As you can see in the first illustration, the first 3 vertical standing 75 gallon plastic olive drums act merely as water clarifiers. There are baffles in all three so that only the cleanest water exits from one and enters the next. These were part of the first upgrade. All 3 tanks do different things with the gray water to clarify it. When the water from our drains enters the first tank, it’s directed in such a way that it swirls it in a vortex. When the water reaches the 3rd tank it’s released at the bottom so as to accentuate the settling process and exits through its baffle near the top. Right this minute I can’t remember how I designed second tank, but it’s different from #1 and #3.
The 4th filter (illustration 2) lies horizontally and is filled with huge chunks of lava rock. It also acts as a surge tank so the next 3 aggregate filled vertical drums #5, #6 and #7 (illustration 3) can take their good old time doing their job. By surge tank I mean if #5 #6 and #7 aggregate filters can only handle 5 gallons a minute, you can still pour 50 gallons down the drain. #5 is filled with crushed lava rock and #6 and #7 are filled with aggregate (stones) that get smaller and smaller until the water has to percolate through sand and then fine road ash. I was just starting to assemble these filters to percolate the water downward through the aggregate when I was suddenly struck with the logic of percolating the water upward from the bottom so I changed their design in mid construction. That’s because, as I said earlier, the upward flow works with the tendency of impurities to settle down. That meant I had to pack the aggregates into their drums in reverse, which is larger grade on the bottom graduating to a finer grade on top