Soggy Ground Over the Drain Field
Wet, spongy ground or standing water over a drain field: how to tell rain and a high water table from a failing field, and what to do.
Rain, groundwater or effluent?
Soggy ground after a storm is normal for a day or two. Ground that stays wet in a dry week, smells of sewage or shows green stripes over the trenches is effluent coming up. In low areas, the seasonal water table can also rise into the field from below, which looks like failure but needs a different fix.
Where this is most common
Wet soils and heavy rain. NOAA normals put Smithfield, North Carolina at 49.37 inches of rain a year and Brooksville, Florida at 51.94 inches. Florida requires a new drain field to sit 24 inches above the wet-season water table (Rule 62-6.006, F.A.C.), which is why low Florida lots often get a raised field. See the Texas, North Carolina and Florida state guides for local soils.
Quick checks
- Note whether the wet area follows the trench lines or covers a low spot that drains the whole yard.
- Check gutters and downspouts; roof water aimed at the field can drown it.
- Look for a leaking toilet or faucet; constant flow overloads a field.
- Space out laundry and long showers for a week and watch whether it dries.
Fixes, from cheapest
Redirect roof and surface water, fix leaks, and have the tank pumped (Angi: $292 to $565). A clogged line can be jetted (HomeGuide: $200 to $1,400). If the soil has sealed or the field sits in groundwater, the fix is a new field, often raised or a mound where the water table is high; HomeGuide puts a mound at $10,000 to $20,000. Read repair vs replacement before you sign.
Sources
NOAA NCEI U.S. Climate Normals 1991–2020; Rule 62-6.006, F.A.C.; EPA, How to Care for Your Septic System; HomeGuide, Drain/Leach Field Replacement Cost (Dec 22, 2025, cited as text); Angi, Septic Tank Pumping Cost (Jul 9, 2026, cited as text).
Prices are published US ranges from the sources listed on each page; anything we calculated ourselves is labeled as an estimate. Get at least three written, itemized local quotes. Run the estimator to build your own range.