The major source of water for the stone spouts was the raj kulo (Royal Canal) which started from the foothills on the Valley rim, and fed into ponds which stored and recharged water for the aquifers, which were themselves largely dependent on rainwater.
A single stone spout may have had a single or multiple sources of water. Many were fed by either an individual spring or a local aquifer. Some sunken spouts were fed by shallow aquifers using percolated surface water, others were located near or far from a source. A single aquifer might supply water to a single spout, or to multiple spouts serving a number of communities.
Water was channelled through burnt clay or wooden pipes to the stone spouts through passages so that the water could flow easily. Most of the stone spouts had a base platform to capture discharged water, and a drain it through the side which served to supply another stone spout downstream, or irrigate nearby farms, before finally flowing into a river. When the springs and other water sources went dry and the water level in shallow aquifers went down, the stone spouts also discharged less water or became dry.
In this way, a complex and heterogeneous system was gradually developed over the centuries that utilised water from different sources, channelled it, often over considerable distances, and discharged it eventually through the spout, acting as a tap, for use by local communities.
Centuries after they were built, water from these sources are still being used by households, hotels, restaurants, factories and tanker operators, for laundry, personal hygiene and cleaning vegetables. Residents fall back on the traditional systems when there is not enough available water from the government piped system. However, the water is not potable anymore.
It is late, but not too late, however, to recognise the potential value of these systems with their multiple water sources, complex distribution channels and stone spouts. With proper conservation, they continue to supply much needed water to people of the Kathmandu Valley, in addition to maintaining an important archaeological heritage and the rich cultural associations of these living monuments, particularly for the Newa people whose forebears built them.