For all of my nepenthes i use the regular tap water! I live in the city next to L.A, Long Beach. The water here doesnt seem to harm my nepenthes at all and before you say or think anything let me just tell you from experience! i grew nepenthes about 2-3 years ago and i used the same method and they were fine. i started again in 2005 and i still use the same method for these. i know someone may say that the salt content in the water accumilates heavly @ the bottom of the pot especially on the saucer, and i am aware of that. so the first thing i do before i accutaly give the tap water to my nepenthes is i fill up a pitcher up with tap water and let it sit inside/outside for about 10-24 hrs. i do this so the chlorine in the water evaporates slowly. the flollowing day i use it. thats all. i really dont want to buy water such as distilled or reverse... so i just go with what i have! a filter would be nice but dont have the time to buy and install one.