There are 12 Theerthams (holy water tanks) around the hillock, namely:

• 1. Indra Theertham
• 2. Sambu Theertham
• 3. Rudra Theertham - There is also a small temple named “Rudhrakoteswarar temple” dedicated to lord Shiva and a visit to this temple is said to be equivalent to performing penance with 1000 rudrakshas. Of the 16 theerthams, which surrounds the temple, rudra theertham can be found here.
• 4. Vashishta Theertham
• 5. Meygyana Theertham
• 6. Agasthiya Theertham
• 7. Markandeya Theertham or Sangu Theertham
• 8. Kaushika Theertham
• 9. Nandi Theertham - The Nandi once undertook penance on the Earth. Pleased, Siva appeared before him and told him to ask for a boon. The Nandi desired that the place and the tank be named after him and asked that those taking a dip in the tank and worshipping Vedagiriswarar be absolved of their sins. His prayer was granted and hence the place is also known as Nandipuram and the tank, Nandi Thirtham.
• 10. Varuna theertham
• 11. Agalikai Theertham
• 12. Pakshi Theertham.

Of the above 12 theethams, Sangu theertham is the most renowned holy tank. It is an extensive tank of 1,000 square yards area, with wide steps on all sides. It is believed that Saint Markandeya, came down here after visiting Benares. He wished to have a bath in the sacred tank and perform abhishekam to the Siva lingam here but he found no vessel to take the water. Just then a conch suddenly emerged from the tank, with a humming sound, and Markandeya performed the abhishekam. It is said that even now once in 12 years, a conch emerges from this water, which the temple authorities collect with all honours and preserve in the temple in an enclosed glass box with dates mentioned therein. It is astonishing that a conch gets formed in fresh water since the natural phenomenon of a birth of a conch can happen only in salt water.