Septic Tank Operation
How a septic tank works and why it's important to have them cleaned periodically!
It's commonly misunderstood that in a properly functioning septic system, the septic tank has a consistently full liquid level that is about one foot from the opening of the tank. Not overflowing, but near the top. And once emptied after pumping, only takes only a week to refill to this level.
We see it time and time again. The homeowner will open the lid of their septic tank and be alarmed to see that the tank is nearly full but not overflowing, and they just recently had it pumped out. Though not experiencing any issues in the house, they will call us requesting that the tank be pumped out again. When in reality, this is normal. It's the operating level of the tank (PICTURED BELOW). It's always nearly full. The outgoing drain for the tank sits near the top of the tank. The purpose of a septic tank is to separate the incoming liquids and solids, trapping the solids in the tank. While allowing the liquid to pass through the tank to the leach field. Where the water is absorbed and filtered through the dirt back into the ground.
It's important to have the septic tank cleaned out periodically, every 3-5 years. Solid waste is constantly being trapped inside, building up and accumulating in the tank. If sludge buildup on the bottom of the tank becomes excessive, it begins to push out of the tank through the outlet baffle.
The trapping and settling of solids in the tank is assisted with the help of a component called a baffle. A properly designed tank will have 2 baffles minimum. One at the inlet of the tank and one at the outlet of the tank. The baffle at the inlet is designed to direct incoming wastewater downward. Moving the heavier solids to the bottom of the tank and minimizing incoming water turbulence in the tank which could stir up the already settled sludge at the bottom. It also prevents the floating scum layer from crowding the inlet pipe, potentially causing a blockage. Then there's the outlet baffle. This is the most important baffle in the tank. It allows the "clear water" from the middle liquid section of the tank to exit and prevents the floating scum layer in the tank from flowing out into the leach field, Causing a plugged leach field and premature system failure. And on newer systems the outlet baffle will be equipped with a filter to catch and prevent even more solid matter from exiting the tank. This filter will often times require cleaning every 6 month.