Why water could decide the Indian elections

India is the world's second largest country by population (1.2 billion) and tenth largest by GDP ($1,842bn), yet the national election next month could be decided by a simple issue – water.

Mechanically pumped groundwater now provides 85% of India's drinking water, and is the main water source for all uses. North India's groundwater is declining at one of the fastest rates in the world, and many areas may have already passed "peak water". The World Bank predicted earlier this year that a majority of India's underground water resources will reach a critical state within 20 years. Groundwater use still falls under an 1882 colonial law, but the reasons behind its dramatic decline are more to do with the local and international politics of water management.

New Delhi has an average water supply – 273 litres per person per day – which is higher than London and Paris, but simply accessing water is a daily challenge for about 50% of residents. As the city water board struggles, Delhi's thirsty population depends on the "water mafia", said to control a trade worth billions of dollars that is essential for ordinary people, wealthy residents and elected politicians alike. Just as onion prices rise before an election, tensions over water run high, increasing general anti-incumbency bias and voter loyalty towards those able to deliver on promises of good supply. The brokerage chains used in Indian cities to arrange water access can both support existing political regimes and lead to resentment against them.

Until now, the 2014 elections have been shaping up to be a head-to-head battle between leaders of the two main parties: Narendra Modi's hi-tech hindutva for the BJP, against Rahul Gandhi, scion of the Nehru dynasty, for the somewhat tarnished Congress. The dark horse in the national campaigning, though, is India's newest political party the Aam Aadmi (AAP) led by an unlikely frontman, former civil servant and water activist Arvind Kejriwal.

The AAP won a surprise victory in the recent Delhi elections on the back of a campaign centred on corruption and basic services. Their manifesto describing water as "the biggest concern of the aam aadmi [common man] in Delhi" made it a key campaign issue. Their posters read: "A warning to power: no water, so no vote".

Despite accusations of being a middle-class party, AAP in fact attracted a lot of votes from Delhi's poorer neighbourhoods. For areas without good water access, water may be "arranged" by local leaders, usually aligned to the two main parties, in return for local support. Perceived withdrawal of loyalty may be met with threats, harassment or violence. By framing corruption around these issues of access to basic services, AAP has seemingly found a deep well of support. However, the day after AAP came into government, neighbourhoods in south Delhi found their water cut off, apparently a water mafia response to AAP's policy of free basic water. Kejriwal refused extra security and the AAP's efforts against illicit water continue.

Lack of adequate water and sanitation are significant impediments to social and economic development in India. Sickness from polluted water is frequent. Girls in unserviced areas often skip school waiting in line on "water day", or don't sleep as they wait for the water to come on in the night. Indian bathrooms, for those lucky enough to have them, are commonly fitted with two sets of taps. One is for municipal water that runs at very low pressure at sporadic intervals (perhaps a couple of hours twice a day in Delhi's better areas), if at all. The other set is for alternative water, supplied from groundwater pumped from below the building, or sumps filled by delivery tankers, also often using untreated groundwater.

As groundwater declines, and climate change kicks in, control over water is a source of power. In the land of khaadi kurta-clad politicians, Kejriwal has become famous for his signature combination of "old uncle" sweater, "borrowed watchman's" muffler and the Nehru hat that has become the party's symbol. But the AAP is not all spin. As a political party it grew out of the India Against Corruption movement, the country's Arab Spring, and is bringing an activist mentality into electoral politics. While this has sometimes spilled over into the ugly side of populism, the AAP has shown a shrewd ability to draw support from the urban middle class and poor alike.

After Kejriwal recently stepped down as Delhi chief minister, citing obstruction from the mainstream parties, the AAP started preparing for a national campaign. Fielding candidates from an impressive coalition of campaigners and social activists, including veteran environmentalist Medha Patkar, AAP has the potential to play spoiler or kingmaker in the upcoming elections.

If AAP is to succeed they need more than grassroots campaigning and popular discontent. Policies and schemes for water resource development in India have not recognised the political, social and economic roles of water outside of the official system. As a result, they have been bound to fail. The expensive, technology-heavy model of water supply that is often promoted mainly benefits international companies, consultants and local elites, destroying traditional, sustainable water practices in the process. AAP has made a promising start in tackling these problems in Delhi. They will need to continue to address these issues if they are to balance electoral populism with their promises of social justice. more