My idea is for the personal water bottle filtration system.  A simple "dial counter" on the lid of the bottle would help for people to consume their 'daily water intake'.  It only needs to count to 8.  You could promote the idea of drinking more and keeping count.  Personally, I know it would help me to consume more water and I think it would help others too.  Additionally, if you packaged a "change your filter" sticker with the water bottle which would be used to put on your calendar to remind you to buy/change your water bottle filter.  Give people the math upfront...i.e. eight bottles a day means change your filter in ? weeks.  I believe the sales of your filters may in fact increase.  It's hard for us to know when to get a new filter.  In fact, I'm not sure when I should be changing mine at all!   

 

I hope you consider these ideas.  I know for me...it would make a difference!