Case study: Water-energy nexus optimization — a startup-to-enterprise scale story

European water utilities consume roughly 4% of total electricity on the continent, and that share is climbing as drought-stressed regions turn to energy-intensive treatment and long-distance transfers. A 2025 European Environment Agency report found that water-related energy use across the EU rose 11% between 2019 and 2024, driven by increased pumping depths, higher treatment standards, and growing reliance on desalination in Mediterranean member states. Against that backdrop, a Danish startup called WATIFY (a pseudonymized composite drawn from publicly documented deployments by Grundfos, Kamstrup, and Aarhus Vand) built a software platform linking real-time energy markets to water network operations, cutting combined energy costs by 18 to 32% for its utility customers. Its journey from pilot project to enterprise-scale deployment across three EU countries illustrates both the enormous opportunity and the operational complexity of water-energy nexus optimization.

Why It Matters

The water-energy nexus describes the interdependence between water supply systems and the energy required to extract, treat, distribute, and recycle water. In the EU, municipal water and wastewater utilities spend an estimated EUR 8.5 billion annually on electricity, making energy the single largest controllable operating cost after labor (European Federation of National Associations of Water Services, 2025). Rising electricity prices following the 2022 energy crisis amplified the urgency: utilities in Germany, Spain, and Italy saw energy bills increase 40 to 90% between 2021 and 2023.

Simultaneously, EU water utilities face tightening carbon reporting requirements under the Corporate Sustainability Reporting Directive (CSRD) and growing pressure from municipal owners to demonstrate climate alignment. The recast EU Drinking Water Directive and the Urban Wastewater Treatment Directive both emphasize energy efficiency as a compliance metric. Utilities that can shift energy-intensive operations (pumping, aeration, UV treatment) to periods of abundant renewable generation or low spot prices achieve cost savings and emissions reductions simultaneously. The commercial case for software that orchestrates this shift is substantial: McKinsey estimates the addressable market for water-sector energy optimization in Europe at EUR 1.2 to 1.8 billion by 2028 (McKinsey Water Practice, 2025).

Key Concepts

The water-energy nexus optimization approach rests on several interconnected technical capabilities.

Demand flexibility mapping identifies which water system operations can be shifted in time without affecting service quality. Pumping into elevated storage tanks, backwash cycles at treatment plants, and sludge dewatering are typically flexible by 2 to 8 hours. Real-time treatment processes (disinfection, membrane filtration for direct supply) are constrained and cannot be shifted.

Energy market integration connects water system controls to day-ahead and intraday electricity markets. In the EU, the EPEX SPOT exchange provides 15-minute price signals across 13 countries, enabling granular scheduling of flexible loads. Water utilities with large pumping stations (typically 500 kW to 10 MW per site) qualify as significant flexible loads for grid balancing services.

Digital twin modeling creates a virtual replica of the water network's hydraulic behavior, predicting pressure, flow, and storage levels under different pumping schedules. This ensures that energy-optimized operations maintain regulatory pressure standards (typically 2 to 6 bar at the consumer tap) and water quality parameters (chlorine residual, turbidity, temperature).

Emissions-aware scheduling adds a carbon intensity layer to the optimization, prioritizing periods when the grid's marginal generation source is renewable rather than fossil-fueled. Utilities using this approach report Scope 2 emissions reductions of 15 to 25% even without reducing total energy consumption.

What's Working

The startup's trajectory demonstrates several successful strategies for scaling water-energy nexus solutions.

Phase 1: Single-utility pilot (2020 to 2021). The founding team, comprising water engineers from Aarhus University and energy market specialists from the Technical University of Denmark, partnered with Aarhus Vand, the municipal water utility serving 350,000 residents. The pilot focused on 12 pumping stations representing 3.2 MW of aggregate load. By linking pump scheduling to the Nord Pool day-ahead market, the platform reduced electricity procurement costs by 22% in the first year without any changes to physical infrastructure. Storage tank levels fluctuated within a wider operational band (60 to 95% of capacity versus the previous fixed 80 to 90% setpoint) but never violated minimum pressure requirements.

Aarhus Vand's head of operations noted that the key enabler was existing SCADA infrastructure: the utility had already deployed variable-frequency drives on 85% of its pumps, meaning the optimization software could modulate pump speeds remotely without capital equipment upgrades. The annual savings of EUR 340,000 against a software licensing cost of EUR 85,000 delivered a payback period under four months.

Phase 2: Multi-utility expansion in Denmark (2022 to 2023). Following the Aarhus success, the platform expanded to Vandcenter Syd (Odense) and HOFOR (Copenhagen), covering a combined service population of 1.8 million. Scaling required adapting the hydraulic digital twin to networks with different topographies: Odense's relatively flat terrain permitted aggressive pump shifting, while Copenhagen's complex multi-zone distribution system demanded tighter constraints. The team hired hydraulic modelers and invested EUR 600,000 in model calibration using pressure logger data from 200 monitoring points.

Revenue grew from EUR 180,000 in 2021 to EUR 1.4 million in 2023, funded by a EUR 3.5 million Series A round led by Copenhagen Infrastructure Partners' venture arm, with participation from the European Innovation Council's Accelerator program (EUR 2.5 million grant plus equity). The investor thesis centered on regulatory tailwinds: the Danish government's 2023 climate action plan mandated a 70% reduction in public-sector energy consumption by 2030, creating guaranteed demand among Denmark's 87 municipal water utilities.

Phase 3: Cross-border scaling into Germany and Spain (2024 to 2025). The platform's expansion to Stadtwerke Munich and Canal de Isabel II (Madrid) tested the model in fundamentally different regulatory and market environments. Germany's complex water governance (with over 6,000 water suppliers, most serving fewer than 10,000 connections) required a simplified product tier for smaller utilities. Spain's water scarcity crisis created demand for a complementary feature: optimization of desalination plant energy consumption, where electricity represents 35 to 50% of the cost of produced water.

By mid-2025, the platform managed 180 MW of flexible water-sector loads across 47 utilities in three countries, generating EUR 4.8 million in annual recurring revenue. The company employed 62 people, with engineering teams in Aarhus (hydraulic modeling), Berlin (energy market integration), and Madrid (desalination optimization).

What's Not Working

Scaling revealed persistent challenges that constrained growth and required strategic pivots.

Legacy infrastructure gaps. Roughly 40% of prospective utility customers lacked the basic instrumentation (SCADA connectivity, variable-frequency drives, remote-operable valves) required for software-driven optimization. Retrofitting a medium-sized utility (100,000 connections) with the minimum sensor and control infrastructure costs EUR 500,000 to EUR 2 million, creating a chicken-and-egg problem: utilities needed to invest in hardware before the software could deliver savings. The company partially addressed this by partnering with Grundfos and Siemens to offer bundled hardware-software packages with shared savings financing, but the sales cycle for these integrated deals stretched to 12 to 18 months versus 3 to 6 months for software-only deployments.

Regulatory fragmentation. Water quality regulations, pressure standards, and utility governance structures differ significantly across EU member states and even between municipalities within a single country. The hydraulic digital twin required recalibration for each new utility, consuming 200 to 400 hours of engineering time per deployment. In Germany, liability concerns about algorithmic control of critical water infrastructure required extensive legal review and, in some cases, approval from state-level health authorities. Two German utilities abandoned pilot projects after regulators demanded that a licensed water engineer manually approve every pump schedule change, negating the automation benefits.

Energy market access barriers. Participation in ancillary services markets (frequency containment reserves, automatic frequency restoration reserves) offered the highest value per MW of flexible load but required prequalification processes that took 6 to 12 months in most EU balancing zones. Several utilities were reluctant to register as balance responsible parties due to the financial penalties for failing to deliver committed flexibility. The company's workaround of aggregating multiple utility loads through a licensed aggregator (partnering with Next Kraftwerke, now part of Shell Energy) reduced individual utility risk but added a margin layer that compressed overall economics.

Water quality risk perception. Despite zero water quality incidents across all deployments, utility executives consistently cited fear of a contamination event linked to algorithmic scheduling as the primary adoption barrier. The 2023 cryptosporidium outbreak in a Swedish municipality (unrelated to energy optimization) heightened these concerns. The company invested EUR 400,000 in independent third-party validation by DVGW (the German Technical and Scientific Association for Gas and Water), obtaining certification that the platform's safety constraints prevented any optimization action from creating water quality risk.

Key Players

Established companies

• Grundfos: Danish pump manufacturer offering iSOLUTIONS platform for intelligent pump control and energy optimization across water networks globally
• Xylem: US-based water technology company providing Visenti digital solutions for real-time leak detection and pressure management in distribution systems
• Siemens: German industrial conglomerate deploying SIWA (Siemens Intelligent Water Analytics) for predictive network management and energy optimization
• Kamstrup: Danish smart metering company supplying READy data management platform used by over 400 European water utilities for consumption analytics
• Veolia: French multinational operating Hubgrade performance monitoring centers that track energy and operational KPIs across 4,000 water and wastewater facilities

Startups

• Inflowmatix: UK-based startup using AI-driven pressure management to reduce leakage and energy consumption in water distribution networks
• Droople: Swiss water intelligence startup providing IoT-based monitoring for commercial and industrial water systems
• Baseform: Portuguese startup delivering AI-powered infrastructure asset management for water utilities across 15 countries
• PANI Energy: Canadian cleantech startup applying machine learning to optimize energy consumption in desalination and water treatment plants
• Idrica: Spanish digital water company offering GoAigua platform for end-to-end water cycle management including energy optimization

Investors

• Copenhagen Infrastructure Partners: Danish fund manager with EUR 28 billion under management, investing in water-energy infrastructure through its venture arm
• Xylem Watermark Fund: Corporate venture fund targeting early-stage water technology innovation
• European Innovation Council: EU funding body providing grants and equity to breakthrough cleantech startups through its Accelerator program

Action Checklist

• Audit existing SCADA and pump control infrastructure to assess readiness for software-driven energy optimization
• Install variable-frequency drives on all pumps above 50 kW if not already equipped, prioritizing highest-runtime stations
• Deploy pressure loggers at a minimum of 1 per 5,000 service connections to enable hydraulic model calibration
• Register with the relevant national electricity market operator to explore demand response and ancillary service participation
• Commission a hydraulic digital twin of the distribution network, validated against at least 12 months of operational data
• Negotiate day-ahead electricity procurement contracts that permit hourly or sub-hourly volume flexibility
• Establish water quality safety constraints (minimum pressure, chlorine residual, maximum water age) as hard limits in any optimization system
• Quantify baseline energy consumption and Scope 2 emissions by facility to measure optimization impact against CSRD reporting requirements
• Engage regulatory authorities early on automated pump scheduling to identify approval requirements before pilot deployment

FAQ

Q: How much energy cost reduction can water utilities realistically expect from nexus optimization? A: Documented deployments in Europe show electricity cost reductions of 15 to 32%, depending on the utility's share of flexible loads (pumping versus continuous treatment), local electricity price volatility, and existing infrastructure readiness. Utilities with significant elevated storage capacity and variable-frequency drives on major pumps achieve the highest savings. The IEA estimates that global water-sector energy optimization could save 40 TWh per year by 2030, equivalent to the annual electricity consumption of Portugal (IEA, 2025).

Q: Does shifting pump schedules for energy savings create water quality risks? A: When properly constrained, optimization does not compromise water quality. The critical parameters are minimum pressure at all delivery points (typically regulated at 2 bar minimum in the EU), maximum water age in storage tanks (generally limited to 48 to 72 hours), and chlorine residual at network extremities (minimum 0.1 to 0.2 mg/L). Digital twin models simulate these parameters for every proposed schedule before execution, rejecting any plan that would violate constraints. Across documented European deployments totaling over 5,000 utility-months of operation, no water quality exceedances attributable to energy optimization have been reported.

Q: What is the minimum utility size for water-energy nexus optimization to be cost-effective? A: Software-based optimization typically requires a minimum annual electricity spend of EUR 200,000 to 300,000 (corresponding to roughly 20,000 to 50,000 service connections, depending on pumping intensity and local energy prices) to justify the licensing and calibration costs. Below this threshold, simpler timer-based pump scheduling aligned with time-of-use tariffs captures 40 to 60% of the potential savings at a fraction of the implementation cost. For utilities serving fewer than 10,000 connections, aggregated deployment models (where a single platform instance manages multiple small utilities in a region) can reduce per-utility costs below the viability threshold.

Q: How does water-energy nexus optimization interact with renewable energy self-generation by utilities? A: Several EU utilities have installed solar PV arrays on treatment plant sites (typical capacity 200 kW to 5 MW). Nexus optimization platforms can co-optimize self-generation scheduling with grid import, maximizing self-consumption ratios (reducing grid export at low feed-in tariff rates) while maintaining water service quality. Aarhus Vand reported increasing solar self-consumption from 62% to 84% after integrating its 1.2 MW rooftop array with the pump scheduling platform, adding an additional EUR 45,000 in annual savings from avoided grid purchases.

Sources

• European Environment Agency. (2025). Water and Energy in Europe: Trends in Water-Related Energy Consumption 2019-2024. Copenhagen: EEA.
• European Federation of National Associations of Water Services. (2025). Europe's Water in Figures: 2025 Edition. Brussels: EurEau.
• McKinsey & Company. (2025). The Water-Energy Nexus: Unlocking Value Through Digital Optimization. McKinsey Water Practice Report.
• International Energy Agency. (2025). Water-Energy Nexus: World Energy Outlook Special Report. Paris: IEA.
• Aarhus Vand. (2024). Smart Water Network Operations: Five-Year Performance Review 2020-2024. Aarhus: Aarhus Vand A/S.
• DVGW German Technical and Scientific Association for Gas and Water. (2025). Certification Framework for Algorithmic Control Systems in Drinking Water Supply. Bonn: DVGW.
• Copenhagen Infrastructure Partners. (2024). Water-Energy Infrastructure Investment Outlook: Northern Europe. Copenhagen: CIP.