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Backwater Valves and Sewer Cleanouts in Berkeley
A backwater valve keeps sewage from coming up through low drains during a backup, and a two-way cleanout lets the line be cleared without pulling a toilet. Here’s what Berkeley requires, what’s optional, and typical install costs.
Last reviewed October 21, 2026
Quick answer: Berkeley’s sewer lateral ordinance requires a City cleanout near the curb and a private cleanout within 30 inches of the house whenever lateral testing is triggered. A backwater valve is required by the plumbing code when fixtures sit below the next upstream manhole cover, and is a smart add-on for any low fixture. Both are part of preventing backups; see drain cleaning and sewer line replacement. Call (510) 822-3070 to be connected with a licensed local plumber.
Many older Berkeley homes were built without a usable cleanout, and the lowest drain in the house (a basement laundry sink, floor drain or downstairs shower) becomes the overflow point when the line backs up. These two fittings fix different halves of that problem: the cleanout gives access to clear the line, and the backwater valve stops sewage from reaching low fixtures while it’s blocked.
Berkeley requirements
- Cleanouts (Berkeley). BMC 17.24.040 requires each lateral to have a standard City cleanout in the right-of-way or easement, and a private cleanout within 30 inches of the building or as the Berkeley Plumbing Code specifies, whichever is more restrictive. Owners install them at their own expense, with permits. They’re required when verification testing is required (sale, major remodel, repair or replacement), though you can install them any time.
- City and private sides. The City’s PSL compliance guide describes the lower lateral as running from the main to the cleanout at or near the curb and says the City maintains it; the owner maintains the upper lateral. If your lateral connects directly to a manhole, BMC 17.24.040 treats that manhole as the City cleanout and the whole lateral is private.
- Backwater valves (plumbing code). Section 710 of the Uniform Plumbing Code, the model for the California Plumbing Code, requires an approved backwater valve for fixtures below the next upstream manhole cover, installed only on the branch serving those fixtures (see this IAPMO code summary). Your contractor and the Berkeley building inspector confirm whether your house falls under it.
- No storm water in the sewer. BMC 17.24.120 requires non-sanitary connections such as roof and yard drains to be disconnected from the lateral. Rain pouring into the sewer is a big part of why lines surcharge in storms.
Backwater valve vs two-way cleanout vs overflow relief
| Device | What it does | Where it goes | Upkeep |
|---|---|---|---|
| Two-way cleanout | Access to clean or camera the lateral in both directions | On the lateral, usually within a few feet of the house | None beyond keeping the cap accessible |
| Backwater valve (mainline or branch) | Flap closes to stop sewage flowing back into the house | On the building drain or the branch serving low fixtures | Inspect and clean at least yearly |
| Overflow relief cap on the cleanout | Pops off so a backup spills outside instead of indoors | On an outdoor cleanout set below the lowest indoor drain | Keep it clear of soil and plants |
For many Berkeley houses the practical package is a two-way cleanout near the foundation, a backwater valve on the branch serving any basement fixtures, and roof drains disconnected from the sewer. Cleanouts labeled “backwater valve downstream” are required where a valve is installed, so the next plumber knows it’s there.
How installation works
- Locate and scope the line. A camera finds the lateral’s path, depth and condition so the fitting isn’t installed on failing pipe.
- Pull the permit. A plumbing permit for work on the private side; a Public Works permit if the City cleanout or anything in the right-of-way is involved.
- Excavate or open the floor. A short dig outside for a cleanout; for a backwater valve, either outside or through a basement slab.
- Install the fitting. Cut in the cleanout wye or valve body with proper couplings and an access riser.
- Test and inspect. The inspector signs off, and the access cover is finished flush.
If the camera finds cracked or root-filled pipe at the dig, it often makes sense to fix that section at the same time; see sewer line repair. For the full City test, see sewer lateral certificate.
Typical install costs
Typical reported ranges from national cost guides and the City’s current fee schedule, not quotes. Depth, concrete and access drive the price. More numbers are on our Berkeley plumbing cost guide.
| Item | Typical reported range | Source |
|---|---|---|
| Backwater valve, typical installation | $200–$1,000 | HomeServe (citing HomeGuide) |
| Backwater valve annual test | $30–$300 | HomeServe |
| Two-way sewer cleanout installation | About $2,700 | Angi |
| Cleanout installation or replacement | $1,000–$3,500 | Fixr |
| Berkeley plumbing permit base fee | $150, plus $62.50 filing fee | City fee schedule, eff. 7/1/26 |
| Berkeley lateral permit in the right-of-way | $152 per permit | City fee schedule, eff. 7/1/26 |
FAQ
Common Questions
What is a backwater valve?
A backwater valve is a check valve in the building drain with a flap that lets wastewater flow out but closes if sewage starts flowing back toward the house. It protects fixtures that sit low relative to the sewer, like a basement bathroom or laundry.
Does Berkeley require a backwater valve?
The requirement comes from the plumbing code: section 710 calls for an approved backwater valve on drainage serving fixtures located below the next upstream manhole cover. Whether your home needs one depends on fixture elevations, and the permit inspector makes the call. Berkeley’s sewer lateral ordinance separately requires cleanouts when lateral testing is triggered.
What is a two-way cleanout?
A two-way cleanout is a fitting on the sewer lateral, usually near the house, with openings facing both toward the house and toward the street. It lets a plumber clean or camera the line in either direction without pulling a toilet.
Where does Berkeley require sewer cleanouts?
BMC 17.24.040 requires a City cleanout in the public right-of-way or easement and a private cleanout within 30 inches of the building, or as the plumbing code specifies if stricter. They become mandatory when verification testing is required, for example when you sell or do a major remodel.
How much does it cost to install a backwater valve?
National cost guides report roughly $200 to $1,000 for a typical installation where the line is easy to reach. Retrofitting a main-line valve on an older house with digging, concrete or a deep line costs more; get a written quote after the line is located.
How often does a backwater valve need maintenance?
Have it checked at least once a year, and ideally before the rainy season. Debris or grease can keep the flap from sealing, and a valve stuck closed can back water up into the house.
Is a backwater valve the same as a backflow preventer?
No. A backwater valve protects the house from sewage coming back up the drain. A backflow preventer protects the drinking water supply and is installed on the water line, not the sewer.
Keep reading
Related Services
Drain cleaning
Clear a backed-up main line.
Sewer line replacement
New lateral with cleanouts built in.
Sewer lateral certificate
When Berkeley requires testing.
Want to stop the next backup?
Call (510) 822-3070. You’ll be connected with an independent, licensed plumber who can check your line and quote a cleanout or backwater valve.
Sources checked October 21, 2026: BMC 17.24.040 (cleanouts) · BMC 17.24.120 · Berkeley PSL Compliance Guide · City of Berkeley Fee Schedule (eff. 7/1/26) · IAPMO – UPC 710 backwater valves · HomeServe – backwater valve cost · Angi – sewer cost data · Fixr – sewer line cleaning cost
Prices on this page are typical reported ranges from national cost guides and the City’s published fees, not quotes; Berkeley labor often lands at the upper end. Your price comes in writing after the job is seen. Berkeley Plumbing Services connects callers with independent, licensed plumbing contractors. You can check any California contractor’s license at cslb.ca.gov.