The ideal way is to position your tree away from direct sunlight, in as cool a place as possible, in a bucket or a purpose made Christmas tree stand filled with water. Natural water is fine, additives make no difference. However it’s important that the water does not run out or else the butt of the tree will seal up and even if you refill the stand with water it will be unable to suck up any more water as Christmas trees form an impermeable resin seal. Should you forget to refill the stand for a day or two the only solution in order for your Christmas tree to suck up more water is for you to take the tree down and make a fresh cut of 3 – 4 cms off the bottom of the tree so that it is able to replenish itself again.