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Brazil has 11.6% of the worlds fresh water.

70% of Brazil’s water is in the Amazon where only 3% of the population lives.

Region                   Water                      Surface area                    Population

North                    68.50%                     45.30%                                  6.98%

Central West      15.70%                      18.80%                                 6.41%

South                     6.50%                          6.80%                               15.05%

South East           6.00%                          10.80%                            42.65%

North East           3.30%                          18.30%                             28.91%

Source: Secretariat for hydro resources of the Ministry of the Environment.

As you can see from the table above, the North East region (where I live) is large and has very little water.  During the rainy season, the coast receives sufficient rainfall to supply the needs of the population, however there are justified fears that too great an increase in the population and their subsequent use of water, brought about by the promotion of tourism, holiday resorts and golf courses along the NE coastline,  will place a burden on the water supply that it is unable to meet (as has happened around the world, most notably in some Spanish resorts).

The whole of the North East inland area is suffering from continual drought with, according to some estimates, below average rainfall for the last 50 years, as a consequence the area is undergoing the process of desertification. The Brazilian government have undertaken the  highly controversial plan of diverting water from the San Francisco river, in an attempt to alleviate the problems of drought.

As in many other countries,  a large percentage of the population also faces a polluted water supply. Prainha Do Canto Verde became the first village in Brazil to benefit from the technology of SODIS (Solar Water Disinfection). It uses infrared light to heat the water and ultraviolet light to kill the micro-organisms. It is a simple, cheap and very efficient way of disinfecting water.

Sodis is successfully used in Bolivia, Burkina Faso, China, Colombia, Indonesia, Thailand, Togo and Peru. It was developed by EAWAG (Swiss Federal Institute for Environmental Science and Technology.) and CINARA (Institute of investigation and Development of Drinking Water, Sanitation and Conservation of Water resources.) in Cali, Columbia.

The World Health Organisation approves of and promotes the use of Sodis.

The method is simple:

Take a clear plastic bottle (it must not be coloured) of the sort used for fizzy drinks (PET).

Clean the bottle and ¾ fill with clear water (if necessary filter the water first).

Shake the bottle for 5 seconds

Completely fill the bottle, do up the lid.

Lay the bottle horizontally in a position where it will be exposed to full sun.

After 10 hours of uninterrupted sun exposure the water is safe to drink.

On days with partial cloud cover, the bottles can be left for two days to complete the process.

SODIS is not recommended when there is continual cloud cover.

For the process to work, the bottles must be:

Clear plastic.

A maximum of 2 litres

A maximum of 12 cm for the sun to penetrate all parts of the bottle

In good condition (clear and unscratched).

*The water used must be clear with a maximum turbidity of 30UT

*we are given a turbid metre to check this, the word SODIS written in light grey letters, if it cant be read through a bottle of water, the water is not clear enough, or the bottle is too scratched to use.

When I was explaining the system to a friend of mine, she expressed concern that the plastic bottles leach out one of the female hormones, but the bottles contain a finite quantity of the hormone and once its gone its gone, the bottles are reused multiple times. The risk of an increased oestrogen intake, pales in comparison  to the life threatening water born diseases that SODIS can and does eradicate.  Water treated by the SODIS method tastes good and is free, (once you have your supply of bottles) therefore making it available to the poorest of peoples.

During the rainy season, the cloud cover is such that SODIS can not operate effectively. At these times we have to boil our water or add chlorine drops. Boiling takes time and costs money (in fuel) and chlorine leaves a taste (as well as possible health risks from ingesting the chemical). The other alternative is to buy bottled mineral water, beyond the reach of the poor.

SODIS cannot alter the physical chemistry of the water (sand, mud, fertilizers etc), and cannot be used where the water is turbid.

Once the bottles are no longer of a condition suitable for use, I fill them with sand and sink them into the garden to act as edging for the plant beds, pathways and so on. They make an effective barrier against the shifting sand and it keeps them out of the rubbish tips.

Recycling projects use the plastic bottles in a variety of ways, from handbags to furniture. PET bottles have a remarkably long life, some sources say we don’t yet know how long they take to break down, other sources say an estimated 100 years, that’s frightening when you think that plastic has only been around for a little over 50 years.

©Claire Pattison Valente 2009

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