I recently came across another chain mail, about the numbers below plastic bottles we use. According to this mail, the number (generally within a triangle) written at the bottom, which ranges from one to seven, indicates how many times that particular plastic is recycled in reverse order. I dug a little deeper. Apparently, the number printed has nothing to do with the number of times plastic has been recycled. It’s just the type of plastic which is used for that particular bottle. 5 is polypropylene and 1 is polyethlyene terephthalate etc etc.
One primary use of having the numbers if to help recyclers to sort into appropriate groups. In other words, identification number.
1 – PET, polyethlyene terephthalate
2 – HDPE, high-density polyethylene
3 – PVC, polyvinyl chloride
4 – LDPE, low-density polyethylene
5 – PP, polypropylene
6 – PS/PS-E, polystyrene / expanded polystyrene
7 – OTHER, resins or multi-materials

Here is copy paste of that mail
How to avoid:Check on the bottom of the bottle there is a triangle sign and there will be a number on it. If the number is higher than or equal to 5 –> then this bottle is safe to use.Whatever number under 5, will release the chemical. For most bottle water, the number is 1.Did you know chemical released by plastic water bottles can cause cancer(It is not the water that affecting you but the chemical releasing from the bottle)Pass this to all your friends and also make them aware of it…How to avoid:Check on the bottom of the bottle there is a triangle sign and there will be a number on it. If the number is higher than or equal to 5 –> then this bottle is safe to use.
Whatever number under 5, will release the chemical. For most bottle water, the number is 1.
Did you know chemical released by plastic water bottles can cause cancer(It is not the water that affecting you but the chemical releasing from the bottle)
Pass this to all your friends and also make them aware of it…