Before you add an ADU, it's worth knowing whether the sewer line it will depend on is ready for the extra flow.
Written byNew Pro Plumbing·Reviewed byMiguel Lopez, Owner & Licensed Plumber, New Pro Plumbing (CSLB #974600)·Last reviewedSeptember 2026 · 8 min readQuick Answer
An accessory dwelling unit usually adds bathrooms and a kitchen that drain into your existing sewer lateral. A camera inspection before construction shows whether that line can handle it; if it's failing, trenchless renewal can be done before or alongside the ADU build. In Mar Vista, ADUs are going up behind many older homes whose laterals were laid for a single household decades ago.
Most ADUs tie into the property's existing sewer system. That means the lateral that has served one household for decades will now carry the drains from a second kitchen, bathroom, and laundry. If that lateral is original clay or cast iron with root damage or cracks, the added flow can turn a slow line into a recurring backup. This page is part of our complete guide to trenchless sewer repair in Mar Vista.
Trenchless Sewer for ADUs: ADU sewer planning is the inspection and, if needed, trenchless renewal of an existing sewer lateral before an accessory dwelling unit's plumbing connects to it.
The right time to find out is before construction. A camera assessment during planning shows the line's condition and route, which helps your designer place the ADU's connection. If renewal is needed, doing it trenchless before the build avoids digging through new hardscape later.
In Mar Vista, ADUs are going up behind many older homes whose laterals were laid for a single household decades ago. Many Mar Vista ADU projects tie into original clay laterals that were never designed for two households.
We record and locate the existing lateral early in design.
Footage and route information go to your designer or contractor.
Lining or bursting brings the lateral up to the task before the build.
We plan the tie-in point with your ADU plumbing layout.
Camera first, always. Every recommendation starts with a recorded inspection you can watch yourself, and a flat-rate price you approve before we start.
ADUs have become a common addition behind Mar Vista homes, and most of them tie into a lateral that was laid for one household seventy or more years ago. We've seen owners finish a beautiful backyard unit only to discover that the original clay lateral beneath the new patio can't keep up. The better sequence is to camera the line during design. If it's sound, your plans proceed with confidence. If it's failing, we can renew it trenchless before construction, coordinated with your ADU contractor and permitted through LADBS alongside the rest of the project.
From the flats near Centinela to the hill streets near the Santa Monica border, Mar Vista homes tend to share one thing underground: an aging lateral that has rarely been replaced. Many laterals here have been patched once or twice over the years, so a single run can mix clay, cast iron, and newer plastic. We pull the City permit, book the inspection, and leave the property as clean as we found it.
Not sure what your line needs? We camera it first, then quote a flat rate.
Get a Free Quote| Detail | Mar Vista |
|---|---|
| Area | Mar Vista, CA 90066 |
| Jurisdiction | City of Los Angeles |
| Permits | LADBS (City of Los Angeles) |
| Typical access | A cleanout or two small access pits |
| First step | Camera inspection with a copy of the recording |
| Pricing | Flat-rate, in writing, before work starts |
| Availability | 24/7, including weekends and holidays |
| License | CSLB #974600, insured |
| Languages | English and Spanish |
Mar Vista sits in City of LA limits, which means LADBS handles the permit and the inspection for sewer lateral work. LA Sanitation splits the lateral into an upper section, from the house to the property line, and a lower section, from the property line to the main, and the owner is responsible for maintaining both. We'll tell you up front if your job needs anything beyond a standard plumbing permit.
Example scenario below is illustrative, based on common situations we see. Details vary by property; not a specific customer.
A Mar Vista owner planning a backyard ADU asks whether the existing sewer can handle a second unit.
Our camera shows root-damaged clay under the future patio; we line the lateral before construction begins.
The ADU connects to a renewed line, and the new patio never has to be cut for sewer work.
When you call New Pro from Mar Vista, a real person answers, and a licensed plumber handles the work, not a subcontractor you've never met. Our trucks carry the camera, locating, jetting, and repair equipment most sewer jobs need. We keep the camera recording and job records, so you have a history if you ever need it.
Also serving neighborhoods near Mar Vista: Palms, Del Rey, Culver City, Westdale. See all Westside service areas.
The Bottom Line
An ADU adds real load to your sewer lateral. Inspect it during planning, and if it needs renewal, do it trenchless before the new construction goes in.
Not always. Many ADUs connect to the existing lateral. Whether that works depends on the lateral’s condition and capacity, which a camera inspection shows. ADU projects often stress the original sewer with new fixtures, and City of LA plan check will look at the existing lateral’s capacity and condition. See LADBS permits for the ADU sewer requirements.
During design, before plumbing plans are finalized. It’s much easier to adjust plans than to fix a line under a finished ADU. The right time to camera your lateral for an ADU is before the framing goes up. Doing it later can mean opening finished landscaping and hardscape to reach the pipe.
Yes. We’ll share footage and route information and coordinate the tie-in with your contractor. For a lateral with any real age, lining or bursting during ADU construction avoids a repeat sewer call in year three or five of the new unit. See our trenchless repair page.
The connection point is planned with the liner in mind. If the ADU line joins the lateral, we plan that junction as part of the job. We coordinate with your ADU contractor and, if needed, the plans examiner so the sewer scope is documented in the permit set from day one.
Yes, during design. It’s much easier to renew the lateral before the ADU and new patio go in than to cut through them later. For an ADU in Mar Vista, LADBS plan check looks at existing lateral capacity; camera before framing goes up. See LADBS permits.
This page was written by the New Pro Plumbing content team and reviewed for technical accuracy by Miguel Lopez, owner and California-licensed plumber (CSLB #974600). Agency rules are summarized from the official sources above; programs and requirements can change, so confirm current details with the agency. Nothing here is a quote. We confirm scope and pricing in writing before any work begins.
What’s new: September 2026, first publication.
Before you add an ADU, it's worth knowing whether the sewer line it will depend on is ready for the extra flow.
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