• Joseph

Septic Tank Surprise


I love being surprised as much as anyone, but I was recently reminded that not all surprises are good. In fact, sometimes they stink, figuratively and—in my case—literally.

This past winter was a particularly harsh one here in New England, and as the last of the snow finally melted away, I noticed a depression in our front lawn. Upon further investigation, and a bit of digging around, I discovered that one corner of our 1,250-gallon concrete septic tank was gone. I couldn’t believe my eyes. (My nose, yes, but not my eyes.) A section of concrete measuring about 14 in. deep x 4 ft. wide x 6 ft. long was simply no longer there. It had vaporized, vanished without a trace. The only artifact unearthed was a U-shaped piece of rebar that had been cast into the tank’s clean-out cover to serve as a handle.


I was astounded because when the septic tank was installed 24 years ago, I thought it would last forever. After all what could go wrong, it’s just a concrete box buried in the ground. But after discovering the damage, I called an excavator and got a second not-so-welcoming surprise: He said this is a very common problem and that he digs up and replaces rotted septic tanks all the time. To replace my tank would cost $3,200. Surprise!


If you’re not familiar with the inner workings of a septic system, here are the basics: The tank has a concrete baffle (divider) running down the middle, separating the tank into two chambers. But, the baffle doesn’t extend all the way to the top of the tank. When you flush the toilet, take a shower, or do laundry, all that water and waste flows out the house and into the first chamber. Over time, the solid waste settles to the bottom, and the liquid waste fills the first chamber and eventually spills over the baffle and into second chamber. The liquid waste flows into the leach fields where it eventually soaks into the ground. Every few years it’s necessary to have the solid waste pumped out and brought to a waste-treatment facility.


Now for the biggest surprise of all: Liquid human waste produces a gas that eats through concrete. That’s right, it’s commonly known that septic gases corrode concrete, and yet, they continue to make septic tanks out of concrete. To whom does this make sense?! It makes no more sense than making umbrellas out of newsprint.


Anyway, I had no choice but to dig up the old, rotted septic tank and replace it with a new one. Only this time, having learned my lesson, I purchased a plastic tank that’s completely impervious to corrosive gases. Now, the plastic tank did cost considerably more than a new concrete tank—about 30% more—but at least I won’t have to worry about any more unpleasant surprises.

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