First, what is your tap water source (city, well, rainwater cystern, etc)? If the tap water is treated for human consumption it will be "safe" for chams, but it might be hard (full of mineral salts). This can build up on your plants but not hurt the cham. If your house water runs through a softener this will help. Distilled water (basically is condensed steam from boiling) has all minerals and everything taken out, so your cham will not get micronutrients from drinking it. Filtered water will depend totally on what the filter is designed to take out (sulphur, chlorine, rust, heavy metals). Bottled water will again depend totally on the source well, but if it is for human use it is safe. Basically, any water that is safe for human consumption should be safe for chams. Bottled water may taste better than your tap water or not contain chlorine. If you want to find out what's in your tap water either call your city water district or get a home test kit. I wouldn't bother buying distilled water, and if your tap water is chlorinated you might choose to use bottled instead.