Temple tanks are well

Water well

A water well is an excavation or structure created in the ground by digging, driving, boring or drilling to access groundwater in underground aquifers. The well water is drawn by an electric submersible pump, a trash pump, a vertical turbine pump, a handpump or a mechanical pump...

s or reservoir

Reservoir

A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...

s built as part of the temple complex in Indian temples. Bathing in the sacred waters of these tanks is thought to cure disease and maladies. It is possible that these are cultural remnants of structures such as the Great Bath of Mohenjo-daro

Mohenjo-daro

Mohenjo-daro is an archeological site situated in what is now the province of Sindh, Pakistan. Built around 2600 BC, it was one of the largest settlements of the ancient Indus Valley Civilization, and one of the world's earliest major urban settlements, existing at the same time as the...

, which was part of the Indus Valley Civilization

Indus Valley Civilization

The Indus Valley Civilization was a Bronze Age civilization that was located in the northwestern region of the Indian subcontinent, consisting of what is now mainly modern-day Pakistan and northwest India...

.

Tank design

Since ancient times, the design of water storage has been important in India's temple architecture, especially in western India where dry and monsoon seasons alternate. Temple tank design became an art form in itself. An example of the art of tank design is the large, geometically spectacular Stepped Tank at the Royal Center at the ruins of Vijayanagara

Vijayanagara

Vijayanagara is in Bellary District, northern Karnataka. It is the name of the now-ruined capital city "which was regarded as the second Rome" that surrounds modern-day Hampi, of the historic Vijayanagara empire which extended over the southern part of India....

, the capital of the Vijayanagara Empire, surrounding the modern town of Hampi

Hampi

Hampi is a village in northern Karnataka state, India. It is located within the ruins of Vijayanagara, the former capital of the Vijayanagara Empire. Predating the city of Vijayanagara, it continues to be an important religious centre, housing the Virupaksha Temple, as well as several other...

. It is lined with green diorite

Diorite

Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar , biotite, hornblende, and/or pyroxene. It may contain small amounts of quartz, microcline and olivine. Zircon, apatite, sphene, magnetite, ilmenite and sulfides occur as accessory...

 and has no drain. It was filled by aqueduct

Aqueduct

An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....

.

The tank known as a "Pushkarni" or a "Kalyani", also known as a kund in Hindi is used for ritual cleansing and during rites of consecration. The water in the tank is deemed to be sacred water from the Ganges River

Ganges River

The Ganges or Ganga, , is a trans-boundary river of India and Bangladesh. The river rises in the western Himalayas in the Indian state of Uttarakhand, and flows south and east through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. By discharge it...

.

Stepwell

In India, a stepwell

Stepwell

Stepwells, also called bawdi or baoli , or vaav are wells or ponds in which the water can be reached by descending a set of steps. They may be covered and protected, and are often of architectural significance...

 is a deep masonry well with steps going down to the water level in the well. It is called a vav in west India and a baoli in north India. Some were built by kings and were richly ornamented.
They often were built by nobility, some being for secular use from which anyone could obtain water.

Kalyani

Kalyani, also called pushkarni, are ancient Hindu

Hindu

Hindu refers to an identity associated with the philosophical, religious and cultural systems that are indigenous to the Indian subcontinent. As used in the Constitution of India, the word "Hindu" is also attributed to all persons professing any Indian religion...

 stepped bathing

Bathing

Bathing is the washing or cleansing of the body in a fluid, usually water or an aqueous solution. It may be practised for personal hygiene, religious ritual or therapeutic purposes or as a recreational activity....

 wells.

These wells were typically built near Hindu temple

Hindu temple

A Mandir, Devalayam, Devasthanam, or a Hindu temple is a place of worship for followers of Hinduism...

s to accommodate bathing and cleansing activities before prayer. They are also used for immersion of Ganesha

Ganesha

Ganesha , also spelled Ganesa or Ganesh, also known as Ganapati , Vinayaka , and Pillaiyar , is one of the deities best-known and most widely worshipped in the Hindu pantheon. His image is found throughout India and Nepal. Hindu sects worship him regardless of affiliations...

 idols during Ganesha Chaturthi.