HOW DO I CARE FOR THE PITCHER PLANT

why are the trumpets on my pitcher plant turning brown

I would as the chlorine in the tap water will damage it.
welcome to GoY

I'm pretty new to these plants myself, but other GoYers have been helping me with them. Yes, you MUST water using rain water as they are very intolerant to any kind of minerals that are present in tap water. Also, it is normal for the pitchers to be turning brown at the ends (mine are doing the same). There shoudl be new shoots coming up in the middle of the plants that will develop into new pitchers to replace the old ones. I'm told the old ones can be snipped off using scissors, but I haven't done mine yet, as they still seem to be catching insects so presumably are still feeding the plants.

They are bog plants and must be kept wet i.e. standing in water, the whole time. I have my plants in trays of water about a third up the pots in depth - rain water of course. The compost mix should you wish to repot your plant is 50:50 peat:sharp sand and you can mix in some chopped spagnum moss to open it a little and use the moss to dress the top too to make it look nice. Hope this helps - they are facinating things to grow!