Quick Answer:
If you smell sewage while working in the yard, start by checking the sewer cleanout and nearby ground for wet spots. Small odors can come from a loose cleanout cap or surface debris, but bubbling at the cleanout, large saturated areas, or backups in several fixtures usually mean a problem with the main sewer lateral. Photograph what you find, note dates and times, and call a licensed plumber for a camera inspection if you see bubbling, large wet zones, or persistent backups.
Why This Happens
Sewage odors near the yard most often come from one of a few issues: a loose or damaged cleanout cap, a lateral leak where the pipe between house and street is failing, clogged lines causing backflow, or tree-root intrusion that breaks joints. If multiple drains in the house show problems at once, that points toward the main line rather than a single fixture. For reading that explains linked failures, see Why multiple drains fail together. When roots are the cause, you may also find evidence described in How tree roots invade sewer lines. These topics are part of a larger set of resources under the Drain Problems cluster hub.
Step-by-Step What to Do
1. Find the sewer cleanout and inspect the cap
- Locate the cleanout—usually a capped pipe near the foundation, property line, or where the lateral leaves the house.
- Check the cap for cracks, a loose fit, displaced soil or material, or signs of fresh sewage around it.
- If the cap is wet or sewage is present, photograph it immediately and note the time and date.
2. Check the yard grade for depressions and wet spots
- Walk the yard and look for unusually soft or sunken areas, greener-than-normal grass, or standing water—these can indicate a lateral leak.
- Probe gently with a shovel edge from the surface; avoid digging deep until utilities are located.
3. Run upstream fixtures and watch the cleanout
- Have someone run water in showers, sinks, or flush toilets while you watch the cleanout for bubbling, gurgling, or backflow.
- Bubbling at the cleanout when fixtures are used is a strong sign of a blockage or failure in the main line.
4. Compare house records or municipal maps
- Check your house plans, plot plan, or municipal sewer maps to find the lateral routing and the cleanout location relative to property lines.
- This helps you understand whether the issue is on your side of the property line or in the public main.
5. Photograph evidence and log dates
- Take clear photos of the cleanout cap, any wet or sunken ground, and any bubbling or backflow you observe.
- Keep a short log with dates, times, what fixtures were in use, and weather conditions. Share this with the professional you hire.
What Not to Do
- Avoid attempting a DIY main-line replacement or major repair yourself—what looks simple can be hazardous and may violate local codes.
- Do not dig near the lateral without calling utility locates first; there may be gas, power, or other buried lines.
- Call a professional immediately when you detect sewage bubbling, large wet areas in the yard, or persistent backups across multiple fixtures—these are signs of a serious problem.
When to Call a Professional
- Call a licensed plumber if you see bubbling at the cleanout, large saturated areas in the yard, sewage pooling, or backups in several drains at once.
- Contact your municipality if the lateral routing shows the failure is on the public main or if the problem extends beyond your property.
- Ask for a camera inspection and a written report; your photos and log will help the technician diagnose the issue faster.
Safety Notes
- Sewage is a biohazard—avoid direct contact. Wear gloves and wash exposed skin thoroughly if contact occurs.
- Sewer gas can be hazardous; do not use open flames or create sparks near suspected leaks. If you smell a strong gas odor, leave the area and call professionals.
- Keep children and pets away from wet or sunken areas. Do not dig without calling 811 or your local utility-locate service first.
Common Homeowner Questions
- Why do I smell sewage only sometimes? Intermittent smells often come from a loose cleanout cap, sewer gas venting during certain wind or temperature conditions, or when fixtures are used and force air through a compromised seal.
- Can I use a shop vacuum or drain snake on the main line? Small hand snakes may clear minor clogs in household drains, but attempting to snake the main lateral yourself risks damage and is not recommended; leave main-line clearing to professionals with the right equipment.
- Will my insurance or municipality pay for repairs? Coverage depends on the source and location of the failure—municipal lines are sometimes the city’s responsibility, while lateral repairs on your property usually fall to the homeowner; check your policies and local rules.
Related Articles
If you’re troubleshooting a similar symptom, these guides may help:
For the full directory, see Drain Problems.