The steps are:

• Prepare the bottle with a piece of string and attach a clean weight to the sampling bottle. (Figure 17.6)
• Take a 20 m length of clean string rolled around a stick and tie it to the bottle string.
• Open the bottle as described above.
• Lower the bottle, weighed down by the weight, into the well, unwinding the string slowly. Do not allow the bottle to touch the sides of the well.
• Immerse the bottle completely in the water and lower it well below the surface but without hitting the bottom or disturbing any sediment.
• Raise the bottle when it is judged to be filled, rewind the string on the stick to bring up the bottle. If the bottle is completely full, discard some water to provide an air space.
• Stopper or cap the bottle as described previously.