Rain barrel floater

This is a floater for rain barrels. It is supposed to be filled with sand to increase its weight. The top can be connected with a string to the hatch of the pipe of the rain gutter. Once the water level of the rain barrel sinks to a certain level, by for example using the water for watering the plants in the garden, the floater will pull open the hatch and water will run into the barrel again. Once the water level has risen again, the floater will automatically close the hatch again, preventing the barrel from overflowing with water.