Question
So I understand that carnivorous plants like to have distilled or rain water, I was wondering, since hard water burns the roots, if it is okay to use hard water from the tap in humidity trays or even to fill up a dry pitcher (not sure if this is wise but I have been filling pitchers)? Also, by collection rainwater, the buckets tend to get a lot of muck in them, the plants seem okay, but I want to be sure it's okay if theres a little junk that gets into the soil?
Is it wise to fill pitchers?
Can I use hard water in a humidity tray, or to fill pitchers?
Is mucky rainwater okay to use?
How can I keep rainwater?

Answer
Yes, you can use tap water or hard water in your humidity trays.  However, you will end up with lots of mineral buildup in the tray after a few months, which may not look terribly attractive.  If you're OK with this, then this is perfectly fine to do.  Just make sure you don't use hard water in the soil of your plants.

It's not at all necessary to fill the pitchers of your Nepenthes with water.  It's not something that we do at our nursery nor something that we actively advocate.  It's OK to do so.  We don't think it's necessary for the overall well being of the plant.  If you choose to do so, use distilled water only.

Mucky rainwater is OK to use if you don't see any adverse effects with your plants.  In the wild, the water isn't always crystal clear or absolutely clean.  As long as you're not getting minerals from your roof (zinc and copper), rainwater is fine.

You will need to do an internet search for appropriate collection and storage systems.  It all depends on your budget and the amount of rain you typically get.  There are many different methods.  You just have to read about them to figure out which one would work best for your particular home.

Good growing!
Jacob Farin