Mexican Septic Tanks 101

I learned some new and interesting information about Mexican septic tanks, at least in this area.

I am actually somewhat familiar with septic tanks since decades ago I built a cesspool and learned about septic tanks in the process. I actually had a cesspool build for a hillside house I had (single bathroom below street level).

Usually, a septic tank has two chambers, the larger chanber where the solid waste goes initially and slowly dissolves. There is a wall dividing the two chambers and the wall is maybe a foot lower than the top of the tank.

As the solid waste dissolves (along with toilet paper and other "stuff'," the water level rises and the "water" with the dissolved waste flows over the wall into the smaller chamber and rises to a certain point where it exits the smaller chamber into a perforated pipe going out into a "leach field.

This "dirty water" is then dispersed into the ground through the holes in the pipe, which is closed at the end. The pipe can be paid on a bed or pea gravel (this in a couple of feet underground) allowing the water to dissipate over the length of the pipe, which can be as far away from the main house as you want.

Now comes the difference, or so I'm told.

In many fraccs where you have side-by-side houses, the tank is a sealed unit. Period. There are no holes in the bottom for the water to drain into the ground, and this is for two reasons, 1) The holes would end up being blocked by the less than microscopic debris in the water, and 2) It would be probably that the black-water would contaminate the ground water unless it is very deep and the black-water did have enough ground beloe it to filter it.

So what I am told is that at some point, I must simply have the tank pumped. When and how often? I was told I will know because either it will start backing up into the house and/or seep out through the "cold joint" between the tank walls and the top.

So of course the more water used, the quicker the tank will fill.

I guess my next project is to learn about recycling "grey-water."

Hope this was of interest so some.