The new Article 70a of the Constitution states that that everyone has the right to drinking water and that water resources are a public good managed by the state and intended primarily to secure a sustainable supply of drinking water for the population.

The supply of drinking water to households is secured by the state through local communities directly as a non-profit service, the amendment states.

The tenth amendment to the Constitution was pushed through by left and centre-left parties with the argument that it will shield the crucial resource from excessive exploitation as water becomes scarcer due to climate change.

The lead sponsor of the motion, Alliance MP Alenka Bratušek, a former prime minister, said "we're doing the right thing for the future.

"We have been facing hot spots due to oil, in the future it will be about water," said Simon Zajc of the ruling Modern Centre Party (SMC), which co-sponsored the motion.

"Being able to drink tap water around Slovenia should not be taken for granted. It is a huge privilege that we must preserve for us and for generations after us," said Prime Minister Miro Cerar.

The opposition United Left (ZL), another co-sponsor, meanwhile defended the amendment with the argument that water will be protected from multinationals.

"Capital is hungry and thirsty, it can never get enough," said MP Violeta Tomić.

While the amendment was confirmed in a cross-partisan vote with 64 in favour and not a single vote against, the centre-right Democrats (SDS) and New Slovenia (NSi) expressed reservations and abstained.

SDS deputy Branko Grims accused the government of using the motion as a PR manoeuvre given that water was already sufficiently protected.

"This is nothing but PR, a show for the public...What is being adopted is already in the Constitution anyway," he said.

NSi president Ljudmila Novak argued that the state was not necessarily the best custodian, as evident from its failure to beef up flood defences.

The amendment is the result of several years of debate involving legal experts, the civil society and the parliamentary Constitution Commission.

By law it must be promulgated within eight days, whereupon changes to several laws will be required before it can be fully implemented.

The amendment has been welcomed by non-governmental organisations including Amnesty International Slovenije.

Amnesty suggested this now meant Roma living in illegal settlements, some of which have neither electricity or running water, are entitled to access to drinking water as well.

"Recognising access to drinking water as a constitutional right is an important step for Slovenia, but now we need concrete measures so that everyone can enjoy this fundamental right without discrimination," the organisation said.

Brane Golubović, a member of a civil initiative who pushed for the amendment when he was an MP, said the amendment was a historical act that would prevent water privatisation.

But he said it was merely the first step, noting that laws now needed to be amended in line with the spirit of the amendment.