Very carefully, pour the lye from the cup into the pitcher of rain water (if you do not have rain water you can use distilled water). Never pour water into lye as this can cause the solution to splash up and out of the pitcher. If the lye and water solution does come into contact with the skin, rinse the area with vinegar and then running water. If the lye splashes into the eyes, immediately follow the manufacturer's directions on the lye container. Lye is a caustic soda and can be fatal if swallowed! Always keep lye out of the reach of children and pets.  I store it in a high cupboard where children can not reach it. At al times when working with lye make sure to wear protective eye wear and clothing. Be careful not to breathe in any lye crystals as they can cause serious burns, I mix my lye and water on the stove and run the exhaust fan to clear the fumes out of the house.  On a nice day I mix it outside on the deck.