The Jal Mandir meaning Water Temple, also known as Apapuri, in Pawapuri, meaning a town without sins, in the Indian state of Bihar, is a highly revered temple dedicated to Lord Mahavira, the 24th Thirthankara and founder of the Jain religion, which marks the place of his cremation. Mahavira attained Nirvana in Pawapuri in 528 BC.The temple has been built within a tank filled with red coloured lotus flowers. It is said that the temple was built by King Nandivardhan, Mahavira's elder brother. It is one of the five main temples in Pawpuri, where the "Charan Paduka" or foot impression of Mahavira is deified.
Mahavira was a prince of the Magadha Kingdom then known as "Madyama Pawa” or “Apawapuri", Like Buddha, he also became acetic at the age of 30. During one of the religious observances, called the chaturmas observed by Jains for four months during the rainy season starting from the beginning of the Hindu calendar month of Asarh and ending in the Hindu month of Kartik, the Jain monks and nuns remain at one holy place and preach the religious teachings of Jainism to the local people. Mahavira also observed this practice and during this period his one such stay was at Pawapuri. On the Diwali night on the 15th day of the month of Kartik, he breathed his last when he was 72 years old. While the place of his death is commemorated by a temple called the "Gaon Mandir" meaning "village temple" , the location where he was cremated, the temple built within a tank is known as the Jal Mandir. There is also another temple here dedicated to Mahavira called "Samosharan" where a statue of Mahavira delivering his last sermon is deified; the temple is circular in shape with beehive shape design
According to a local legend after Lord Mahavira attained Nirvana at Pavapuri he was cremated in the village. The place of his cremation became a pilgrimage centre when a large number of pilgrims took out a very large amount of soil from the site, which was considered as sacred ashes of Lord Mahavira, and thus created a huge pit which got filled up with water and became a tank. To commemorate the place of his cremation a temple was built within the tank.