Fill a pan with enough filtered water to flush the wound.
Turn up the heat to bring the water to a steady, slow, rolling boil.
Put a lid on the pan and leave it to boil for five minutes.
Turn the heat off.
Remove the pot's lid. Add 1 level teaspoon of non-iodized salt for every 2 cups of sterile water. Stir until the salt dissolves. Replace the lid.
Leave the water in the pot to cool down to room temperature. Leave it on the stove or place the lidded pot in the refrigerator or freezer to accelerate cool-down time. Do not place ice in the water to cool it down. The ice is unlikely to be sterile.
Use the sterile irrigation solution immediately or store it in a sterile container. Write the date on the container. Store the unopened container in the refrigerator for no more than three days. After three days you must make a new solution and re-sterilize the container.