A septic tank that melt water will surely flood

When choosing a septic tank design, most combine the principle of a cesspool and a well with water filtration (without a bottom) in the scheme. It happens that for greater reliability in the operation of the system, a third well of concrete rings is added:

The first well will have to be pumped out frequently. Because it accumulates solid waste.

Some owners of country houses, in an effort to call a car with the "Pumping of septic tanks" service as little as possible, make walls of wells with holes for better water filtration. To do this, bricks are placed in the seams between the rings or a well of brickwork with holes is made:

I consider this a mistake for those regions and places where a lot of snow falls in winter (a large amount of spring melt water). Even if the snow is cleared around such a septic tank by spring, melt water will still seep inside and additionally fill such a well.

This will be especially noticeable on a slope, even a small one. My site just has a slight slope and every spring it drowns a hole in the street toilet located at the bottom of the site. Even the blind area around the building did not help.

You can also understand this technique when you make a small cesspool for a bath. You use the sauna maximum once a week (if it is not for commercial use).

The worst thing is when the manufacturers of such concrete rings offer them in their assortment, but do not warn about such a possibility of filling the septic tank with melt water. Water penetrates even more intensively into the well of the septic tank when the rings are sprinkled with coarse gravel - sort of like for better water leaving the septic tank. And in the spring it works the other way around.

There are self-builders who manage to incorrectly install a plastic septic tank with aeration and a drain of purified water. Or they cannot provide for the rise of groundwater from the source of thawed to the installation site of the septic tank. And then the following happens:

A plastic septic tank floats up in waterlogged soils like a float (there is air inside it). The reason for this is that meltwater or groundwater liquefies the soil (as written above), or the lack of a flow of purified water. Water runoff freezes or groundwater rises in spring.

Everything is clearly visible in these diagrams.

1. Imagine, groundwater rose, and a well of concrete rings flooded. Next, the plastic container will overflow. Water from it will begin to overflow through the neck. This will soften the soil. And if the aerator continues to work, then the air inside the septic tank will give less weight to the liquid waste and the septic tank will float.

2. The same will happen in the second scheme if the water drainage channel freezes. These schemes are aerated for warm climates. In frosty regions with temperatures up to -30... -40 gr. they are not effective.

But that, as they say, is not all possible problems. When soils are saturated with melt water (or from an overflow of a septic tank) in the off-season (in spring there are also severe frosts), an intensified frost heaving will begin. And it can deform or even tear a plastic septic tank:

The conclusion is this: pay attention to the groundwater level in your area. And consider the amount of melt water. If you live in oil-snow regions or in a region without snow at all - there is no reason to worry that your septic tank with a "perforation" will flood.

In my opinion, there is nothing more reliable than a septic tank made of concrete rings. But what kind of diameter to choose rings and what design of a septic tank, consisting of how many wells - I will talk about this in the next part.

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Photos are taken from open sources, from Yandex. Pictures

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