Germany is asking itself how one of the world’s richest countries managed to be taken by surprise by last week’s extreme weather events, as more details emerge of how early warnings about record rainfall and expected floods did not make their way to the communities most at risk.

In Erftstadt, south of Cologne, where a flooded gravel quarry swallowed up cars, houses and parts of a historic castle, residents who had installed the federal government’s weather warning app were advised on Wednesday to stay inside their house.

By Thursday, they were informed that a nearby dam was at risk of breaking, putting them in “extreme danger”.

Yet in the Ahrweiler district in the state of Rhineland-Palatinate, where at least 117 people died after torrents of rainwater collected in the surrounding Eifel mountains and then tore through several villages last Wednesday, the Nina warning app had not sent out a comparable warning, the German news agency DPA reported on Monday.

Even though the European Flood Awareness System (Efas) sent out specific warnings for the worst-hit German regions four days before the start of the downpour, the ensuing flash floods still appeared to have taken the majority of residents by surprise.

Prof Hannah Cloke, a hydrologist at the University of Reading who set up and advises Efas, told Politico the death toll was “a monumental failure of the system”.

The interior minister, Horst Seehofer, dismissed suggestions that federal officials had made mistakes and said warnings were passed to local authorities “who make decisions on disaster protection”.

The interior minister of the western state of North-Rhine Westphalia, Herbert Reul, where 47 people died, conceded that the early warning system had not worked as efficiently as it could have, but said he did not see any fundamental problems with the system.

A spokesperson for Reul’s ministry on Monday said it had passed on warnings to the local municipalities concerned.

The head of Germany’s federal office of civil protection and disaster assistance appeared to shift the blame to local authorities. “The warning infrastructure as such wasn’t our problem, but the question of how sensitive the public authorities and the population are in their response”, said the agency’s president, Armin Schuster.

Schuster told broadcaster Deutschlandfunk that digital warnings, such as through warning apps, text messages or emails, did not always reach all those at risk. Instead, he called for an investment programme to increase the number of flood-warning sirens in areas that could see more floods in the coming years.

The disaster assistance agency has been facing scrutiny since last year’s “nationwide emergency warning day”, the first test run of the country’s warning infrastructure since reunification in 1991. Slated to run for 20 minutes, the event on 10 September 2020 was meant to demonstrate the functionality of everything from sirens to push notifications on smartphones.

Instead, the warning day demonstrated the current system’s gaps, with many receiving push alerts with a delay or not at all, after the nationwide push overloaded the system.

Annalena Baerbock, the Green party’s candidate for chancellor at elections this September, told Der Spiegel that the appropriate response to the catastrophic floods was a “tripartite national effort of strength”, involving a more centralised disaster management system, readjusting the design of cities and rivers for the event of more extreme weather events, and increased efforts on climate protection.

“We need to reshape disaster management,” Baerbock said. “And the federal government needs to take more responsibility for it.”

As receding water levels laid bare the full extent of the damage in towns and villages in western Germany, residents feared they could be left without access to power and drinking water for months.

In Ahrweiler, about 30,000 are currently without power, drinking water and gas, after Wednesday’s flash floods broke up sewage systems, tore through a major gas pipeline and brought a purification plant to a standstill.

“It looks like the infrastructure is destroyed so badly that some places won’t have drinking water for weeks or months,” the mayor of the town of Altenahr, Cornelia Weigand, told the newspaper Bild.

“It is clear that our community will end up looking very different, because those buildings that defined the area for more than 50, 100 or 150 years will have to be torn down.”

Even water towers in parts of the area that were spared the worst of the floods had run dry and had to be refilled either through tank lorries or by reviving disused wells and setting up mobile water treatment units, local media reported on Monday.

Germany’s Red Cross has transported two 7,000-litre (1,500 gallon) and four 3,800-litre tanks of drinking water into the region.

The Koblenz-based energy provider EVM said it was still in the process of establishing exactly how many households in Ahrweiler were without gas, which is used to heat water and homes in the region, but that the damage to its supply system was “dramatic”.