ANIL LAUL , principal architect, Anangpur Building Centre, is best known for his advocacy of alternative technologies and building products. His projects have received many awards, and are listed as United Nations Centre on Human Settlements' good practices. Laul speaks to SHRADDHA NAVALLI about sustainable human settlement design and the role of environment-conscious building technologies.

But the drainage and sanitation systems in a city are closely linked, aren't they? 
Even with the existing sanitation system, we make a mistake at the very beginning. The first step is to separate kitchen and bath wastewater from the water closet (wc) discharge. Our kitchen and bath wastewater typically contains food residue, grease, dirt and soap as the main impurities. At present, they are sent via long pipelines to sewage treatment plants, which is unnecessary. This effluent can be locally discharged into broad-leafed plantations, such as banana and papaya trees, which are excellent digesters of grease. Grease, in fact, works as a nutrient for these trees! The remaining water percolates and recharges the groundwater. Another solution can be to utilise the brick-lined stormwater drains, which at present are used only for the two monsoon months in a year. Soil is a giant filter; its depth and size obviously make it a very efficient filter!

So planners haven't really understood the hydrological cycle (water in relation to the natural terrain) in cities? 
There is ample water to meet our needs, so long as we understand the hydrological cycle, and learn to utilise it effectively. Planning is all about small details that should be established at the local level.

For example? 
Take precipitation.