Question is really articulated well , in tune with,  what is happening now a days , with regard to water -related issues...I think , besides water quality , faulty management of irrigation water has played more negative role in economic growth than water quality alone...

Dear Yuni Rosadi,

In my opinion a response to your question refers to the viewpoint of the problem setting. Indeed, the water quality is an absolute necessity in the majority of experimental and laboratory contexts, whereas such a water purification is not actually an utmost importance factor in irrigation and agricultural services. In an economics viewpoint, another contentious issue is the volume of water treatment needed. Indeed, in a water supply network for urban areas water purification is an imperative need of apparently positive impact in the public health, while rainwater of poor quality enriches significantly the underground aquifers and contribute to sustainable irrigation water management when environmental concerns have to be also taken into account.

Dear Mr. Yuni,

It is absolutely correct that the quality of water is as important as the quantity of water available in determining the economic condition and growth. With the water quality deterioration, the production cost will increase because of expenses towards water purification; health index will come down due to consumption of bad quality water (direct or indirect), there can be products produced of sub-standard quality if the bad water quality water is used in agriculture or industries which in turn can create havoc in the society; etc. Considering all these it can be concluded that there is direct correlation between water quality and economic growth.

For sure, water quality positively correlates with life quality. However, if we focus only on GDP, in some cases regressions can give such results. Compare 2 countries A and B. Let A invests a lot in water purification, but since water is a free good, this investment does not contribute to GDP growth (but it definitely influences life expectancy, quality, etc). A country B may invest in something else and grow faster than A, but there will be long run negative effects on health. I think that China has focused mostly on growth last years and underestimated deteriorated ecology.

Pienso que todo depende del contexto analizado. En países como el mío (Bolivia), es posible encontrar que las mejoras en la calidad del medio ambiente, son percibidas como costos que hacen que muchas empresas dejen de ser competitivas, dado que los costos de producción se elevan, al considerar aspectos que toman en cuenta al medio ambiente. Si bien este tema va asociado a la tecnología utilizada, a la productividad del factor trabajo, no debemos dejar de lado que también va ligada a la percepción de la sociedad respecto a lo que se refiere a la calidad del medio ambiente. Es importante cuando se habla de un índice de calidad ambiental, tomar en cuenta que, no es solamente un número dentro de un determinado rango. Si dicho indicador no viene acompañado por la percepción de la población respecto al problema ambiental, difícilmente se podrán incorporar los costos en el circuito económico. Pienso que debe mirar la percepción de la gente respecto al indicador de calidad y su disponibilidad a pagar (tanto personas como empresas) para solucionar dicho problema.

Hello, the theory does not indicate that the impact should be positive. The first question is that the quality depends on its use and the perception of the users. It is not an objective or quantitative variable. The second question is whether it measures GDP growth or social welfare. In other words, do you take account of externalities?

Are you observing a correlation or an IV or dif in dif causation? I can think of many reasons for correlation related to growth potential of developing countries being larger potential catch up for adoption of existing technologies also being poor water quality countries - large potential for water important as well. 

After reviewing a number of papers with a result like this I have concluded that it is faster to make money than to die from bad water unless the water is REALLY bad. Sorry to be so pessimistic.