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Most homeowners do not realize that steady rain, either as seen with a severe rainstorm or even just long periods of sustained light rainfall can dramatically affect their septic systems. Significant rainfall can quickly flood the ground around the soil absorption area (drainfield) leaving it saturated and making it impossible for water to flow out of your septic system. With nowhere to go, the water eventually travels backward through the plumbing system and back into drains and toilets and into your home.  The best way to prevent harm to your septic system is to take all the necessary precautionary measures ahead of time and to stay informed.


Septic System Basics

Most septic system owners have a vague understanding of how their systems work. A quick review of the components and functions of your system will provide a clearer understanding of how weather affects it.

  • Tank

Basic septic systems have two main parts: a septic tank and an absorption field. A septic tank is a buried, water-tight container usually made of concrete, fiberglass, or polyethylene. The breakdown of sewage begins in the tank. First, wastewater from the household flows into the tank through a drainage pipe. Then the tank holds the wastewater from the household long enough for the solids to settle to the bottom of the tank. During this process, oil and grease in the water float to the top and form a scum on the surface. Finally, the liquid part of the wastewater (effluent) exits the tank and drains into the absorption field.

  • Drainfield

The second part of the system is the drainfield. The drain field is a shallow, covered, excavation made in unsaturated soil. This soil absorbs and percolates the wastewater, allowing harmful substances to be broken down naturally.


How Different Weather Conditions Affect Your Septic System

If your home has a septic system, it is vital to keep it well-maintained and running smoothly to avoid costly and inconvenient issues. Septic systems perform a variety of critical functions, including the effective disposal of human waste and treating waste water so it makes its way back to the environment as clean groundwater.



Heavy rainfall can lead to the drain field consuming excessive amounts of water, which cause it to become over-saturated. An over-saturated drain field will become clogged and will not be able to treat the water. This causes the drain field to flood as the water has nowhere to go.

A flooded septic system can also lead to untreated waste leaking into the ground. This can be very hazardous to your health and the environment.

  • Flooding

During excessive rainfall, the drain field can become flooded or overworked. When the drain field consumes too much water, there is nowhere for it to go and the drain field floods. When the drain field becomes over-saturated, it becomes clogged and unable to treat the water.

  • Backups

One of the results of a flooded septic system is pipe clogging and backups. When the drain field is flooded, the water has nowhere to go. It will then begin traveling back up your pipes and into drains and toilets. You might see excess water in your drains or you could experience difficulty draining. If your area has experienced heavy rainfall and your drains seem clogged, a flooded septic system could be the cause.

  • Sewage Leakage

Another effect of a flooded septic system is the leakage of untreated effluent into the ground. When your drain field is flooded, it will become overwhelmed and will not be able to treat the effluent. Untreated sewage will then leak into the groundwater, which can be damaging to the environment and to your health.  When sewage leaks into the ground, the water can become contaminated and cause serious consequences.



Extremely cold weather can cause different components or even the entire septic system to freeze up. Thankfully, you can easily cover your septic tank with a blanket or insulating material to keep it warm during the colder months.

  • Frozen Tank Components

When frost or snow gets deep into the components of your septic system, it can freeze these components, or even the entire system. When these components are frozen, it will slow down the metabolism of the anaerobic bacteria inside the septic tank, which hinders its ability to break down waste.  Vegetation around your tank can help shield it from the cold as well. Running your water and using your septic system every day can also help reduce the risk of freezing.

  • Improperly Functioning Pipes

When your pipes have leaks or clogs, they can often lead to improper drainage. Leaks during the cold can also cause water to freeze, which will damage your septic system further. Clogs can cause wastewater to accumulate in your pipes, with cold causing the wastewater to freeze over. In order to avoid these issues, fix leaky pipes before the cold sets in and be sure to address and clogs or leaks as soon as you notice them to avoid allowing these problems to get more severe.

  • Compacted Snow and Soil

When you drive over snow, it can compact the snow above your tank or drain field. These actions combined with cold temperatures can make the soil above your tank and in your drain field compact and dense. When the soil above your septic tank compacts, wastewater will not be properly filtered and drained and it will be less effective at insulating your tank, leading to a frozen system. To avoid these issues, be sure to aerate your soil before the cold weather sets in and avoid driving over these parts of your lawn.



Windstorms, heavy rain and thunderstorms can damage your septic system not only due to the downpour, but because of the accompanying strong winds as well.

  • Debris in Your Septic Tank

Severe storms such as thunderstorms and tornadoes can cause damage to your septic system not only because of rainfall, but because of strong winds as well. After these storms, it is fairly common to end up with trees or debris in your plumbing or septic system. While storm damage is somewhat unavoidable, the risk of damage can be minimized by trimming loose branches of trees in your yard, and keeping the yard debris free.


Before, During and After the Storm


  • The best way to handle a heavy rainfall is to make sure your septic system is in good shape before the rains roll in. Septic problems can be worse if your tank needs to be pumped or the system has not been properly maintained.
  • Provide an alternate route for runoff water to keep it away from the drainfield so the surrounding soils do not get extra soggy. Keep rain gutters clear of debris and make sure all gutters drain away from the drainfield area.
  • Do not drive any heavy equipment or other vehicles that could compact the soil over the drainfield. Compacted soils can reduce the soil absorption field’s ability to treat wastewater. Plant only grass above the drainfield.


  • If your drainfield is flooded or if you begin to notice that drains are not draining quickly, toilets flush slowly or make strange sounds, your septic system is under significant stress. The only way to relieve pressure on the system is by using it less. If possible, reduce or eliminate water going down the drains until the drainfield dries out.
  • Conserve water to minimize the load on your septic system. Do not flush the toilet unless absolutely necessary. Reduce the amount and length of showers if you can. Avoid running the dishwasher and put off doing laundry until the system has been restored.


  • If you suspect any damage to your septic system or if the water over the drainfield does not recede after the rain stops, have your septic tank professionally inspected and serviced.
  • If silt and debris have gotten into your septic tank, have the system pumped as soon as possible. Wait until the water has receded and the area is no longer saturated before opening the tank.


Call West Coast Sanitation Today!

Septic systems are responsible for disposing of human waste, treating wastewater, and ensuring the water used in your home makes its way back into the environment as clean groundwater. Most homeowners understand the importance of a properly functioning septic system, but they might not be aware of how the weather can impact their septic system.

At West Coast Sanitation, we know that you don’t have time to deal with septic problems. If you think that your system has reached capacity, please give us a call at (951) 780-5922 right away. We have professionals ready to answer your questions and get your system working properly again. We have professionals ready to answer your questions and get your system working properly again.