As ubiquitous as the sili sili bags: Plastic water tanks too can be deadly | Sunday Observer

As ubiquitous as the sili sili bags: Plastic water tanks too can be deadly

Is the water you drink stored in a plastic tank? If it is, then think twice before take that next sip to quench your thirst. You could be ingesting deadly chemicals which can cause serious health impacts that could last for life and shorten your lifespan. This warning comes from the Head of the Poisons Information Centre , National Hospital of Sri Lanka, Dr Waruna Gunathileka who says, his Unit has world scientific evidence to back up their claim. “The chemicals that are leached out from these containers are highly toxic. They can cause cancer, affect sperm production in males and cause hormonal changes such as, early puberty in females. It can also result in early births”, he told the Sunday Observer. “Sri Lanka is one of the few countries which use these containers, banned or phased out in most other countries, including the developed western nations. It is high time they do the same thing in our country”, he noted. Ubiquitous, convenient and cheap, plastic water tanks are to be found everywhere in our island, from East to West, North to South. Look around you and you will see them perched atop rooftops in almost every household including apartment buildings and newly constructed buildings, as the sole means of obtaining drinking water.

Discounted prices

During a recent drive through some of the most congested parts of the city, this writer saw even half built houses and small wayside business outlets, whose rooftops were decorated with these barrel shaped black plastic water storage tanks. Several small shops that seemed to have sprung up overnight, were seen even flagging down motorists and inviting customers to buy them at discounted prices. Judging by the number of customers at a small sales outlet in Dematagoda where several trucks were being loaded with these containers of varying sizes from small, medium to large, it was obvious there were plenty of takers. “During a scarcity of water or water cuts, the demand often exceeds our supply”, an owner of a small sales outlet at Wattala told this writer. A former food vendor, he decided to convert his boutique into a sales outlet for plastic water tanks and says it was the wisest decision he had made. “Business is thriving. I even supply these tanks to my children’s schools and this year I’m expecting more orders” he says, with eager anticipation. But, does he know that these same profit making products contained toxic chemicals when exposed to the sun and could harm both his customers and his family? I asked. Giving a negative response, the man obviously bewildered and shocked by this startling revelation, said, “ This is the first time I heard that these containers could actually cause health problems. No one informed us about the negative health impacts. The manufacturers simply assured us they could be used to provide enough water to people when their water supply ran dry. And, because they are cheap, most of our customers don’t even bother to check if there is a trade mark “.


“It is a matter of ignorance. There is still widespread ignorance on the dangers of plastic water tank usage. There is also a lack of uniform standards by manufacturers. My question is, who monitors them?. Who is responsible for this? More awareness raising on this is what is needed to fill this gap”, says Dr Gunethilaka.. “These tanks must be phased out with a specific time frame, to give more time for alternative water storage containers to be developed”.

Responding to a question on how exactly the water in these tanks end up toxic, and what signs to look out for, he said,. “The danger arises when these tanks are placed high above the earth’s surface , usually on roof tops, and exposed to the extreme heat of the sun all day. What most people don’t know is that they are made of polymer which is a petroleum derivative and contain harmful chemicals that leach out into the water when exposed to strong sunlight. As Sri Lanka is a tropical country where we experience sunny weather all year long, the risk for such exposure is much higher than countries in colder climates. Hence, it is best they are placed where they are not exposed to the sun “.

Warning that plastic could affect the biological properties of water and lead to bacteria formation, it could alter the taste of the water,” he said. “We have had recent complaints from the public regarding an odd taste in the water which is probably due to this naturally occurring phenomenon in plastic,” he informed. So what options did he have in mind for storing water? “Cement or stainless steel tanks are safer. They should switch to these, especially, when building houses in the future, as they been found to contain no chemicals when exposed to the sun,” he said.

Another frequently used plastic material which could also adversely affect the health of the Lankan public is PVC. “ Polyvinyl Chloride( PVC) pipes should be phased out as in the West.

This is also used in consumer products such as lunch boxes and water bottles. Metal lead frequently added to PVC to improve workability and stability, can leach into water as well, following degradation over a period of time, wear and tear. This can result in surface embrittlement and micro cracking, which can form micro particles. These act as sponges and soak up POPS(,PERSISTANT ORGANIC POLLUTANTS), which leach into the water and changes its taste. Besides this, plastic tanks affect biological properties of water as well. Different microorganisms and worms can also multiply at faster rate inside these plastic tanks compared with clay or cement tanks.”, Dr Gunathileka said.

International Code

He also offered advice on selecting safe lunch boxes for schoolchildren. “Choose only those that carry the international code of a fork and spoon, for storing food,” he advised. But taking into account the proliferation of plastic lunch boxes available at all supermarkets and pavement shops, we asked if there was a likelihood of imitation or fakes.

Citing some examples where some takeaway parcels from wayside restaurants were now carrying this same logo, we asked if the Unit could offer suggestions on filling these gaps. “Standards should be monitored – and maintained to ensure quality. This could be done by the Sri Lanka Standards Institute (SLSI), Ministries of Trade and Environmental Authority .

Post marketing surveillance of plastic water storage containers should also be done continuously, noting that it was a multi disciplinary effort involving all the stakeholders . “Our role is to provide information backed by scientific evidence. To clarify any issue regarding plastic water containers our hotline is 2676193”.


Global research has also found that the dissolved chemicals, when ingested by people through drinking water, have many adverse effects on the human body. For instance, Bisphenol A severely affects the endocrine system and is also known to cause cancer, asthma, cardiac problems and reproductive system irregularities in women.

These problems are more prevalent in infants and children, than adults. A recent report by the National Institute of Environmental Health Sciences, USA, further states: “Polyethylene Terephthalate (PET) is widely used to make clear plastic bottles for bottled water and other beverages, condiments and cosmetics. There is concern that estrogenic chemicals such as, phthalates, may leach into the contents from bottles made from PET, although PET is not a phthalate derivative.

The contents of the PET bottle, and the temperature at which it is stored, both, appear to influence the rate and magnitude of leaching. Endocrine disruptor other than phthalates, specifically antimony, may also contribute to the endocrine-disrupting effect of water from PET containers,” the study stated.

Global studies on toxicity in plastic water tanks

The surge in the use of plastic water storage tanks has led to the annual production doubling in the last 15 years, in some countries, especially, in poorer nations, where they are generally preferred as they cost less, are made of stronger material, are light-weight and easy to manoeuvre than many other alternatives, research has revealed.

Researchers however maintain that lack of awareness and adequate knowledge about the toxicity caused by the plastic and synthetic chemicals used in these tanks has raised serious concerns. According to a US researcher, “Despite claims by manufacturers regarding their safety, these plastic tanks have more drawbacks than benefits. Plastic water tanks can only be considered a good alternative for ceramic or cement water tanks if they were resistant to heat and Ultraviolet (UV) rays and manufactured from non-toxic material that does not affect the odour and taste of water.”

He further noted that, plastic tanks and bottles available in the market today were mostly manufactured from Polyethylene (PE), Polypropylene (PP), Bisphenol (BPA), High Density Polyethylene (HDPE), Polyethylene Terephthalate (PET) and cross-linked Polyethylene (PEX), or Thermoplastic Polymer, which have very well-known health risks for end users.

“These chemicals start mixing with water when used for long, and when these reservoirs are washed with detergents.

Leaching also happens when they are exposed to UV rays, high temperature as well as from natural breakdown. When these plastic tanks are exposed to strong heat, the chemicals start to melt down and mix with water. These plastics are also known to alter the physical properties of water,” the researcher noted..