, the authority can produce 916 MGD of water through about 9,000 km of pipelines, but the demand is usually 1,150 MGD or more. This is the reason the supply gap exists, and exactly why it matters where the water comes from.
Delhi’s Water Treatment Plants and their Sources
| Raw Water Source | Treatment Plants | Capacity | Key Characteristic |
| Yamuna River | Wazirabad | ~124 MGD | Most variable source; abstracted downstream of Haryana’s releases; ammonia spikes force periodic shutdowns |
| Yamuna River | Chandrawal | ~98 MGD (peak) | Same river source as Wazirabad; shares ammonia-related shutdown risk |
| Canal Water | Sonia Vihar | 144 MGD | Draws from Upper Ganga Canal at Muradnagar; steadier turbidity than river water |
| Canal Water | Bhagirathi | 100 MGD | Draws from Upper Ganga Canal at Muradnagar |
| Canal Water | Haiderpur | 220 MGD | Draws from Western Yamuna Canal, which also carries Delhi’s Bhakra allocation |
| Canal Water | Nangloi | 40 MGD | Draws from Western Yamuna Canal |
| Canal Water | Dwarka | 46.5 MGD | Draws from Western Yamuna Canal |
| Groundwater | Ranney wells (Palla floodplain) | ~90 MGD | Combined with ~4,000 tubewells and private borewells that activate when piped supply falls short |
Note: When upstream transfers dip, borewells and tankers fill the gap — water that isn’t treated to the same standard as plant-supplied water.
Is Drinking Water in Delhi Safe?
No, the water needs to undergo a purification process to be safe to drink. According to a 2019 Bureau of Indian Standards survey of piped tap water in state capitals, all 11 samples from Delhi failed to meet the drinking water standard.
TDS in Delhi Water: What Should Your Water Purifier Remove?
Delhi’s three raw water sources do not pass different tests. The right water purifier for a Delhi home depends on the water source. RO is usually recommended for groundwater with high TDS levels, and UV and UF for low TDS levels.
High TDS Levels Need RO
Across different parts of Delhi where groundwater is the primary source, TDS runs from 700 mg/L to above 2,00 mg/L. BIS IS 10500 sets the permissible limit for TDS at 500 mg/L, with 2,000 mg/L as the outer permissible limit where no alternative water source is available.
If the TDS reading is above 500 mg/L, it is the clearest signal your home needs an RO Purifier. A UV or carbon filter cannot singlehandedly treat the water. When the water has such a high TDS, it needs a membrane. UV or UF cannot remove dissolved salts.
Low TDS Levels Need UV and UF
RO strips minerals that your body needs. Water coming from Haiderpur or Sonia Vihar undergoes filtration, chlorination, and coagulation. This way, the TDS range is significantly reduced and is inside the acceptable limit.
However, the main risk here is not the total dissolved solids. Water comes from ageing pipes, and the contamination entering the system between the plant and the tap is biological. Ultraviolet (UV) and Ultrafiltration (UF) manage it; RO cannot do it alone.
Renting or Buying a Water Purifier in Delhi
A purchased water purifier is a permanent fixture. It is in accordance with the TDS levels in your building. However, it may be a problem for Delhi’s water supply because the supply changes mid-year. With the supply rotating between plants, many buildings fall back on borewells. A water purifier designed for 250 ppm (when the source was canal water) is not effective when the borewell delivers 1,100 ppm.
Water Purifier Monthly Subscriptions
With changing water sources, the quality of water in Delhi also changes. This is a reason many households prefer water purifier subscriptions to buying outright. Rental service providers have started offering multi-stage RO purifiers with UV and UF filters, mineral enhancers, or even alkaline filters on monthly plans. Anyone comparing a water purifier on rent against buying must stack the features and monthly pricing to understand its feasibility.
Final Thoughts
There is no single answer for Delhi’s water supply because of its varied water sources. Homes with Wazirabad or Chandrawal face different water sources, and there are sometimes ammonia shutdowns. If you live in Sonia Vihar, Haiderpur, or Bhagirathi, you still have a steady supply of canal water. However, microbiological contamination cannot be ruled out. This is why a single filtration logic does not work across Delhi. That’s why you should choose a water purifier based on the TDS readings from your building.