Understanding and Caring for Your Septic
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WHO has a septic system? Households that are not served by public sewers usually depend on septic tank systems to treat and dispose of wastewater. A well designed, installed, and maintained septic system can provide years of reliable low-cost service. When these systems fail to operate effectively, property damage, ground and surface water pollution, and disease outbreaks can occur. Therefore, it makes good sense to understand and care for your septic tank system.
There are many different types of septic tank systems that can fit a wide range of soil and site conditions. The following information will help you to understand a simple type of septic system, and keep it operating safely at the lowest possible cost.
WHAT is a septic tank? The typical septic tank is a large buried rectangular or cylindrical container made of concrete, fiberglass, or polyethylene.
HOW does it work? Wastewater from your toilet, bath, kitchen, and laundry flows into the tank. Heavy solids settle to the bottom where bacterial action partially decomposes them to digested sludge and gases. Most of the lighter solids, such as fats and grease, rise to the top and form a scum layer. Septic tanks may have one or two compartments. Two compartment tanks do a better job of settling solids and are required for new systems. Tees or baffles are provided at the tank's inlet and outlet pipes. The inlet tee slows the incoming wastes and reduces disturbance of the settled sludge. The outlet tee keeps the solids or scum in the tank. All tanks should have accessible covers for checking the condition of the baffles and for pumping both compartments. If risers extend from the tank to or above the ground surface, they should be secure to prevent accidental entry into the tank.
WHY do I need to pump my septic tank? Solids that are not decomposed remain in the septic tank. If not removed by periodic pumping, solids will accumulate until they eventually overflow into the distribution box and drain field, causing damage and possible septic backups.
WHERE is the tank? Most tanks are located about 8 – 10 feet out from the house. Look for a dead patch or particularly green patch of grass. It should be where the main water line leads out of the house. It is often on the same side of the house as your ground floor washroom.
WHEN should a tank be pumped? Most septic tanks need to be pumped every 3 years, depending on tank size, number of people using the system, and the amount and type of solids entering the tank.
The Drain Field
The drain field receives septic tank effluent. It has a network of perforated pipes laid in gravel-filled trenches (2 – 3 feet wide), or beds (over 3 feet wide) in the soil. Wastewater trickles out of the pipes, through the gravel layer, and into the soil. The size and type of drain field depends on the estimated daily wastewater flow and soil conditions.
The soil below the drain field provides the final treatment and disposal of the septic tank effluent. After the effluent has passed into the soil, most of it percolates downward and outward, eventually entering the groundwater. A small percentage is taken up by plants through their roots, or evaporates from the soil. The soil filters effluent as it passes through the pore spaces. Chemical and biological processes treat the effluent before it reaches groundwater, or a restrictive layer, such as hardpan, bedrock or clay soils. These processes work best where the soil is somewhat dry, permeable, and contains plenty of oxygen for several feet below the drain field.
Warning signs of a failure:
- Odours, surfacing sewage, wet spots or lush vegetation growth in the drain field area.
- Plumbing or septic tank backups.
- Slow draining fixtures.
- Gurgling sounds in the plumbing system.
If you notice any of these signs or if you suspect your septic tank system may be having problems, call A-1 Septic Tank Service or contact Applied Science Technologists & Technicians of British Columbia (ASTTBC).
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