SCADA Systems in Wastewater: Legacy Meets Modern

Nearly every wastewater utility in the US runs some form of SCADA (Supervisory Control and Data Acquisition) system. These industrial control platforms monitor pump stations, treatment plants, and collection system assets — and many of them are 15-25+ years old.

As smart sewer technology demands more sensors, faster data, and cloud connectivity, utilities face a critical question: modernize the existing SCADA, replace it entirely, or build around it?

What SCADA Does in Wastewater

A traditional wastewater SCADA system handles:

• Pump station monitoring — Wet well levels, pump status, run times, alarms
• Treatment plant control — Process variables, chemical dosing, aeration, disinfection
• Flow monitoring — Influent/effluent measurement at key points
• Alarm management — High levels, equipment failures, power outages
• Historical data logging — Trend data for regulatory reporting and analysis
• Operator interface (HMI) — Screens showing system status and allowing manual control

The Gap: What Legacy SCADA Can't Do

Legacy SCADA systems were designed for a different era — one where monitoring meant a few dozen sensors at major facilities, not hundreds or thousands of IoT devices distributed across the collection system. The gaps include:

• Scalability — Adding hundreds of new sensor points can overwhelm legacy architectures
• Cloud connectivity — Most legacy systems are isolated on local networks for security
• Advanced analytics — SCADA handles trending and alarming, not AI/ML prediction
• Mobile access — Legacy HMIs are desktop applications, not mobile-friendly web apps
• API integration — Connecting to modern cloud platforms and third-party tools is difficult
• Cybersecurity — Older systems may lack modern security features and receive no updates

Modernization Approaches

Option 1: Overlay Architecture

The most common approach: keep the existing SCADA for what it does well (pump station and treatment plant control) and add a parallel IoT platform for the new collection system sensors.

• Pros: Lowest risk, fastest deployment, preserves operator familiarity
• Cons: Two systems to maintain, potential data silos, integration complexity
• Best for: Utilities with a functional SCADA that just need to add collection system monitoring

Option 2: SCADA Modernization

Upgrade the existing SCADA platform to a modern version that supports IoT device management, cloud connectivity, and API integration.

• Pros: Single unified platform, vendor support, modern security
• Cons: Expensive, disruptive during transition, vendor lock-in risk
• Best for: Utilities whose SCADA is at end-of-life and needs replacement anyway

Option 3: Cloud-First Platform

Deploy a modern cloud-based platform (like Idrica GoAigua or Innovyze) as the primary analytics layer, with SCADA feeding data into it.

• Pros: Modern UX, advanced analytics, mobile access, API-first design
• Cons: Requires reliable internet connectivity, data sovereignty concerns, ongoing SaaS costs
• Best for: Utilities prioritizing analytics and smart capabilities over traditional SCADA functions

Cybersecurity Considerations

Connecting SCADA systems to IoT devices and cloud platforms introduces cybersecurity risks that must be carefully managed:

• Network segmentation between IT (cloud/IoT) and OT (SCADA/control) networks
• One-way data diodes for SCADA-to-cloud data transfer
• Multi-factor authentication and role-based access control
• Regular security assessments and penetration testing
• Compliance with NIST and WaterISAC cybersecurity frameworks

Compare SCADA and control system products or explore the SCADA glossary entry.