Hi Alex, thank you for taking the time to write a review.
Firstly, I apologise for the delay in getting back to your email; we aim to reply within 72 hours - sorry if it's been longer than that.
Secondly, any water stored in a non-sterile container will develop bacteria growth. The key thing to remember is that the organic matter will never go through the filter to the tap and, as long as water is flowing through, it will have had 99.99% microbiological contaminants removed. My colleague will be in touch to talk about this is more detail.
The Carbon Filter should never be stored damp - you don't say whether that was left in place. It's only the Ultrafiltration Filter that must be stored with moisture.