Coagulation remains a technique by which finely dispersed solids are efficiently eliminated. It has been largely expanded and remains the most unavoidable method for treating water. This review focuses on colloid stability, coagulation mechanisms, and coagulant types. It presents electrocoagulation as an option of conventional coagulation and discusses challenges in coagulation technology especially health hazards in used chemicals toxicity. As promising solutions, new developments in terms of using coagulants are presented. Micropollutants are inorganic and organic substances that could disturb negatively nature even at very low levels. Microplastics are also observed. Coagulation could retain different micropollutants and microplastics at varying efficiencies even if there is a need to determine running circumstances that could increase their reduction. As a perspective, coagulation may be combined with additional processes, such as ultrafiltration. Further, traditional water treatment should be deeply revised.