The European citizens' initiative (ECI) mechanism, introduced in 2012, enables one million citizens from at least one quarter of EU member states to call on the European Commission to act in fields within its competence.
Right2Water was the first successful ECI. Originating in Ireland, the campaign was launched amid fears that water services would be privatised.
Rapporteur Lynn Boylan's report was adopted with 363 votes in favour, 96 against and 261 abstentions.
The Irish MEP called this result "a victory for civil society and for Right2Water campaigners across Europe. The 1.8 million signatories of the initiative [in 13 member states] have finally received the support they deserve from an EU institution."
She said "the Commission's initial response to the ECI was vague, disappointing and did little to answer their demands. In this report fellow progressive MEPs and I have come together to produce a report which better answers their campaign."
"We have called on the Commission to produce legislative proposals which will enshrine the human right to water in EU legislation, avoiding the privatisation of water services and also to make sure that water services are excluded from the transatlantic trade and investment partnership (TTIP) negotiations."
The Commission had previously come under fire for its response to the Right2Water campaign, after it failed to respond to campaigners' request rule out the liberalisation of water services in the EU and in trade talks.
The Commission's official communication said, "the decision on how best to operate water services is firmly in the hands of the public authorities in the Member States".
The report urges the Commission to enshrine access to water as a human right in EU law and permanently exclude water services from internal market rules and trade negotiations. It met opposition from Parliament's centre-right European People's Party and European Conservatives and Reformists groups.
Group of the Progressive Alliance of Socialists and Democrats shadow rapporteur Iratxe García Pérez commented, "water is a public good, and we will always oppose any attempt to privatise it. It is hard to understand why the right-wing MEPs in Parliament try to undermine the citizens' initiative and weaken the demands for a fair and social use of access to water."
Greens/European Free Alliance deputy Claude Turmes underlined that, "the major popular mobilisation behind the initiative shows that this issue is a top priority for Europe's citizens and it behoves the EU institutions to respond positively to this appeal for action. Faced with ongoing threats to water services in Europe, the EU institutions should be defending citizens' basic rights as regards the provision of this fundamental service."