This tank is called Sivaganga and is the main and renowned sacred water. Here Lord Indira is said to have got the golden lotus for worshipping the god. The renown of the divine and ethical book of Thirukkural was established here by the appearance of a Sanga Palagai. (Platform for of approval of the script). Among the 64 Thiruvilaiyadals of lord Shiva the poet Nakkeerar is said to have argued against the god in this place.
Around the tank the stories of the Thiruvilaiyadals are depicted in the walls. Also in the Southern wall all the 1330 stanzas of the Thirukkural have been engraved on the white marble stones. Standing from the east of the tank one can see the golden Kalasas (pot like structure on the top of the tower) of the Swamy & Amman Sannidhis.
The golden lotus installed in this tank by the head of Thiruppananthal Mutt. It is a surprise that fishes or other creatures in water are not available in the tank. In the pillars on the northern side, the statues of 24 Sanga Poets and the statue of the merchant Dhananjayan who found the temple & also that of the Pandia King Kulasekar who constructed the temple and the town are seen.