Nirjala Ekadasi - 23 June'18
Nirjala Ekadashi falls in the month of Jyestha in the Shukla paksha (June), therefore it is also called "Jyeshtha Shukla Ekadashi" or "Bhimsani Ekadashi" (Bhim sen, the seond Pandav Brother, had observed this difficult fast). Amongst the 24 Ekadashi's observed throughout the year, the fast (Vrat) observed on Jyeshtha Shukla Ekadashi is considered to be the most beneficial, if one properly observes a fast on this day it is said to give the fruits of 24 Ekadashi observed throughout the year. Complete fast is observed on this day with even water not being taken. People observe strict fast and offer pooja to Lord Vishnu to ensure happiness, prosperity and forgiveness of transgressions and sins. On the preceding day that is on the 10th lunar day, Sandhya (evening prayer) is performed and only one meal is taken.
additional information : http://www.rudraksha-ratna.com/nirjala-ekadashi.html