Whether grown in small gardens or larger fields, using traditional or high-tech practices, horticultural crops have high water requirements. The quality of water used in horticulture is also critical, since water-borne pathogens on crops eaten uncooked can cause diseases such as typhoid and cholera. As cities grow, so does their demand for water, both for drinking and for use in urban economic activities, including horticulture. Over the past 20 years, access to water has improved and demand increased in many cities and slums. As a result, water resources have become increasingly scarce in the urban environment. Furthermore, inadequate wastewater management has led to progressive degradation of the quality of surrounding water courses and aquifers