Storing celery and carrots in water involves partially filling a container with water and submerging the vegetables. It is also possible to stand celery upright in a glass of water.
To store celery in water, first remove the stalks from the base. Cut away the leaves, and chop the stalks in half. For carrots, remove the tops, and cut them in half.
Place the vegetables into a container. The container should be either glass or plastic. There should be at least 1 inch of headroom between the top of the vegetables and the rim of the container.
Fill the container with filtered water. Use plastic wrap or the container's top to seal the vegetables inside. Store the vegetables inside the refrigerator. Change the water every day, or at least every other day. The vegetables can stay fresh up to a week stored this way.
To store the celery upright, remove the stalks from the base, but keep the leaves intact. Trim the bottoms, as if preparing flowers for a vase.
Fill a glass jar halfway with water. Place the cut side of the celery into the water. Cover the top with a plastic bag. Refresh the water daily. This method doesn't work as well for carrots, but it does work with fresh herbs.