Mahamaham is a Hindu Kumbh Mela festival celebrated every 12 years in a town called Kumbakonam in Tamil Nadu, India. Hindus consider taking a holy dip at the Mahamaham tank on the day of Mahamaham as sacred. The festival takes place at a particular time as determined by astrological position: during the full moon of the Tamil month of Maasi (February-March) when the conjunction of the moon with the lunar asterism (Magha Nakshatra) and when Jupiter is in the constellation of Leo. People wash their sins on the holy rivers like Ganges, Yamuna, Godavari River and Kaveri River. These rivers wanted to get rid of their sins and approached Lord Brahma. Lord Brahma advised these rivers if you meet together and take bath in Mahamaham, you could wash off all the sins.
This year Mahamaham happened on 22nd February 2016. Several million devotees took bath last two weeks in the temple tank. Instead of getting into crowd you have the option of ordering the holy water in a bottle delivered to your house through online for Rs.150 + shipping, thanks to Tamil Nadu Government. I ordered on 8th February and got the package delivered today. The prasadam pack contains Holy Ash (விபுதி), Kumkum (குங்குமம்) and Temple tank Holy Water (தீர்த்தம்). If you wish to get one, you can order before 29th February 2016.