A cesspool is a buried pit that lets raw sewage seep straight into the soil with no tank to separate solids from liquid first, and California has not allowed anyone to build a new one since the state's onsite wastewater policy took effect in 2012. If a cesspool turns up on your property in Tehama, Butte, or Shasta County, whether that's during a sale, a remodel, or because the yard is backing up, the county is going to require a cesspool to septic conversion, not a patch job. That catches a lot of rural property owners off guard, because a cesspool that's worked without complaint for forty years doesn't look like a problem until someone with a clipboard says otherwise.
Walberg, Inc. has installed and replaced septic systems across Tehama, Butte, and Shasta counties since 1999, and cesspool conversions come up more than you'd think on older ranch parcels and homes built before the 1970s. Here's what actually separates the two systems, what forces a conversion, and what the process looks like once it starts.
What makes a cesspool different from a septic tank
A septic tank system does two jobs in sequence. The tank holds wastewater long enough for solids to settle out and scum to float, so only clarified liquid effluent leaves the tank. That effluent then disperses through a drain field, where soil bacteria finish breaking it down before it reaches groundwater.
A cesspool skips the tank. Raw sewage, solids and all, goes straight into a lined or unlined pit and seeps out through the pit walls and bottom. There's no settling stage and no real treatment. It works, in the sense that the water eventually goes somewhere, right up until the pit clogs with solids or the surrounding soil can't absorb any more.
| Cesspool | Septic tank system | |
|---|---|---|
| Solids handling | None. Solids enter the soil with the liquid | Solids settle in the tank and stay out of the drain field |
| Treatment before it hits soil | None | Bacterial digestion in the tank plus soil treatment in the drain field |
| Legal to install new in California | No, prohibited statewide since 2012 | Yes, under county LAMP permitting |
| Typical age if found on a property | Usually pre-1970s construction | Any age, including systems installed last year |
| Groundwater and well risk | Higher, especially on smaller lots or near a well | Lower when sized and sited correctly |
Why the state stopped allowing them
The State Water Resources Control Board's Onsite Wastewater Treatment System Policy doesn't authorize cesspools at all, because a system with no tank sends untreated pathogens and nutrients directly into the ground. On a rural lot with a well thirty or forty feet from the pit, that's not a hypothetical risk. It's the exact failure mode the policy exists to stop.
The state policy sets the floor. Counties administer it locally through their own Local Agency Management Programs, and Tehama, Butte, and Shasta counties each handle discovered cesspools a little differently.
What Tehama, Butte, and Shasta counties actually require
None of the three counties will let you keep a cesspool once it's identified, but the trigger that forces the issue isn't identical everywhere.
| County | How it's handled |
|---|---|
| Shasta | Cesspools haven't been approved since the county's Sewage Disposal Standards took effect in the mid-1970s. Any cesspool found in use has to be destroyed and replaced with a compliant onsite wastewater treatment system. |
| Tehama | Cesspools of any kind or size aren't authorized under the county's OWTS Policy, full stop, regardless of how the county finds out about it. |
| Butte | County code requires that a repair to an onsite wastewater system bring the whole system into conformance with current ordinance requirements. A repair call on a cesspool becomes a conversion, not a fix. |
The Shasta County Environmental Health OWTS program and each county's Environmental Health department are the offices that issue the abandonment and new system permits, and they're the ones who make the call on your specific parcel.
When you actually get forced into a conversion
Most cesspools don't get discovered because an owner went looking. They come up during:
A pump truck visit where the technician can't find a tank, because there isn't one. A real estate transaction, where a lender or a county point-of-sale inspection flags the system before closing can happen. A remodel or ADU permit application that touches plumbing, since adding fixture units usually means the county reviews your entire wastewater system, not just the new work. A slow drain or backup call that turns into a site visit and an unwelcome discovery.
We've seen this play out on a ranch outside Corning where the owner was converting a barn into a rental unit, and on a property near Anderson where the seller found out mid-escrow that the system serving a 1960s farmhouse was never a septic tank to begin with. Neither owner had done anything wrong. The system predated the rules that now govern it.
How the conversion actually works
Converting a cesspool isn't cheaper or simpler than installing a brand-new septic system, and it helps to go in expecting that.
- Locate and probe the existing pit to confirm depth, condition, and how close it sits to a well, a property line, or a structure.
- Run a percolation test on the proposed new drain field location. This can't be the same footprint as the old cesspool, because the soil around a cesspool has been absorbing untreated effluent for years or decades and won't perc reliably for a new system.
- Get an engineered design sized to your fixture count and lot conditions, submitted to the county for permit review.
- Abandon the old cesspool under permit: pump it out, break or collapse the structure if required, and fill it per the county's specified method.
- Install the new septic tank and drain field.
- Pass county inspection and get final sign-off before anyone starts using the new system.
One honest note here: some national guidance describes converting a cesspool into a smaller "seepage pit" system as a cheaper shortcut. That's not really an option in Tehama, Butte, or Shasta County. All three counties require a complete system with a septic tank ahead of the drain field, not just a bigger, better-built version of the pit you're replacing. If a contractor tells you otherwise, get a second opinion before you sign anything.
What it costs
A cesspool conversion is functionally a new septic system installation, since the tank, distribution components, and drain field all have to go in from scratch, plus the abandonment work on the old pit. Cost depends on lot size, soil conditions, drain field placement, and how the old cesspool needs to be decommissioned, and those variables move enough from site to site that a real number only comes from walking the property. Request a free estimate and we'll give you a straight answer after we've seen the ground.
Common Questions
How do I know if I have a cesspool instead of a septic tank?
Check your county Environmental Health records first, since most rural parcels have a permit history on file even for old systems. If there's no septic permit on record, or the file shows a "seepage pit" or nothing at all, that's a red flag. A licensed contractor or septic pumper can also confirm it during a site visit by locating (or failing to locate) a tank.
Can I just repair my cesspool instead of converting it?
In Butte County specifically, no. Any repair permit application requires bringing the system into full compliance, which means conversion. Tehama and Shasta don't authorize cesspools at all once identified, so a repair permit on a cesspool typically triggers the same outcome.
What happens if I don't convert an illegal cesspool?
The county can require abandonment and conversion once it's aware of the system, and that awareness often arrives at the worst possible time: mid-sale, mid-remodel, or after a failure that creates a public health complaint. Waiting doesn't remove the requirement. It just removes your control over the timeline.
Does converting a cesspool cost the same as a new septic system?
It's close, and sometimes more, since the old cesspool has to be properly abandoned in addition to installing the new tank and drain field. There's no discount version of this project in Northern California's LAMP counties.
Will my homeowners insurance help pay for this?
Generally no. Standard homeowners policies don't cover the cost of replacing a wastewater system due to age or a compliance issue. This is a capital project you'll be funding directly, which is exactly why getting an accurate estimate before you're under a closing deadline matters.
The bottom line
If you own an older property in Tehama, Butte, or Shasta County and you've never confirmed in writing whether your onsite wastewater system is a septic tank or something older, do it on your own timeline, not the county's. Pull the permit history, get a site visit, and find out now instead of during escrow or after a backup ruins a weekend. Walberg, Inc. handles both the abandonment and the new system installation as one project, so you're not coordinating two contractors to get from cesspool to compliant. Reach us at (530) 824-0773 or request a free estimate to get a straight read on your property.