If available, a crumbled carbon layer can be added between the coarse sand and gravel layer.
The drum (tank) must be dark to prevent light from entering it and it must have a lid that covers it completely.
—– WE CAN IMPROVE IT: ——
In case of having a large drum (for example one of 200 liters), the following scheme could be carried out (from top to bottom):
1- Small stones (12.5 cm.)
2- Gravel (6 cm.)
3- Fine sand (6 cm.)
4- Gravel (2 cm.)
5- Shredded coal (3 cm.)
6- Gravel (3 cm.)
7- Small stones (12.5 cm.)
8- Large stones (25 cm.)
It is also convenient that the water outlet is at the top so that the tank is always full. This is achieved by placing instead of the tap, a new elbow and a vertical extension to the upper level of water, where we will place the outlet.
This way the debugging system will work much better.
It should be noted that this filter IS NOT MAGIC. It is worth saying that if the level of contamination of the water is high (for example with fecal coliforms), only an improvement in the index will be obtained, but it will still not be drinkable.
IT IS ALWAYS RECOMMENDED THAT AFTER PERFORMING THIS FILTERING THE WATER BE BOILED OR POTABILIZED WITH A COUPLE OF DROPS OF CHLORINE.