Because the Earthly life is the only type of life known to the mankind, it is logical to expect life-harboring planets to show similar characteristics as those of Earth. For instance, a habitable planet is expected to be rocky, and similar to Earth, to have formed through the collision of (rocky) protoplanetary bodies. As in our solar system, water is expected to have been delivered to the accretion zone of such an object by hydrated planetesimals and planetary embryos from regions beyond its orbit. Because in our solar system, Jupiter and Saturn formed much earlier than Earth, the above scenario has raised the question of whether giant planets are necessary for the delivery of water. By extension, some researcher have argued that the detection of a habitable extrasolar planet would be an indication of the existence of farther planetary bodies in their systems. To address this question, we have carried out a large number of simulations of terrestrial planet formation where we have studied the influence of the existence and absence of giant planets on the water content of the final bodies. Results demonstrate that while giant planets may affect the inventory of water-carrying objects, they play no role in the mechanics of the transfer and transport of water to rocky planets. Our simulations confirm that water delivery is in fact due to the mutual interactions of planetary embryos, a process that occurs even when no giant planet exists. We will present the results of our study and discuss their applications to extrasolar habitable planets.