Summary of the City
Delhi receives 86% of water through Surface Water, namely the Yamuna River, and the remaining from tributaries of Ganga River.

Water Quality Information

Delhi City
The WYC (Western Yamuna Canal) crosses Yamuna Nagar, Karnal and Panipat before reaching the Haiderpur treatment plant (which supplies part of Delhi's water), receiving wastewater from Yamuna Nagar and Panipat. Haryana's vast agricultural fields are also significant contributors to pollute Yamuna before entering Delhi.
Untreated waste water and industrial effluents are routinely discharged into Delhi's water bodies. The Yamuna River, near Delhi, is an important source of drinking water for downstream cities. But it has been an open sewer for decades.

Delhi NCR
Faridabad
To city 80 MLD water being supply through 1,411 tube wells & 120 MLD supply from 14 Rainey wells operating from the Yamuna riverbed in the district. Most of the residence claims that they received water quality of washing & bathing not for drinking.

Ghaziabad
The district of Ghaziabad is situated in the middle of Ganga-Yamuna doab. A test carried out to judge the quality of drinking water in the city by Ghaziabad Municipal Corporation found 700 samples out of 1,000 unfit for human consumption.

Gurgoan
The main drinking water source of Gurgoan which is ground water getting more worst day by day. Mainly the Chloride, Fluoride & Nitrate level increases beyond permissible limit. According to Central Ground Water Authority main reasons behind it illegal extraction of ground water, the depletion of the aquifer because of contraction of recharge zones & contamination from the defunct Bandhwari waste treatment plant continuously unchecked.

Noida
Main source of water for domestic use of Noida is ground water. But due to high hardness level, every day, the industrial hub of Noida uses 48 million liters of Ganga water to dilute hard groundwater, making it safe for residents to use.

An analysis by M/s WAPCOS (Water & Power Consultancy Services (India) Ltd.), a Government of India undertaking consultancy, has found that for every 222 MLD (million litres per day) of groundwater extracted by the city, 84 MLD of Ganga water is required to make it usable.

Recommended Technology
For Delhi Jal board (MCD) -
For less maintenance & water wastage - UF / UF+UV
For more purity - NF 30 + UV (Maintenance & water wastage will be high)
For Delhi NCR - (NF 30 / NF 60 / RO) + UV [Depends upon water source, Municipal & Ground water Mixing ratio, TDS & Pollution level, etc;]