Climate Change -Episodic Storms and Your Septic

Virginia Tech recently did a webinar addressing thestrategies for preparing your septic system for storms and flooding. The climate is changing. We’re not going to be able to stop it, so we have to be prepared for the future that is going to arrive. There have always been great storms, but they are forecast to become more frequent and intense.

According to Phillip Brown, professor at Virginia Tech the 1 degree Celsius increase in temperature that we’ve experienced since the industrial age has produced a 7% increase in the moisture in the atmosphere. More moisture brings more intense rainstorms. In addition, the likelihood of flooding has increased. Sea level is 8-9 inches higher than it was in 1880 and rising faster than in the past. In 2022 sea level was 4 inches higher than it was in 1993. Higher sea level allows storms to push further inland. More intense storms bring more frequent flooding to inland areas.

Locally (here in Prince William County Virginia), rainfall averages approximately 44 inches per year, but varies from year to year.  Climate forecasts are for our region to get wetter with more intense rainstorms and droughts to get more severe. (ICPRB). The relationship between climate change and flooding is complex. Shoreline flooding is the result of land subsidence, sea level rise, building in the flood plain and storm surge. The most well-established connection between climate change and inland flooding is that more warming leads to more intense rainfall, which in turn increases flood severity in the inland areas. Recent data shows that inland flooding in Prince William County has increased. We can assume that the flood is coming.

According to Dr. Brown, septic failure can contaminate groundwater impacting your well and your neighbors, and bring diseases into the home. Failed septic systems can release excessive nutrients into waterway resulting in algal blooms and fish kills. Also, failed septic systems can result in sewage backing up into your house. The best way to make sure your septic system survives a flood or excessive rain event is to maintain the system. First and foremost, is to pump your septic tank every 2-3 years. I do not care what the regulations say. PUMP IT. As a tank fills with solids over the years, the retention time falls and the open space that usually exists in a tank is smaller. You need the about 100- 200 gallons of open space a regularly pumped tank has.

Make sure that the drain field has good grass and ground cover. Finally, make sure that the manhole covers are sound and secure. This is to prevent anyone from falling in and keeping some of the flood waters out.

Just before a storm, make sure any drainage ditches are clear and the water drains away from the house and the septic system. Many septic systems do not operate on gravity and need pumps to move the effluent from the septic tank to the drain field. Alternative systems may have many other components like blowers, filters that require electricity to operate. If you experience flooding cut the breakers and stop using anything but minimal water. With a low flow toilet, you have days of flushing in the available space in your septic tank. That, however, means that you cannot let any other water down the drain until the system is up and running again.

After flood waters recede septic systems should not be used immediately. Drain fields will not work until underground water has receded and the soil has dried out. Whenever the water table is high or your septic drain field has been flooded, there is a risk that sewage will back up into your home due to the water pressure from the flooded drain field. Though septic lines may have broken during the flood it is more likely that the lines were just submerged.

The only way to prevent a flooded system from backing up is to relieve pressure on the system by using it less- so do not allow your tank to pump or drain to the drain field until the soils dry out. Basically, there is nothing you can do but wait, do not use the system if the soil is saturated and flooded. The wastewater will not be treated and will become a source of pollution, if it does not back up into your house, it will bubble up into your yard. Conserve water as much as possible while the system restores itself and the water table fails.

Do not return to your home until flood waters have receded. If there was significant flooding in your yard, water will have flooded into your septic tank through the top. The tops of septic tanks are not water tight even with good manhole covers. Flood waters entering the septic tank will have lifted the floating crust of fats and grease in the septic tank. Some of this scum may have floated and/or partially plugged the outlet tee. If the septic system backs up into the house check the tank first for outlet blockage. Remember, that septic tanks can be dangerous, methane from the bacterial digestion of waste and lack of oxygen can overwhelm you. Hire someone with the right tools to clear your outlet tee.

Do not pump out the septic tank while the soil is still saturated or right before a storm hits. Pumping out a tank that is in saturated soil (or soon to be saturated soil) may cause it to “pop out” of the ground. (Likewise, recently installed systems may “pop out” of the ground more readily than older systems because the soil has not had enough time to settle and compact.) If the tank pops out, it will pull and damage all the piping and connections. The system will have to be rebuilt.

Call a septic service company (not just a tank pumping company) and schedule an appointment in a few days. Do not use the septic system for a few days (I know) have the service company clear any outlet blockage, or blockage to the drain field, check pumps and valves and partially pump down the tank if your soils are not dry enough or fully pump the tank if the soil has drained enough. The available volume in the tank will give you several days of plumbing use if you conserve water to allow your drain field to recover. Go easy the septic system operates on the principals of settling, bacterial digestion, and soil filtration all gentle and slow natural processes that have been battered by the storm.

If your yard is unlikely to flood, even with catastrophic amounts of rain. (My house and septic sit about 20 feet above the rest of the yard.) You still should conserve water until your septic system dries out.