You will need a barrel, a rope and a pulley on a pole. Oh and something to make holes in a barrel with.

To compile:

• rope the barrel and lay the rest of the rope over the pulley
• drive the pole into the ground next to your desired source of water
• optionally, keep the barrel’s lid openable
• make holes in the barrel in a convenient position, such that the holes will face downwards when you eventually mast the barrel

To charge:

• Set the barrel in the water source and wait until the barrel is full of water (optionally open the lid at this point)
• If you optionally opened the lid before, then mandatorily close the lid, now
• Pull the rope from the other side of the pulley such that the barrel goes up
• Let the water pour from the barrel and have fun with the shower