Most of your septic system is sealed and unaffected by heavy rain, but one part — the drain field — is not, and a heavy rain can definitely affect it. If it has been raining particularly hard and there's a pond forming in your drain field, you may experience the symptoms of a blocked septic system. The best course of action is to reduce water consumption in the house until things dry out.
Symptoms of a Flooded Septic System
You don't need anyone to tell you when it has been raining hard, but you may not recognize the symptoms of a flooded system at first. As the soil in the drain field becomes saturated, septic water can't soak in, and it may rise to the surface and create an odor. As the condition worsens, water backs up into the tank, and if you have a transfer pump, the pump may start running continuously. Eventually, because the water has nowhere else to go, it ends up in your plumbing. You'll notice slow draining, poor toilet flushing, and, in extreme circumstances, overflow from floor and shower drains and even from toilets on the ground floor.
How to Handle Septic Flooding
If you notice puddles and septic tank odor during a heavy rain, reduce water in the drain field by rerouting any roof drainage that goes there. Temporarily shut off the power to the transfer pump in the tank, if you have one. This not only saves electricity, it prevents the pump from burning out. You should reduce water usage in the house to what's absolutely essential, because every time water goes down the drain, it adds to the excess in the tank. Take short showers or use a no-rinse body wash, flush toilets as seldom as possible, and avoid using the dishwasher and washing machine.
To get your septic system professionally inspected, contact Morse Engineering and Construction.