How does heavy rain affect septic systems?

Heavy rain can significantly impact septic systems, primarily by overloading the drain field. The drain field, which is designed to treat and disperse the effluent from the septic tank into the surrounding soil, has a limited capacity. When heavy rain occurs, the soil surrounding the drain field can become saturated with water, reducing its ability to absorb additional liquid. This saturation leads to a situation where the effluent has nowhere to go, and the system can become overwhelmed.

As a result, the septic tank may not be able to effectively process the wastewater, which can cause backups, surface seepage, or even system failure. It can also lead to pollution of nearby water sources as untreated sewage may escape from the system into the environment.

This understanding highlights the importance of designing septic systems with proper drainage and maintenance in mind, especially in areas prone to heavy rainfall. The other choices do not accurately reflect the effects of heavy rain on septic systems. For instance, heavy rain does not improve drainage or increase efficiency, nor does it have no effect at all—it is quite the opposite, as it poses serious risks to the proper functioning of septic systems.