A utility can possess substantial production and treatment capacity while remaining exposed to changes outside its direct control. In Berlin, drinking water comes from groundwater and much of that source is connected to the regional surface-water system through bank filtration.
Published evidence states that about 70 per cent of drinking water is obtained through bank filtration. This operating model provides a natural treatment pathway, but it also links source reliability to aquifer recharge, river conditions and the quality of water moving through the wider cycle.
The current asset platform is large: nine waterworks and reported production capacity of 1.1 million cubic metres per day. Annual water sales were 217 million cubic metres in 2025. Capacity and sales answer different questions and cannot be used alone to infer spare dependable supply.
Resource conditions are tightening. Available reporting records repeated drought pressure since 2018, apart from 2021, and groundwater levels in some areas up to 75 centimetres below the long-term average. These observations make source condition an operating issue rather than a remote environmental concern.
A separate regional assessment warns that dry-summer River Spree flows could fall locally by as much as 75 per cent after the Lusatian coal phase-out. That is a regional scenario, not a utility performance result, but it matters because river and groundwater systems are connected.
Treatment investment therefore supports more than compliance. Where treated return flows have greater influence during low-flow periods, wastewater quality becomes part of the broader source-security equation. Water and wastewater decisions need to be assessed together.
Berliner Wasserbetriebe's response includes deeper wells, reactivated waterworks, treatment expansion and stronger monitoring. Each option has a different maturity, location and operating role. None should be counted as dependable capacity before the relevant evidence supports that state.
Urban stormwater management adds another connection. Local retention, infiltration and evaporation can reduce pressure on drainage systems while supporting a more resilient urban water cycle. Delivering those outcomes depends on streets, buildings, open space and planning decisions beyond utility property.
The Berlin Rainwater Agency and the Blue-Green Alliance provide institutional routes for this coordination. Their importance lies less in organisational labels than in the ability to connect utility operations with land, development and public-realm decisions.
A resilient strategy therefore needs a recurring resource balance joining demand, groundwater condition, river flow, treatment quality, asset availability and delivery status. Installed capacity remains important, but it cannot substitute for this system view.
The full report examines these dependencies from the utility's perspective, while the Berlin City and Berliner Wasserbetriebe DATA products retain the wider urban context and detailed supporting evidence.