In one sentence, describe what the following article is about:

Find a sterile bottle that's large enough to hold the water and pour 4 cups (0.95L) of warm tap water directly into it. To sterilize the bottle, boil it in water for 5 minutes or run it through your dishwasher on the hottest setting. Although tap water is safe to use, you can also use distilled water. The water should be comfortably warm, somewhere between 98 and 104F (37 and 40C). Use a measuring spoon to drop the table salt right into the bottle with the warm water. It's important not to eyeball the amount of salt or the solution might not be the correct strength. Ensure the cap is screwed on tightly so no water leaks and vigorously shake the bottle until you see the salt dissolve in the water. This should take around 30 seconds. The saline solution will be clear since there's very little salt in comparison to the water. Your doctor should tell you how much saline solution to use, but adults, in general, will need to pour 2 cups (470ml) of the solution into the bag. Kids between the ages of 6 and 12 should get 112 cups (350ml) of saline solution while children between the ages of 2 and 6 should use 34 cup (180ml). For an extra laxative effect, your doctor might recommend adding 2 to 6 teaspoons (9.9 to 29.6ml) of glycerin or prescription medication to treat bowel conditions, such as inflammatory bowel disease or ulcerative colitis. Follow your doctor's prescription when adding these medications to an enema. You may need to hold them longer or take them at specific times of the day.
Pour 4 cups (0.95L) of warm water into a large clean bottle. Add 2 teaspoons (11 g) of table salt to the bottle. Seal the bottle shut and shake it until the salt dissolves. Pour the recommended amount of warm saline into the enema bag. Put glycerin or prescription medication into the enema bag if your doctor recommends it.