Infectious diseases with water-associated transmission pathways constitute a large burden of disease globally. Since the AR5, the evidence has strengthened that waterborne diseases, and especially gastrointestinal infections, are highly to moderately sensitive to weather variability . Increased temperature and high precipitation, with associated flooding events, have been shown to generally increase the risk of diarrhoeal diseases. There are, however, a number of studies that describe important exceptions and modifications to this general observation. While high temperatures favour bacterial diarrhoeal diseases, virally transmitted diarrhoea is on the contrary mostly associated with low temperatures . Socioeconomic determinants, such as the existence of single- household water supplies  or combined sewer overflows , have been shown to critically increase the risk of gastrointestinal infections linked to heavy rainfall in high- income countries. Also, for both low- and high-income countries it has been found that gastrointestinal diseases increase following a heavy rainfall event only if preceded by a dry period . Yet, so far there is no consistent evidence on the role of droughts in favouring waterborne disease transmission . As exemplified by the large cholera outbreak following the 2010 earthquake in Haiti, the existence of functioning sanitation systems is critical for preventing waterborne disease outbreaks, while climatic factors  are important in driving the transmission dynamics once the outbreak has started . Other socioeconomic factors, such as human mobility and water management projects , also modify the strength of the association between climatic factors and waterborne diseases, as shown by recent studies in Africa .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report