*4.2. Cyber Wellness*

The scale IoT devices are growing even faster than the world's population. There will be 20.4 billion connected devices by 2020, compared with 7.8 billion global population [95]. These numbers highlight IoT's significance in the fourth industrial revolution, also known as the digital economy, where IoT is expected to deliver the "smarts" needed to address common everyday challenges in areas such as education, healthcare, utilities, transportation, and public and residential buildings [96].

SWS has a number of logical sub-layers in the integration of physical components and IoT, where sensors and actuators are deployed across the water distribution network to enable significant data processes and real-time performance. However, the pursuit of smartness without considering data authenticity and reliability would lead to information security issues. Many information safety issues are from system integration [42]. Thus, security at both IoT and network-level is critical to the operation of SWS [61]. Compared with physical network level components, these data-related smart sensors and intelligent devices with larger importance are the heart of SWS, occupying the decision-making resources. In comparison with the physical network level, the related data are easier to be chosen as the hitting points and even more vulnerable to cyberattacks because the hackers or cyberattackers might tend to crush the critical components of SWS or to steal the most crucial data saved in the database.

In this paper, we propose cyber wellness as one of the metrics to evaluate the information security of SWS. Cyber wellness is first put forward in the International Telecommunication Union (ITU) to describe the health level of information and communication technologies [97]. Continuously, cyber wellness is also introduced into the education field to describe the health level of Internet users [88]. In terms of information security, the emphasis from all cases is on how many of the IoT works well to extract data and how long it will last to defend itself when a cyberattack happens. In this work, we define the well-being level of information as "cyber wellness" in SWS. The goal of cyber wellness is, therefore, to store data as much as possible before a cyberattack and to withstand cyberattacks as long as possible at the same time shown in Equation (2):

$$\text{Cyber wellness} = \max(\text{Information security}, \text{capacity}, \text{educance}) \tag{2}$$

Cyber wellness is unitless, usually ranging from 0% to 100%. The higher cyber wellness reflects that the smart water system has more capacity to be against system failure and to prevent information loss.

#### **5. Future Research Recommendations**

A few challenges in the application of SWS are still waiting to be solved before the wide application of a smart water system [47]. More coordination is needed for collective work from the academia, industry, and government to enable smart techniques for public adoption. Based on the results of

this review paper and the work from different water organizations, several research directions are recommended to help engineers, researchers, and the public to work on those challenges in a more efficient and focused way.
