Growing population, industrialization, agricultural practices and urbanization have increased the water demand and hence the quantity of wastewater (ww). Availability of drinking water, including different components of daily per capita demand in developing countries, is becoming a serious issue to manage.

In this paper, a concept of ecological sanitation has been discussed in details. Ecological sanitation (ecosan) is a system designed for making sanitation and agriculture complementary, as it aims at reuse of reclaimed nutrients to the soil, and conserve valuable water resources.

The quintessential example of large scale municipal wastewater reuse is the new Groundwater Replenishment (GWR) System in Orange County, CA. The system treats clarified secondary municipal wastewater effluent and, utilising microfiltration, reverse osmosis and advanced oxidation to produce 70mgd of reclaimed water.

The need of new approaches for wastewater management and environmental demands worldwide is challenging product manufacturers to develop advanced technology. Scientists, engineers and regulators are exploring innovative ways of testing new approaches and thinking about how to accomplish and manage decentralised wastewater treatment.

The biggest challenge facing humankind is to reconcile the impact of humans with the ability of our planet Earth to provide resources and absorb waste. This "crisis" presents a potentially pivotal opportunity for architects, who have a crucial role to play in addressing this challenge. Sustainable cities are the building blocks of a peaceful and sustainable world.