I use tap water for my Neps too, so far no problems. However, I avoid using untreated water for other CPs, especially Sarracenia as sometimes the leaves come up weird - twisted or bent.
Anyone's grown N.merrilliana before? I have one small plant that's taking forever to grow - 14 months and still a 6" leafspan!
Cindy: You might want to try poking N.gracilis cuttings straight into CP medium. Some plants, esp. gracilis and rafflesiana, root better that way than immersion in water. BTW, sent you a PM.
Guqin - for Neps, you might want to try Malesiana ... they have a huge variety at rather cheap prices. For large N.veitchii (lowland), you can try asking Alvin, he has several plants that are already forming 4-5" pitchers.