Leaf Curl or Leaf Roll

[murihikukid]

Hi...Everytime I open my greenhouse's sliding door I am confronted with curly leaf although I have got a pretty good crop this season no doubt due to amazing weather we are having...

Anyway its been on my mind for some time now and I have been trying to think what I have done right from my first plant put in the greenhouse.....and it must be something I have done..
With the best of intentions at the start of the season I decided to water my plants with rain water so I purchased some 200 gallon Blue Plastic Drums.....Cut off the tops and thoroughly washed them with dish washer and then a detergent.....tipping them over between and then filling them with tap water for a final rinse....and letting them dry..... I then put 3 of these drums under the runoff pipes for my house roof and 1 under the runoff for my greenhouse roof....
Thats where all my rain water came from....??

You have probably guessed where I am going to here....I am no chemist or expert on chemicals etc but I now understand that the "unknown" chemicals that were originally in the drums may have left a residue in the plastic and even with my washing with dishwasher etc rain water collected may have got contaminated and of course it was put on the soil of my plants.....Sadly I will never know if my theory is right.......
Regards Ron