I was told this during childhood, that this is how St.Thomas converted certain Hindu Brahmins to Christianity. Also on Wikipedia:
Historical legend records that when St. Thomas landed at Palayur, he witnessed the sight of Hindu Brahmins, after their ablutions in a local tank, offering prayers by chanting mantras (the Vedic tradition of India for spiritual transformation) hymns to god in the form of Argyam or Tharpanam (water held in the palms) of water to the Sun god, a practice also said to be followed in Harappan and Persian cultures. Amused by the sight of water being thrown up by the Brahmins, from the palms of their hands, which was falling back, he challenged the Brahmins stating that the water they were offering was not being accepted by the Sun god as it was falling back into the tank. He made a deal with them stating that his God would accept the offer of water if he threw it up in the same way as they did, but water would not fall back. If he proved this then his God was superior and the Brahmins would have to embrace Christianity. He performed this miracle (summoned the Holy Trinity, completed the sign of the Cross and threw water held in his palms up into the air, which remained still in the air at a height) and with this miracle he converted a number of Brahmins and Jews in Palayur to Christianity. Thereafter he baptised the converts in a nearby water tank.
Is there any evidence or similar documented text outside India which confirms this miracle?