Symptom, likely cause, next step
| # | Symptom | Likely cause | Next step |
|---|---|---|---|
| S-01 | Several drains slow at the same time | Partial blockage in the building sewer or lateral: roots, grease, an offset or belly | Call; plan a camera inspection |
| S-02 | Toilet gurgles when a sink or tub drains | Restricted flow or venting issue downstream | Camera inspection if it keeps happening |
| S-03 | Water comes up in the shower or tub when you flush | Main line blocked past the lowest fixture | Urgent Stop water use and call |
| S-04 | Sewage smell outside near the cleanout or lawn | Cracked pipe, loose cleanout cap or leaking joint | Inspect and locate |
| S-05 | Soggy, extra-green strip over the line | Leaking lateral (or irrigation or drainage) | Camera with locating to confirm |
| S-06 | Backups during heavy rain | Rain and groundwater entering through cracks and joints | Repair or replacement after video |
| S-07 | Clogs return within months of clearing | Roots re-entering at the same joints, or a belly | Ask for video of where roots enter |
| S-08 | Backup when nobody is using water | Possible problem in the public main | Call Central San, (925) 933-0990 |
If sewage is backing up right now
- Stop using waterNo flushing, showers, dishwasher or laundry. Every gallon you send down ends up at the backup point.
- Stay clear of the sewageKeep children and pets away. Don't try to clear a live sewer line yourself.
- Check the overflow deviceIf your home has an overflow protection device near the cleanout, it may have popped to let sewage out in the yard instead of the house. That's its job (Central San).
- CallFor your own lateral, call a sewer contractor: (925) 678-6981. If backups happen while you aren't using water, Central San asks you to call (925) 933-0990 because the public main may be blocked (Central San).
Backup or slow drains right now? Call and describe what you're seeing.
What usually causes it
Central San names the usual suspects: “Most sewage overflows occur when sewer lines are blocked by roots, grease, debris, or breakage” (Central San). In older East Bay neighborhoods with big street trees, roots are the usual culprit; grease from kitchen drains makes every other defect worse.
- RootsEnter at joints and cracks
- GreaseCoats walls, narrows the pipe
- BellyHolds water and solids
- BreakageBlocks the line
Your lateral or the public main?
In Central San territory you own the lateral from the house to the main, including the part under the street (Central San). Central San maintains the main itself. If the trouble starts while nobody's using water, or neighbors have the same problem, call Central San first. Otherwise it's almost always the lateral, and the next step is a camera inspection. Then see repair options or replacement.
Details on permits and the overflow device are in the Central San guide.
Questions homeowners ask
How do I know if the problem is my sewer line or a single drain?
One slow sink or tub is usually that fixture's drain. Several fixtures slowing at once, gurgling toilets, or water coming up in the lowest drain (often a shower or tub) when you flush points to the main building sewer or lateral.
What should I do during a sewer backup?
Stop using water in the house: no flushing, showers, dishwasher or laundry. Keep people and pets away from sewage, then call. If backups happen while you aren't using water, the public main may be the problem; Central San takes service calls at (925) 933-0990 (Central San).
Why does my sewer back up when it rains?
Cracked or open-jointed laterals let rainwater and groundwater in, which can overload the line. Infiltration through cracked private laterals is the reason several East Bay cities require lateral upgrades (East Bay PSL program).
Is a soggy spot in the yard a sewer leak?
It can be, if it sits over the lateral's route and smells, or stays green and wet in dry weather. Irrigation leaks and drainage cause the same symptom, so a camera inspection with locating is the way to confirm.
Sources
- Central San: Sewer Overflow Prevention
- Central San: Overflow Protection Device
- Insurance Information Institute (Triple-I): Protect your house from sewer backups
- East Bay Private Sewer Lateral program (EBMUD region)
- Central San: Sewer Repairs (permits, cleanouts, OPDs, inspections)
Rules and programs change. Confirm current requirements with the agency before you start work.