The alarming growth of informal settlements in Tanzania is bringing with it multifaceted impacts. Health problems are the most felt among others. The study aimed at establishing how residences in informal settlement access sanitation and water service, and the prevalence of water borne diseases due to informal settlement and the public health consequences of this. The study employed both qualitative and quantitative approaches informed by case study design in which Tandale ward from Dar es Salaam Region were used. The study administered closed and open ended questionnaires were administered whereas interview was employed to the selected key informants. The study found that residents do not access clean water and sanitation in which poverty were attested to a major cause for the problem. Also, disposal and collection of wastes is seldom undertaken due to high cost of the service. Moreover, households lack permanent areas for the collection of wastes materials due to overpopulation. It was found that Tandale is worst hit with diseases caused by unsanitary environment and poor water provision. Respondents mentioned diseases like diarrhea, cholera, worms, malaria, schistomiasis and typhoid that have even led to incidences of death especially among children under 5 years. The study concluded that health problems affecting people living in informal settlements are real and that people are really suffering. However, such situation can be averted if the government works together with all stakeholders to get rid of the problem.