The name of Calamba, according to legend, came from Kalan(clay stove) and Banga (water jar). I learned about this through the leaflets given during the 1st cityhood anniversary of Calamba.
Here it is:
During the Spanish period, two guardia civil (soldiers) were lost. As they walked around the place, they met a young lady who was carrying a jar of water and a wooden stove. In order to conceal the fact that they were lost, the soldiers asked her the name of the place using the Spanish language . The maiden, who do not understand Spanish, thought she was being asked on what she was carrying. She answered kalan-banga. It was believed that because the Spaniards could not pronounce kalan-banga properly, the town was then called Calamba.
To remind Calambeños of it's history, or should I say, of Calamba's etymology, a life-size replica of clay jar made of cement is in the city plaza and is called Banga. A fully-furnished Banga was finished in 1939. The banga is placed on top of a concrete mound. Inside the mound is a small, white fountain at the center and benches around. The semi-spiral stair beside the mound leads to the banga. 
You will notice that 1939 inscription seems to be written on a white cloth. It is a common practice to put a cloth on one's head, as protection, before placing a pot or whatever one intends to carry on his head.
Inscribed in the giant jar are the names of the different barangays comprising Calamba. I am a resident of Brgy. Mayapa, and I was frustrated when my BIG bro was unable to clearly and fully capture its inscribed name on Banga.
Banga(and the city plaza) is situated across Rizal shrine and St. John the Baptist church. You may view this for more information.
