The use of untreated domestic ...

The use of untreated domestic wastewater in agriculture may give rise to health risks, specifically to farmers and land labourers handling such water. As long as they do not swallow the water, main related risk concerns skin irritation. Health risks for consumers is of a different nature. First of all, contamination of crops is restricted to the water at the outside of the crop, and only applies to crops that are consumed raw. It is important to realise that the wetting of the crop not only takes place with irrigation in the field, but also at the market. Yet, health risks can be minimised and even stopped if the product is washed with clean water before consumption. It would be an excellent idea to provide irrigation and markets with fresh water only, to stop contamination at the outset. However, to apply full treatment to all polluted water streams in India would require enormous investments and management, an utopia for many years to come. Realising the volumes of water required for irrigation (easily 5000 m3/hectare per season) and treatment cost per m3 of water, it becomes evident that costs are a limiting factor. In this reality, it is a challenge for scientists and policy makers to improve the present situation at lower or none costs. Options to be worked out would include: - Avoid toxic elements (from industry) to mix with the domestic wastewater flows. - Before deciding on treatment, study the downstream use of the water flow. In case the effluent is used for irrigation, no nutritional elements (N, P, K) should be removed, as these are useful elements in agriculture. - If polluted water is used for irrigation, be restrictive in crop choice and use the most appropriate irrigation technique and proper irrigation water management. - Avoid (additional) contamination on the market and food chain. - Cleanse freshly eaten vegetables before consumption. Much more can be said around these subjects and increasingly more literature is available in support. Major lesson is that India should develop its own strategy and should not copy western technologies and approaches, as they have proven to be expensive. The Indian Water Week gives an excellent opportunity to further discuss such issues in interested groups.