Domesticating pet bottles

After advent of plastic, one of the most engulfing applications of polycarbon has been drinking water bottles. People today flaunt plastic bottles all the time as if walking a pet.

Way back in 1889, founder of textile mills in this city, Shri Ranchhodlal Chhotalal had a vision and foresight to walk ahead of the times and rid Ahmedabad of epidemics by introducing underground drainage and water supply. Water from Kotarpur waterworks established by him was potable without any further treatment at home, for over a century and quarter. Suddenly, since last decade, water from any municipal source is seen unacceptable and pet bottles have found favour among citizens of this city. It doesn't matter if that 'branded' water, packed in some backyard of a bungalow or posh neighbourhood, is the same municipal water.

With this branded water, plastic comes free. Several thousands of them can be found in a single wedding party or in successful restaurants. In the US, 1,500 bottles are disposed off every second but India, with its deep tradition of recycling, has not yet embraced reuse of these plastic bottles.

While you may fetch some money by recycling/selling paper, no vendor will give you even five paisa for empty plastic bottles. Even if you do spend energy to recycle it, what you obtain at the end of the process is a small lump of reusable plastic.

But pet bottles, courtesy its cylindrical shape, serration along its length and monolithic mass, are designed to take wear and tear, abuses, press, stress and all other kinds of handling. Rather than melting it away, pet bottles can be used as a substitute to electrical bulbs (among several other uses) to save energy that is wasted by a 60 watt bulb, criminally illuminating a house for six hours, and sometimes in broad daylight in corner rooms of chawls and slums where our poor live.

With these slum houses jammed from three sides, the last room is invariably deprived of light and ventilation. Under compulsion, these poor families need to spend Rs60-100 a month to artificially light rooms in daylight hours. 

A satisfying experiment that we did was to push empty pet bottles through holes in ridges of a corrugated roof sheet. The slim waist of a water bottle comes in handy to hold the bottle in place. A sealant plugs the edges. With half the bottle outside and other portion inside, the inner part glows due to internal reflection within the bottle. This now becomes an effective source of illumination during daytime incurring no extra costs. MIT students independently have produced en masse thousands of such 'bulbs' in Philippines.

A study from Switzerland shows that if pet bottles are kept in the sun for 24 hours, it can kill germs and disinfect the water in it. This inspires another set of applications as inexpensive water storage & purification facility for slum dwellers.

Exploiting engineering aspects of this 'pet', we have successfully used plastic bottles filled with debris, fly ash or water residue from dump fill sites as bricks to make settlements. They are laid in course with mortar to construct walls.

Other applications include bottle bottoms cut and interlocked linearly with neck of another bottle to form storm water pipes, if laid vertically; upside down half-cut bottles filled with earth can emerge as tough paving blocks for walkways;these bottles can be cut laterally, filled with soil and hung over facades and used as pots for small plants.

This article does not say that pet bottles are friends and must be encouraged but rather it makes us understand that they can be put to some effective use, encouraging economic and environmental savings.