## 1 Introduction  
The development of safe drinking water supplies relies on two key factors, namely, quantity and quality [1]. In European countries, the risk assessment associated with water consumption is based on monitoring programs for bodies of water that provide more than 100 m\({}^{3}\) a day on average [2]. In Romania, the quality of drinking water is surveyed through the national program for monitoring the environmental and occupational risk factors. An effective drinking water monitoring is highly required in order to reduce the impact of water pollution on human health, particularly on the development of cancer, gastrointestinal, and childhood diseases [3]. While water-borne diseases are well documented, such as diarrheal disease on which a published study estimated that 34% out of 58% of all cases of diarrhea was due to inadequate drinking water in low- and middle-income countries for the year 2012 [4], the health impact of water radioactivity and chemical contamination remains an issue of concern. It was found that cancer risks arise from disinfection by-products, arsenic, and alpha particle radiation [5]. Consistent evidence supports that arsenic level above a certain threshold in drinking water increases the risk for bladder cancer [4]. Heavy metals, pesticides, hydrocarbons, or persistent organic pollutants may cause reduced reproduction, abnormal behavior (mercury), and damages to the nervous system, liver, and kidneys [6]. Recently, lithium concentration in tap water has become a debatable issue since maternal prenatal exposure to natural water sources in Denmark was associated with autism risk in the offspring, as lithium levels increased [7]. On the other hand, the presence of lithium at very low concentrations was associated with reduced suicide rates, and water supplementation with lithium was proposed for discussion as a public policy [8]. The sources of chemical hazards that are of health significance in drinking water are as follows: naturally occurring (source of Ba, B, As, Cd, F, and uranium in the final water), industrial and human dwellings (source of Cd, Hg, benzene, styrene, toluene, carbon tetrachloride, nitrilotriacetic acid, and 1,4-dioxane in the final water), agricultural activities (source of nitrates, nitrites, and pesticides in the final water), water treatment or materials in contact with drinking water (source of disinfectants such as chlorine, monochloramine, and sodium dichloroisocyanurate, and of piping materials such as Cu, Pb, Ni, and vinyl chloride in the final water), and pesticides used in water for public health--vector control (source of DDT and larvicide) [9]. Radioactive substances (radionuclides) occur naturally (e.g., the decay series of uranium and thorium) and artificially (e.g., Caesium-134, lodine-131, Tritium, or Strontium-90) and are not routinely monitored to detect potential exceeding of the screening level--the total radioactivity in the form of alpha and beta radiation. Drinking water sources from groundwater may also contain radon, which is a radioactive gas of a great health concern [10; 11]. Radon substantially contributes to the natural human exposure to radiation via inhalation and direct digestion, causing lung or stomach cancer [12]. Using advanced computing techniques, several models have been developed for the prediction of water quality components, and, recently, artificial intelligence (AI) techniques showed suitable performance in this field [13]. For detailed information on machine learning algorithms, readers are invited to refer to the study of [PERSON] et al. [14]. It is worth mentioning two of the predictive models using meaningful physical, chemical, and microbial indicators, namely, the Adaptive Frequency Analysis proposed to solve scalability in the time domain [15], and the LASSO (Least Absolute Shrinkage and Selection Operator) regression model proposed to predict the biological risk [16]. Moreover, computational intelligence techniques are developed and tested on a small scale, aiming to achieve smart water management systems [17].