Water fasting


Water fasting is a type of fasting in which the practitioner consumes only water. One may water fast for a variety of reasons, including medical and religious requirements.

Religious requirement

Jainism

maintain a strict water-only fast for 8 to 10 days, during the days of Paryushan.

Roman Catholicism

must engage in the eucharistic fast before receiving the Eucharist during the Mass. While no nutritional or caloric sustenance is permitted, practitioners may take medicine if required, and those whose health problems impede them from fasting are dispensed of the obligation.
Up until the reforms of the Second Vatican Council, this fast was required from the previous midnight, as it is in various Orthodox Churches. However, under Pope Paul VI, the obligatory fast was reduced to only one hour before receiving the Eucharist.
The Catholic Church has also promoted a Black Fast, in which in addition to water, bread is consumed. Typically, this form of fasting was only used by monks and other religious individuals who practice mortifications and asceticism, but all Catholics are invited to take part in it with the advice and consent of their spiritual director.