Here in central Florida we have what is considered pretty good tap water (for
Florida anyway), 140 ppm TDS (total disolved solids). I have never had these
solutes identified by testing, but likely in our area there is calcium,
sodium chloride plus flourides. Rain water here on the coast is not really a
good option, collecting from roofs will lead to a good bit of sea-salt
contamination. Still for outdoor CP like VFTs, I do catch the rain, and they
get flushed with direct rain now and again.
As to Nepenthes, for years I used the local tap water on the plants. Most did
fair, but some species like N. albo-marginata, madagascariensis, and well as
many highland plants did poorly. At a friend's suggestion I bought an R.O.
unit and installed it together with a catch barrel and pump, so as to have
R.O. on demand. Within six months the results were amazing, some of the
difficult species became easy, and the easy ones produced larger pitchers
with better color (N. ampullaria was amazing!). Plants produced more
inflorescences and seedlings were easier to raise.
Water alone is only one factor in Nepenthes care, but most of all the other
parameters during the switch to R.O. remained the same and the change was
dramatic. In any case, unless you are raising mangroves improving the purity
of your water can't hurt.
Also about baskets: I grow about 1/2 of my plants in baskets, mostly the
highland ones, but a few lowland species as well. Baskets are not needed for
many species and the plants will need frequent watering in a greenhouse
situation, but species that like more open mixes seem to benefit from
baskets.
Cliff