Heavy rains can cause significant stress on your septic or aerobic system, especially if your system is older or hasn’t been maintained in a while. Following a major rainstorm, you may notice the following problems:
- Wastewater backups
- Untreated wastewater outside in the drain field
- Drains that gurgle or empty slowly
- Reduced effluent quality
- Erosion that exposes or damages septic or aerobic system components
- Groundwater contamination
- Temporary system shutdowns (aerobic systems)
- More frequent alarms (aerobic systems)
Even after the heavy rains are over, your septic or aerobic system may be vulnerable to continued rains, as it will take some time for them to recover from a high-volume influx of runoff.
How Does Heavy Rainfall Affect a Septic System?
Septic and aerobic systems each respond to heavy rains a bit differently, but in both cases, extreme weather is a major stressor. And in the case of septic systems, here’s what may happen in the wake of a heavy rainstorm:
- Wastewater backups – Heavy rains can oversaturate the drain field that effluent passes into following treatment. If this happens, it will be difficult for your septic system to keep up. In severe cases, wastewater may back up into the home if it can’t drain into the septic tank. Wastewater backups may occur wherever there’s a drain in the home, including sinks, tubs and toilets.
Heavy rain can also cause groundwater levels to rise, which places additional pressure on the septic tank and underground septic system components. If this pressure is too intense, it can cause sewage backflows into the building. If this occurs, it is considered a health hazard to anyone who is exposed. - Untreated wastewater in the drain field – Drain field saturation and increased septic tank pressure can also cause wastewater to pool outside in the yard. If you notice unpleasant odors, standing water or vegetation overgrowth, it could be a sign that wastewater is saturating your property.
- Slower drainage speeds and gurgling drains – As rainwater collects in the yard and causes groundwater levels to rise, the increased pressure around the tank will force wastewater back through the system. This will manifest in the building in several ways, including slower drainage, gurgling drains (due to trapped air) and sewage odors inside the building. These issues may be present until pressures around the septic tank are alleviated.
- Reduced effluent quality – Heavy rains can affect the bacterial composition inside the septic system, reducing its ability to treat effluent as it enters the septic tank. This may lead to a reduction in effluent quality, as waste passes through without as much exposure to beneficial bacteria. Eventually, the lower quality effluent may be ejected into the drain field or clog the outlet pipe.
- Soil erosion and septic component damage – Heavy rains may erode the soils around the septic system, which can destabilize the septic tank or its components. There is a greater risk of this occurring on sloped properties. Erosion can expose septic system components (increasing the risk of damage), crush or shear septic pipes or lines and adversely affect the drain field’s ability to absorb treated effluent.
- Groundwater contamination – If effluent isn’t adequately treated before it leaves the septic system, which may be the case if bacteria levels are affected by groundwater pressure, it can lead to poor quality effluent entering the drain field. In high enough concentrations, this may contaminate groundwater and cause health or environmental issues that must be resolved.
How Do Heavy Rains Affect an Aerobic Septic System?
Heavy rains can also adversely affect aerobic wastewater systems, though in slightly different ways. Some examples include:
- Wastewater backups, pooling wastewater or poor effluent quality – Heavy rains can also cause these issues in aerobic systems, even though they tend to be more efficient at treating waste. If heavy rains saturate the drain field, it can cause wastewater to pool on the field’s surface, due to poor absorption. If any drainage elements are flooded, this can also affect effluent quality or cause wastewater backups into the building.
- Temporary system shutdowns – Aerobic systems rely on several electronic components to function, including the pump, timers, air compressors and control components. Heavy rains may damage these components if they are exposed to moisture. Further, heavy rains may raise water levels and, consequently, cause the air pump to short cycle and drop in efficiency.
- More frequent alarms – Aerobic septic systems are designed with float switches and alarms that may be affected by heavy rains. This can lead to frequent high-water and pump failure alarms. While these aren’t necessarily a sign that there’s a problem or failure with the system, it may be annoying, and it indicates that your aerobic system may not be able to handle normal wastewater volumes.
Your Septic System Expert Can Prepare Your Septic or Aerobic System for Heavy Rains
In wet climates like Houston, where heavy rains are common, it’s important to safeguard your septic system from potential flooding. This is especially true if your septic or aerobic system hasn’t been maintained or inspected recently. And if your system is overwhelmed, it can cause backups, slow draining, a saturated drain field, septic system damage, system shutdowns or groundwater contamination.
If you’re unsure whether your septic or aerobic system is ready for heavy rains, contact your septic system expert and schedule an inspection.
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