Recycling: Why is it written on water drinking bottle to crush them after use?

I think it's all about preventing counterfeiting / refilling and reselling of water. If the bottle has been crushed and deformed, you will notice the creases in the plastic if someone were to refill it and try and sell it as new. It's not to prevent you from refilling it and using it again, it's to prevent them from being salvaged en masse from the trash, refilled, and sold as new.

You will find the same instruction on disposable cans, disposable glasses and all disposable bottles. While for cans and glasses the main reason would be compact disposal as mentioned, for bottles I guess it is to prevent refilling and counterfeiting.

"CRUSH THE BOTTLE AFTER USE" is a long seen and often ignored message. Even i used to ignore this message as i was getting bottles to keep water at cheap prices. I had a two litre bottle which i had been using for the past 1 year. It was very comfortable to have that bottle as the frequency of refilling the bottle is very less. But, the last time i drank water form it, the water had an awful taste as well as smell. i thought that it would be of the water. So, i threw away the water and refilled the bottle. The refilled water tasted fine initially, became awful after few hours... This made me google for it and that's how i saw this question. On my small certain facts that i found are to promote recycling of plastic rather than the bottle falling of into the wrong trade or in a drain. it is safe to re use the bottle few number of times, but consequently there is probability of bacteria getting accumulated in the bottle. Another source says so "the plastic (called polyethylene terephthalate or PET) used in these bottles contains a potentially carcinogenic element(something called diethylhydroxylamine or DEHA). The bottles are safe for one-time use only; if you must keep them longer, it should be or no more than a few days, a week max, and keep them away from heat as well. Repeated washing and rinsing can cause the plastic to break down and the carcinogens (cancer-causing chemical agents) can leak into the water that YOU are drinking". overall, try to limit the usage of plastic bottles.

An ethical label on that product would say "Don't buy this and don't use it" But as others have pointed out, it's most likely about profit protection. The water bottler seriously doesn't care about space in the recycling bin, or they would not be selling their product in the first place! I disagree that this is for environmental reasons. Companies selling bottled water are in the business of getting you not to give a shit about the environment, while pretending like they care. They are probably hoping you'll think it's about the environment, so you'll do it, and protect their brand for them, allowing them to cause further destruction. The whole business is a needless environmental assault, so pretending this is for environmental reasons is something I find really amusing. There is no way this company gives a damn about the environment.

The main idea here is not to avoid counterfieting. It may be one of the reasons but certainly not the main reason. The main reason has to do with bacterial contamination. The PET plastic used in #1 bottles is porous, so it absorbs flavours and bacteria that you can't get rid of. There is also a concern that the heavy metal antimony can leach out of #1 bottles after they've been used for a long time (usually more than six months). This can trigger diarrhoea and upset stomachs.

First, crushing is to prevent these bottles from being quickly picked up by scavenging guys, the garbage collectors, so that those bottles can not be reused 'as-is' by counterfeit and duplicate brands. Second, is the type of plastic used in the manufacturing of these bottles. These water bottles or any packaged food/beverage containers are made of PVC(Poly Vinyl Chloride) and Styrene which, are not considered safe for longer run. So these should be discontinued as early as possible. The only plastic recommended for plastic containers for daily use is PET or PETE. (You can look for a text PET under your fridge water bottles). Other safe plastic types are HDPE, LDPE and Polypropylene. (way too jargons but you can read about them). I hope you get that, main reason behind that message is your health.