The pipes descended below and after travelling underground crossed into the Taj enclosure. One pipe line runs directly towards the mosque to supply the fountains in the tanks on the red sandstone plinth below the marble structure. Copper pipes were used for separate series of fountains in the north-south canal, lotus pond and the canal around it. An ingenious method was devised to ensure uniform and undiminished water pressure in the fountains, irrespective of the distance and the outflow of water. A copper pot was provided under each fountain pipe - which was thus connected to with the water supply only through the pot.
Water first fills the pot and then only rises simultaneously in the fountains.
The fountains are thus controlled by pressure in the pots and not pressure in the main pipe. As the pressure in the pots is uniformly distributed all the time, it ensures equal supply of water at the same rate in all the fountains. The main supply of the water was however obtained through earthenware pipes. One such main was discovered under the bed of the western canal. Evidently, the Mughal water expert was a master of his art and successfully worked out the levels in relation to the volume of water to ensure its unobstructed supply for centuries.