Rain Water ? A Source Of Clean Drinking Water

RAIN WATER ? A SOURCE OF CLEAN DRINKING WATER

Water is vital for life and clean water will prevent most of the water-borne diseases. Shifting of seasons, untimely rains, prolonged droughtand other problems necessitated the Governments and people to look for alternatives to provide water for Agriculture and Domestic purposes. According to aWorld Report every fifth person on the planet will be affected by water by 2010. The situation is alarming and calls for judicious planning and execution of projects that utilize the abundant rainwater.

WHY HARVEST RAIN WATER?

Rainwater offers advantages in water quality for both irrigation and domestic use. Rainwater is naturally soft (unlike well water),contains almost no dissolved minerals or salts, is free of chemical treatment, and is a relatively reliable source of water for households. Rainwater collected and used on site can supplement or replace other sources of household water.

One of the beauties of rainwater harvesting systems is their flexibility. A system can be as simple as a whiskey barrel placed under a rain gutter down spout for watering a garden or as complex as an engineered,multi-tank, pumped and pressurized construction to supply residential and irrigation needs.

REVIVAL OF TRADITIONAL AND AGE OLD PRACTICES IN RAIN WATER HARVESTING:

Around 850 B.C., King Mesha of Moab was victorious in war and conquered a considerable territory east of the Jordan. This he proudly commemorated in the famous “Moabite Stone” text. One detail in King Mesha’s self-praise is :

I made two reservoirs in the midst of( qerkhah). Now there was no cistern in the city, so I said to all the people, ” Make you everyman a cistern in the house”(1)

This may be the first time that cisterns were mentioned in a text, but the device itself must have been invented considerably earlier. A progression has been suggested “from the primitive use or natural rock holes to the digging of open cisterns and finally the construction of roofed-over cisterns excavated in rock”(2). According to an ARCHAEOLOGICAL ENCYCLOPEDIA,

“THE FIRST CISTERNS WERE DUG IN THE MIDDLE AND LATE
BRONZE AGE92200-1200 B.C,: LW).

The rainwater that collected in them during the short rainy season would be enough for at least one dry season. In some parts of Palestine cisterns were the main(sometimes even the only) source of drinking water in peace time as well as in war time. In the early Iron Age(1200 ? 1000 B.C,; LW) the sides of cisterns began to be covered with watertight plaster, which considerably prolonged the time for which water could be stored. It was this important innovation that made it possible to extend the areas of settlement into the mountainous parts of the country (3).”

The rainwater was generally collected from the roof and courtyard of the house, in cities as well as in the countryside. A private cistern was seen as a necessary element in the planning of a new house in Tunis in the fourteenth century (4). A 1921 census in Jerusalem counted 7,000 cisterns collecting runoff water(5). One informant stated that even today in Amman it is legally required to include a cistern in any new house, but that some people fill them with piped water instead of rainwater (6).

REVIVAL OF TRADITIONAL TECHNOLOGIES?

Around the globe there is a tendency to revive the traditional technologies blending them with modern methods. the best proposition for such a revival could be ” RAINWATER HARVESTING”.

DRINKING WATER FROM RAIN WATER:

Perhaps one of the largest business covering large number of people in India in the last decade has been “MINERAL WATER”. There are scores of Mineral Water Manufacturers ranging from 200 ml packets to 20 liters can. This proves the conscious of the people for safe drinking water.

AN INNOVATIVE APPROACH TO PROVIDE SAFE DRINKING WATER:
We have many asbestos roofed structures. One such structure will be utilized to collect rainwater through a gutter and stored in a 1000 liter HPD tank which is commercially available in the market. The tank is provided at the bottom a tap to be connected to a filtering unit(RainPC). Initially the rainwater passes through a ” SAND FILTER” so that the visible impurities are removed. The RainPC has been found to have certain advantages:

* Small, compact rainwater purification device
* Simple ,scientifically developed
* Meets WHO Health Standards
* Designed for low-cost, appropriate application and works universally
* No power needed – - operates at low gravity pressure upwards
* maintains nearly constant volume irrespective of water pressure
* Simple, straightforward installation
* Easy to operate and maintain
* Robust, rugged compact construction.

METHODOLOGY:

The rainwater is collected during rainy season periodically and the quality of the filtered water for drinking purposes is evaluated.

The results are recorded for evaluation and practical and economic feasibility of the method.

References:

1. From the translation in Harding: Antiquities of Jordan,1967 p.43. Qerkhah is generally
identified with al-Karak
2. Evenari, Shanan & Tadmor: The Negev,1982 p.156
3. Archeological Encyclopedia of the Holy Land, 1972 p.332
4.Hakim: Arabic-Islamic Cities, 1986 p.171
5.Evenari,Shanan & Tadmor: The Negev, 1982 p.171
6.Lars Wahlin,The Family Cistern: 3,000 Years of Household Water Collection in Jordan,Sabour and Vikor,ETHNIC ENCOUNTER AND CULTURE CHANGE,Bergen/London 1997, 233-249

ADOPTING ? SODIS ? TO LOCAL CONDITIONS:

Many regions in the developing countries are lacking safe drinking water availability and it has always been a challenge to meet this demand. Thanks to the bright sun-shine available for most part of the year, one can judiciously plan to provide safe drinking water utilizing indeginous methods.

SODIS ?Solar disinfection method uses the sun?s ultraviolet radiation (UV) to improve the microbiological quality of drinking water. Synergies induced by radiation and thermal treatment have a significant effect on the die-off rate of microorganisms.

SODIS requires relatively clearer water with a turbidity less than 30 NTU (where NTU stands for Nephelometric Turbidity Unit and Nephelometer is a modern commercial instrument used to measure turbidity). Suspended particles in the water reduce the penetration of solar radiation into the water and protect microorganisms from being irradiated.

But traditional knowledge offers simple solutions to remove turbidity in water. A nut (wild growth in forests) called ?Chilla ginja? (in Telugu a South Indian Vernacular) has the effect of settling the turbidity. The local people rub the seed on a stone with water and make it into a paste. This paste is mixed with turbid water. In an hour all the turbidity settles down in a pot of water. Clear water is taken out and put in a separate pot for drinking. Generally people in rural areas collect the water from local storage tanks and hence turbidity.

Also ?TULASI? leaves (a plant worshipped in South India) have the property of water preservation. In temples the devotes are offered water mixed with Tulasi leaves, green camphor and cloves (longa). This is called ?Thirtham? in South India. The Thirtham lasts for a week although put in an open vessel.

SOME PROPOSED AREAS OF RESEARCH IN ?SODIS? ARE :

1. Utilizing Tulasi leaves, green camphor, cloves etc for preserving the water and also providing taste (as boiled water will be tasteless and as such people may not accept it). Even well to do people can adopt this method and place the bottles in refrigerator for later use.
2. Utilizing local methods to remove turbidity and then going in for SODIS.
3. Experimenting with black polyethylene sheet as base on which SODIS is put and to evaluate the degree of heat gain as well as its life (measuring degradation of material).
4. Instead of keeping it stable, orienting the SODIS towards the Sun. To find the angles suited for maximum efficiency.
5. The shape of the bottle- can be adopt small cross section pipes (polyethylene) available and use them by providing air-tight caps for quick heating.
6. What is the effect of fungus formation for continuously utilizing SODIS?
7. Polyethylene bottle turns brown after some days unless continuously cleaned. This is a very important aspect which determines the transmittance of sunlight.
8. During floods (which occur in most parts of India) providing drinking water becomes impossibility. Mainly water packets are dropped from above (using helicopters). The rain water harvesting using Rain PC as well as SODIS will be helpful in such cases. Mostly power will be cut-off during floods and SUN will be available.

?TECHNOLOGY IS CULTURE SPECIFIC?. As such what is suitable in Europe may not be applicable in Asia. Hence continuous application of local methods, knowledge, skills, material etc., will determine the acceptability of any technology. The success of CHEMICAL FERTILIZERS which ushered in ?GREEN REVOLUTION? is a testimony of Indian formers (illiterate?!) to adopt the modern technology.

Courtesy of Dr A. Jagadeesh