Background

The Secure Water Treatment (SWaT)™ Testbed was the first testbed built by iTrust, with funding from the Ministry of Defence (MINDEF) of Singapore, and under the guidance PUB, Singapore’s national water agency. It was commissioned on 18 March 2015 by Chief Defence Scientist Professor Quek Tong Boon. The SWaT testbed has since been a key asset in cyber security research and remains a cornerstone in iTrust operations. The testbed is a scaled-down, high-fidelity, industry-compliant emulation of a modern water treatment facility. The testbed consists of multiple physical and cyber components that combine to form a modern six-stage water treatment process. 

SWaT Architecture

The SWaT testbed, in its modern six-stage process configuration, comprises various electrical, electronic, physical, and mechanical components. It is operationally capable of water treatment and purification at a rate of 5 gallons of water per minute (GPM) or approximately 19 litres of water per minute (l/min).

SWaT Physical Layout

Physical Process

The SWaT Physical Process begins at Stage 1, where raw water is drawn into a storage tank. The water then proceeds to Stage 2 for pre-treatment, involving disinfection and pH balancing. Following this, it advances to Stage 3, where it passes through an Ultrafiltration (UF) unit to remove particles larger than 0.1µm such as solid matter and bacteria. In Stage 4, the water undergoes dechlorination through Ultraviolet (UV) lamps to remove free chlorine to prevent oxidation of the Reverse Osmosis (RO) membranes. In Stage 5, the water is directed into a Reverse Osmosis (RO) system resulting in two streams: the first being the RO permeate and the second being the RO reject, which are directed to 2 separate storage tanks in Stage 6. Stage 6 involves a backwash process, which uses the RO reject to clean the UF membranes.

The design and implementation of the SWaT testbed places great emphasis on sustainability, which is why the plant recycles its water either within a closed loop where the RO permeate becomes a source of water for the Raw Water stage or by transferring the RO permeate over to the WaDi testbed. This ability of the testbed is a deliberate design and implementation choice, given that water is a scarce and valuable resource in Singapore’s context.

Block Diagram of SWaT Physical Process

SWaT Physical Layout

Network Architecture

The SWaT Network Architecture, i.e., the cyber portion of SWaT, comprises dedicated OT hardware in Allen-Bradley Programmable Logic Controllers (PLCs), Schneider Remote Input/Output (RIO) units and a combination of IT software and hardware in the Human Machine Interfaces (HMIs), Supervisory Control and Data Acquisition (SCADA) workstation and Historian.

The SCADA supervises the SWaT process through periodical monitoring and has the ability to take manual control of the SWaT testbed by overriding the pre-existing PLC programming. The SCADA also works in conjunction with the Historian which serves the important role of recording and storing process data for subsequent analysis. The IT and OT components co-exist on a network that employs a layered communications network using the Purdue Model for Industrial Control Systems (ICS). The PLCs use the EtherNet/IP (ENIP) as the main communication protocol.

Notable aspects of the testbed include segmented communications networks, both wired and wireless communications, distributed dynamic control, interconnection among the testbeds, and complete access to the control logic within the PLCs and HMIs. The SWaT testbed employs the use of Wireless Access Points (WAP) to achieve wireless communications. This accessibility allows researchers to develop and upload their code in the controllers for research and experimentation. It also provides a platform for demonstrating their technologies in a safe, controlled, and realistic environment.

SWaT Network Architecture

See a video walkthrough of SWaT testbed here.