## 1 Introduction  
### Background  
Municipal water treatment technologies encompass a wide range of techniques, which can be classified into \"plus approaches,\" which involve chemical additives, and \"minus approaches,\" which rely on physical or biological processes without added chemicals. [PERSON] et al. argued in favor of minus approaches with respect to chlorine addition due to their lower risk of forming disinfection byproducts (DBPs), a growing health concern in drinking water [1]. While chlorination is effective against acute waterborne infections, it can generate halogenated organic compounds linked to chronic health issues, including bladder cancer and miscarriages [2]. Reducing DBP formation while ensuring microbial safety often involves eliminating particulate and dissolved organic carbon from water. Strategies include biodegradation, oxidative treatment, adsorption, and membrane separation--allaimed at minimizing both chlorine and organic matter, the main DBP precursors. The Netherlands has long employed this approach, achieving microbiologically safe water without chlorine by eliminating heterotrophic nutrients. Although the US regulations require chlorine residuals in treated water, focusing on organic precursor removal remains a viable strategy for DBP mitigation [3; 4; 5; 6; 7; 8]. Drinking water treatment for human consumption must address a wide range of contaminants that pose risks to human health. These include biological contaminants such as bacteria, viruses, and protozoa; chemical contaminants like arsenic, nitrates, and specific organic contaminants; and physical impurities such as turbidity and suspended solids. Contamination can arise from both natural sources--including geogenic arsenic in groundwater or volcanic activity--and anthropogenic activities, such as agricultural runoff, industrial discharge, and insufficient sanitation infrastructure [9; 10]. In rural and underserved communities globally, these challenges are often compounded by limited infrastructure, intermittent electricity, and low technical capacity. Consequently, treatment solutions in such contexts often rely on decentralized, low-cost, and easy-to-maintain technologies--such as biosand filtration or point-of-use chemical disinfection--to provide safe drinking water [11; 12]. A widely used method to ensure microbiological safety in drinking water is chlorination, valued for its cost-effectiveness and the ability to maintain a disinfectant residual throughout distribution systems. However, its effectiveness is heavily influenced by the presence of other contaminants in the water, which can interfere with microbial inactivation and react with chlorine to form harmful DBPs. To address this, the World Health Organization (WHO) only recommends chlorination at a maximum turbidity of 5 neph-elometric turbidity units (NTUs), with an operational target of \(\leq\)1 NTU to ensure reliable disinfection performance [13]. Similarly, the US Environmental Protection Agency (EPA) imposes specific turbidity and chlorine residual requirements under the Surface Water Treatment Rules. For systems using conventional or direct filtration, the EPA mandates that turbidity must never exceed 1 NTU, and that 95% of samples each month must be below 0.3 NTU, and _E. coli_ needs to be \(<\)1 MPN/100 mL [4]. For chlorination, the EPA requires a minimum free chlorine residual of 0.2 mg/L at the entry point to the distribution system and a detectable residual throughout the system to maintain microbial protection [14]. These standards reflect the critical importance of clarity and chemical stability for effective disinfection and public health protection. In low-resource settings, consistently achieving these targets remains a technical challenge, emphasizing the need for context-appropriate designs that integrate effective pretreatment (e.g., coagulation, sedimentation, and filtration) with disinfection. In industrial contexts, water treatment approaches differ widely depending on the specific application.