The short answer
Why Septic Tanks Float
Floodwater saturates the soil around your septic tank, making the ground heavy and less able to hold the tank in place. At the same time, the tank itself may be empty or partially empty, so it becomes buoyant. The upward pressure from groundwater can literally lift the tank, sometimes several inches or more.
This movement can damage the inlet and outlet pipes, crack the tank walls, and break the seal that keeps wastewater contained. Even a small shift can cause lasting problems. You might not notice the movement right away, especially if the water is still high. Checking the area around the tank after floodwaters recede is a good first step.
Signs Your Tank Has Moved
Look for obvious clues like a lid that is no longer flush with the ground, cracks in the tank visible at the surface, or soil that appears pushed up around the edges. You may also see a dip or hump in the yard where the tank sits. If the tank has shifted, the ground above it often looks disturbed.
Inside your home, watch for slow drains, gurgling sounds, or sewage backing up into sinks or toilets. These can indicate that the tank's pipes have separated or shifted. If you notice any of these signs, limit water use immediately to reduce the load on the system. Do not open the tank yourself, as it may be unstable.
- Lid is tilted or raised above the ground
- Cracks or gaps appear around the tank's access point
- Soil is mounded or sunken near the tank location
- Drains are slow or sewage backs up into the home
- You hear gurgling from pipes after flushing
- The ground feels soft or spongy over the tank
What to Do Right Away
Stop using water in your home as soon as you suspect the tank has floated. This means no flushing, showers, or laundry. Continued use adds pressure to a damaged system and can push wastewater into the surrounding soil, which is a health hazard. If you can, have everyone in the household use a portable toilet until the system is checked.
Keep children and pets away from the tank area. Floodwater can carry contaminants, and a shifted tank may expose raw sewage. Do not attempt to push the tank back into place or drain it yourself. The tank could be fragile, and the soil around it may be unstable. Call a local water damage pro to assess the situation.
How Pros Handle a Floating Tank
A water damage pro will first inspect the tank and the surrounding soil to see how far it has moved. They may use a camera to check the internal pipes for cracks or disconnections. Depending on the condition, the work usually involves pumping out the tank, draining it safely, and then repositioning it with heavy equipment.
The tank may need to be anchored to a concrete base or have soil compacted around it to prevent future movement. Pipes that have separated will be reconnected, and any cracks sealed. This is not a do-it-yourself job. A pro has the tools and knowledge to handle the weight and the wastewater safely.
Preventing Future Floating
If you live in an area prone to flooding, you can take steps to reduce the risk. Keep the tank as full as possible during flood season, since a full tank is less buoyant. You can also have a pro install a permanent anchor system, such as concrete deadmen or straps, that hold the tank down.
Check your property's drainage to ensure water flows away from the tank. Adding soil or redirecting downspouts can help. After any flood, have the system inspected even if you see no obvious signs. Early detection of a small shift can save you from a costly repair later. If you live in Layton, keep a record of your tank's location and any past repairs.
Water damage does not wait
Phones are answered 24/7 for Layton and nearby communities.
Call Now (801) 383-0232Frequently asked questions
Will my septic tank always float in a flood?
No, not always. Floating depends on the tank being partially empty, the soil being heavily saturated, and the tank not being anchored. A full tank is less likely to float because the weight of the wastewater holds it down. If you are unsure, a pro can assess your specific situation.
Can a floating septic tank fix itself?
No, a floating tank will not settle back into place on its own. Once the soil dries, the tank may settle unevenly, which can cause pipes to crack or separate. Professional help is needed to reposition the tank and repair any damage. Waiting can lead to more extensive problems.
Is it safe to use my plumbing after a flood?
It is safest to avoid using plumbing until a pro inspects the system. If the tank has shifted, wastewater may not flow properly and could back up into your home or leak into the ground. Using water increases the risk of contamination. Have a pro check the tank before returning to normal use.