Lateral backups
Roots in clay joints. In the County the whole lateral is yours, so we camera the full run.
ZIP 91724
Plumber for Charter Oak, CA
Charter Oak is an unincorporated community of about 9,739 people between Covina, Glendora and San Dimas. It has a Covina mailing address but no city government, so plumbing permits and public sewers here run through Los Angeles County, not the City of Covina.
Call (626) 746-1970Request service
Written and fact-checked by John, editor, MBA in marketing
Updated against City, utility and state sources
Quick answer
Charter Oak is unincorporated Los Angeles County, so plumbing permits come from LA County Public Works Building and Safety, applied for through EPIC-LA, not from Covina City Hall. The County sewer district maintains the public mains and you maintain your lateral. Your water supplier is the one named on your bill. Call (626) 746-1970 any hour.
- Status
- Unincorporated LA County
- Population
- 9,739 (2020 Census)
- Area
- 0.93 square miles
- ZIP
- 91724
Charter Oak at a glance
Charter Oak is a 0.93-square-mile census-designated place in the eastern San Gabriel Valley, with 9,739 residents and 3,231 homes in the 2020 Census.
- Status
- Unincorporated community and census-designated place in Los Angeles County
- Neighbors
- Covina to the south, Glendora to the north, San Dimas to the east
- Main road
- Arrow Highway runs through the area
- Terrain
- Mostly flat; the South Hills of Glendora form much of the northern edge
- Waterways
- The concrete-lined San Dimas Wash runs through; Walnut Creek sits in a small valley in the southeast
- Elevation
- 761 feet
- Population
- 9,739 in 2020, up from 9,310 in 2010
- Homes
- 3,231 housing units in 2020, 97.6% occupied; 63.0% of occupied homes owner-occupied
- Density
- About 10,500 people per square mile
- ZIP and area code
- 91724, area code 626
- Library
- LA County Library, Charter Oak branch
People here often say they live in Covina, and the mail agrees. Wikipedia notes that residents often call the CDP the "unincorporated part of Covina." For a plumber, though, the difference is real. Nobody at Covina City Hall can issue you a permit, inspect your water heater or clear the public sewer in your street. Those jobs belong to Los Angeles County.
We work in Charter Oak from our office in Covina, a short drive away. This page explains how County rules shape plumbing work here, who to call for what, and the patterns we see in Charter Oak homes. If your address turns out to be inside the City, our Covina 91724 page covers the City side of the same ZIP.
Where Charter Oak starts and stops
The census area called Charter Oak is smaller than the community people remember; much of historic Charter Oak now sits inside Covina and Glendora city limits.
Two maps matter here. The first is the historical one. Wikipedia describes the generally accepted old boundaries as the I-210 on the north, Valley Center Avenue on the east, Covina Hills Road on the south and Grand Avenue on the west. Those lines match the Charter Oak Unified School District.
The second is the jurisdiction map, and it is what decides your permit. After World War II, orchards gave way to subdivisions. Covina annexed areas south of Arrow Highway and Glendora annexed areas north of it. What was left unincorporated is the census area of today, 0.93 square miles.
How to check your own address
- EPIC-LA. The County's permit system warns you when an address is not in unincorporated LA County. If you get no warning, the County is your permit office.
- Covina's GIS viewer. The City says a gray parcel means County and a colored parcel with a Covina zone means City.
- Street signs. The City says Covina signs are green, often with the City logo, and blue signs suggest County territory.
- Street numbers. The City says addresses above 2999 are generally not City of Covina addresses.
How Charter Oak grew from citrus to suburb
Charter Oak started as a citrus community in the 1850s, stayed farmland longer than its neighbors because the railroad passed it by, and became a bedroom suburb in the 1960s.
- 1842
Rancho La Puente
Rancho La Puente was granted to John A. Rowland and William Workman. The Tongva people had lived in the valley for thousands of years before.
- 1850s
A citrus community
After the ranchos were subdivided, a community grew up around citrus farming. The name is tied to a large oak where, by the documented account, American soldiers camped during the Mexican-American War and thought of Connecticut's Charter Oak.
- 1887
The railroad goes north
Glendora founder George Dexter Whitcomb lobbied to route the Santa Fe line north of the South Hills. Without a rail stop, Charter Oak stayed agricultural.
- 1894
The school district
The Charter Oak School District was formed. The district says its first school opened with 24 students in a tent.
- 1922
A larger school
The school moved into a bigger mission-style building.
- After 1945
Orchards become subdivisions
Groves gave way to housing. Covina annexed land south of Arrow Highway and Glendora annexed land north of it.
- 1960s
A bedroom community
Charter Oak became a commuter suburb of Los Angeles.
- 1980
First counted as a CDP
The Census Bureau first listed Charter Oak as a census-designated place.
That history explains a lot of what we find under Charter Oak homes. The houses came in a postwar wave, many built to similar plans in the same years. Original supply pipe, drain lines and sewer laterals from that era are now 60 years old or more. And because the land stayed unincorporated, the public sewers and permit records sit with the County, not a city hall down the street.
Plumbing permits in Charter Oak come from LA County
Plumbing permits for unincorporated Charter Oak are issued by LA County Public Works Building and Safety; the County's annual report for the Covina unincorporated area lists the San Gabriel Valley office at 125 S Baldwin Ave in Arcadia.
The County's first Unincorporated Communities Annual Report for the Covina area, covering July 2023 to June 2024, lists the San Gabriel Valley Building and Safety Office, 125 S. Baldwin Ave., Arcadia 91007, phone (626) 574-0941. The 211 LA directory lists the same office as open Monday to Friday, 8 a.m. to 4:30 p.m., handling building, plumbing, electrical and mechanical permits and inspections.
Most applications start online. EPIC-LA is the County's system for applying for, tracking and paying for permits. The County's guide says the application is routed to the local Building and Safety office for your address, and that permit types labeled "Simple" or "Repair/Replacement" do not need plan review. You pay fees online once the application is accepted.
Confirm the address is unincorporated
Enter it in EPIC-LA. If it is not in unincorporated LA County, the system shows a warning and you need the city instead.
Choose the permit
Search EPIC-LA for "Plumbing" or "Residential." Types labeled "Simple" or "Repair/Replacement" skip plan review; the office tells you if plan check is needed.
Describe the work and pay
The application goes to the local Building and Safety office. Staff may contact you, then send an invoice you can pay online.
Inspection
Leave the work open until the County inspector signs off. Ask the office how to book the inspection for your permit.
| Item | City of Covina address | Unincorporated Charter Oak address |
|---|---|---|
| Office | Covina Building and Safety, 125 E College St | LA County Public Works, San Gabriel Valley office, 125 S Baldwin Ave, Arcadia |
| How you apply | In person; no online portal | Online through EPIC-LA |
| Hours | Monday to Thursday, 7 a.m. to 6 p.m., closed 1 to 2 p.m. | Monday to Friday, 8 a.m. to 4:30 p.m. (211 LA listing) |
| Water heater handout | City Handout #12 | Covina's handout does not apply; follow County requirements |
| Plan review for simple jobs | Most permits issued over the counter | "Simple" and "Repair/Replacement" types skip plan review |
One common mistake: a contractor drives to Covina City Hall with a Charter Oak address. The City cannot issue that permit. Our contractors check the jurisdiction first and pull the permit from the right agency. Our Covina plumbing permits guide covers the City process if you are on the other side of the line.
Charter Oak sewers: the County maintains the main, you maintain the lateral
In unincorporated LA County, Public Works' Consolidated Sewer Maintenance District maintains the public sewer mains, and the property owner maintains the entire lateral, including the part under the street.
LA County Public Works is direct about this. Its sewer maintenance page says laterals are "entirely owned by the private property owner they serve," and that the owner is responsible for the whole length, even under the street. County Code section 20.24.080 says laterals "shall be maintained by the owner of the property served in a safe and sanitary condition." The Consolidated Sewer Maintenance District serves the unincorporated areas of the County plus 37 cities and two contract cities.
Note the difference from the City of Covina. The City also says owners maintain the lateral to the public main. The County wording goes further and puts the section under the street on the owner too. If a camera shows a break near the curb or beyond it, that is still your repair in Charter Oak.
| Problem | Who handles it | How to reach them |
|---|---|---|
| Backup inside the house | You, through a licensed plumber | (626) 746-1970 |
| Roots or a break in your lateral, anywhere along it | You, through a licensed plumber | (626) 746-1970 |
| Sewage spilling from a manhole or the street main | LA County Public Works sewer maintenance | (800) 675-HELP right away |
| Not sure whether it is the main or your lateral | Public Works says to contact them anyway | (800) 675-HELP or the County's online Report a Problem portal |
What a County sewer notice means
The County asks owners to keep laterals flowing and free of roots and grease, to follow any sewer maintenance notice they receive, and to keep a backwater valve maintained if the house has one. If you get a notice, we can camera the line, clear it and give you a written record of what we found.
Published estimates from Angi (2026) put a sewer camera inspection at $275 to $1,800 and sewer line replacement at $1,388 to $5,323. HomeAdvisor (2025) lists main line clearing at $100 to $800. These are national ranges, not our prices. Call (626) 746-1970 for an exact quote. See our sewer lateral camera and repair page and the sewer lateral guide.
Who supplies water in Charter Oak? Check your bill
Charter Oak has no city water department, so your supplier is whichever company is named on your water bill; Golden State Water says it serves portions of Charter Oak.
Golden State Water's San Dimas service area page says the company serves residents in portions of Charter Oak, Covina, Glendora, La Verne, San Dimas and Walnut. Other parts of the area may be served by another company. The City of Covina also notes that some county pocket addresses are served by Covina Water. Neighboring suppliers on the City of Covina's purveyor list include Suburban Water Systems, Valencia Heights Water and Glendora Water. Do not guess. Read the bill.
| Measure | Average | Range |
|---|---|---|
| Total hardness | 205 mg/L, about 12 grains per gallon | 85 to 307 mg/L, 5 to 18 grains per gallon |
| Total dissolved solids | 370 mg/L | 160 to 617 mg/L |
| Sodium | 50 mg/L | 24 to 100 mg/L |
Golden State's San Dimas system blends treated groundwater from the Main San Gabriel Basin, local surface water wholesaled by Covina Valley Water Company, and imported Colorado River and State Water Project water. The report states that the system "does not have lead or galvanized service lines that require replacement," including customer-owned service lines. That does not cover pipe inside your house.
At about 12 grains per gallon, scale builds up in tank heaters, tankless heat exchangers and faucet cartridges. If you are on another supplier, ask for its annual Consumer Confidence Report. Our water suppliers and hardness guide compares the local systems, and our water softener page explains sizing.
Golden State Water contacts
- Toll-free: 1-800-999-4033
- Local: 909-394-2272
- Hearing impaired: 1-877-933-9533
Charter Oak homes and their plumbing
Charter Oak is a dense, mostly owner-occupied neighborhood of postwar houses, so the work we do here centers on aging supply pipe, laterals and water heaters.
The numbers tell the story. About 10,500 people per square mile, 3,231 homes in under a square mile, and 63% of them owner-occupied in 2020. Homeowner vacancy was 1.0%. Households averaged 3.07 people, which means a lot of showers, laundry and dishwasher loads running through older pipe.
| Part of the system | What is common in homes of this age | What it causes |
|---|---|---|
| Supply pipe | Galvanized steel in original sections; copper or PEX where remodeled | Low pressure, rusty first draw, pinhole leaks where old meets new |
| Drain pipe | Cast iron under and inside the house | Slow drains, scale, cracked sections |
| Sewer lateral | Clay pipe to the street main | Root intrusion at joints, sags, backups |
| Water heater | Tank heater in the garage | Sediment from hard water; replacement every 10 to 15 years per DOE |
| Gas connectors | Older flexible connectors at heaters and ranges | Should be checked whenever an appliance is replaced |
Larger households and water heaters
Charter Oak households averaged 3.07 people in 2020. When a heater fails, it is a good moment to ask whether the old tank size still fits the family, or whether a tankless unit makes more sense. Angi's published range for a tank water heater replacement is $600 to $2,500 (2025); tankless installs run $1,404 to $3,901 (2026). Call (626) 746-1970 for an exact quote. See water heater repair and replacement.
When a repipe makes sense
If you have had more than one leak in galvanized pipe, or pressure is weak at several fixtures, a whole-house repipe often costs less over time than chasing leaks. Angi's published range is $1,500 to $15,000. Call (626) 746-1970 for an exact quote. Our repiping page explains the process.
San Dimas Wash and what goes down the storm drain
The concrete-lined San Dimas Wash runs through Charter Oak, and street gutters feed storm drains, not the sewer, so nothing from a plumbing job should go into the street.
Storm drains and sewers are separate systems. Sewage goes to treatment. Storm drain water does not. When we drain a water heater or flush a line, the water goes to a drain inside the house or to the cleanout, never the gutter.
- Pour cooled cooking grease into a can for the trash, not the sink.
- Keep wipes out of the toilet, even ones sold as flushable.
- Never empty a water heater, spa or paint bucket into the street.
- If you see sewage in a gutter or coming from a manhole, call (800) 675-HELP right away.
Common plumbing calls in Charter Oak
Most Charter Oak calls are lateral backups, water heater replacements, galvanized pipe leaks and hard water problems.
Water heaters
Garage tanks replaced under a County permit, pulled through EPIC-LA.
Pipe leaks
Pinholes and corroded fittings in original galvanized lines. See leak detection.
Clogged kitchens
Grease and food waste in older drain lines. See drain cleaning.
Scale
Crusted aerators, running toilets and noisy heaters from hard water.
Gas lines
New lines and connectors for ranges, dryers and heaters. See our gas line plumber page.
Before you call about a hidden leak, try the EPA WaterSense meter test: read the meter, use no water for two hours, then read it again. If it moved, you have a leak. WaterSense estimates household leaks can waste more than 9,300 gallons a year. HomeAdvisor via Angi (2024) puts slab leak detection at $150 to $600. Call (626) 746-1970 for an exact quote.
Who to call in Charter Oak
For a Charter Oak home, call a plumber for anything on your side of the meter and in your lateral, your water company for the meter, and LA County Public Works for permits and the public sewer.
| Need | Who | Number |
|---|---|---|
| Leak, clog, water heater or lateral | A licensed plumber | (626) 746-1970 |
| Building or plumbing permit | LA County Public Works, San Gabriel Valley Building and Safety | (626) 574-0941 |
| Public sewer spill or blockage | LA County Public Works sewer maintenance | (800) 675-HELP |
| Leak at the meter | The water company on your bill | Golden State: 1-800-999-4033 |
| Gas smell | SoCalGas, called from outside | 1-800-427-2200; 911 if there is danger |
| Downed power line | Call 911 | 911 |
| Digging in the yard | Call 811 first | 811, at least two business days ahead |
Our who to call guide lists every local agency. Work is performed by independent CSLB-licensed C-36 plumbing contractors, with a written price before work starts and an honest arrival window. For Glendora and San Dimas, which border Charter Oak, see our nearby cities page.
Water where it shouldn't be? Call now.
A real person answers 24 hours a day. You get an honest arrival window and a written price before any work starts.
Questions Covina homeowners ask
Is Charter Oak part of Covina?
No. Charter Oak is an unincorporated community in Los Angeles County. It shares the 91724 ZIP code and a Covina mailing address, but it has no city government, so County agencies handle permits and public sewers. Some areas once called Charter Oak were annexed by Covina and Glendora.
Where do I get a plumbing permit in Charter Oak?
From LA County Public Works Building and Safety. You apply online through EPIC-LA, and the application goes to the local office. The County's Covina-area annual report lists the San Gabriel Valley office at 125 S Baldwin Ave, Arcadia. Covina City Hall cannot issue permits for unincorporated addresses.
Do I need a permit to replace a water heater in Charter Oak?
Plan on it. LA County's permit site lists repairs, replacements and plumbing work among the jobs that need a permit, and the local office confirms the details. In EPIC-LA, types marked Simple or Repair/Replacement skip plan review. We pull the County permit and leave the work open for the inspector.
Who fixes the sewer line in front of my Charter Oak house?
You do, for the lateral. LA County Public Works says the owner is responsible for the entire lateral, including the part under the street. The County maintains the public main. For a spill from a manhole or the main, call (800) 675-HELP.
Who is the water company for Charter Oak?
Check your water bill. Golden State Water says it serves portions of Charter Oak, and other parts of the area may be served by a different company. The name on the bill tells you who owns your meter and who publishes your water quality report.
How hard is the water in Charter Oak?
For Golden State Water customers, hard. Its San Dimas system reported an average of about 12 grains per gallon in 2025, with a range of 5 to 18. If another company serves you, ask for its annual report. See our hardness guide.
How big is Charter Oak?
Charter Oak covers 0.93 square miles. The 2020 Census counted 9,739 residents and 3,231 housing units. It borders Covina to the south, Glendora to the north and San Dimas to the east.
How do I know if my 91724 address is in Charter Oak or Covina?
Enter it in EPIC-LA, which warns you if the address is not unincorporated County land. Covina's GIS viewer shows County parcels in gray. The City also says blue street signs and addresses above 2999 usually mean County.
Sources
Facts on this page come from these public sources, checked November 1, 2026.
- Charter Oak, California (Wikipedia)
- Charter Oak Unified School District (Wikipedia)
- LA County Unincorporated Communities Annual Report, Covina, FY 2023-24
- 211 LA: LA County Public Works San Gabriel Valley Building and Safety Office
- EPIC-LA general permit guide
- LA County permits: how to apply
- LA County Public Works: sewer
- LA County Public Works: sewer maintenance customer information
- LA County Public Works: sewer maintenance FAQs
- City of Covina: check address jurisdiction
- City of Covina: demographics and location
- City of Covina: water purveyors servicing Covina
- City of Covina Public Works
- Golden State Water: San Dimas service area
- Golden State Water: San Dimas system water quality report
- SoCalGas emergency information
- Angi: hydro jetting and sewer camera costs
- Angi: sewer line replacement costs
- HomeAdvisor: drain and main line clearing costs
- HomeAdvisor via Angi: slab leak repair costs
- Angi: water heater installation costs
- Angi: tankless water heater costs
- Angi: cost to repipe a house
- City of Covina 2025 Consumer Confidence Report
- CSLB: Check a License
- EPA WaterSense: Fix a Leak Week