Saturation ranking
Where septic & water well services is most and least saturated in California
Every California market with sourced Septic & Well data, ranked on how much provision it already has. Counties are measured per 10,000 residents. Cities are measured as a share of the businesses in the same ZIP codes, because a city’s establishment counts cover its ZIP codes rather than its city limits and cannot be divided by its municipal population. Neither measure says anything about revenue or profitability, and a crowded market is not automatically a bad one: it is also where the most businesses come up for sale.
- Statewide establishments
- 2,711
- 2023 County Business Patterns
- State median density
- 1.0
- Per 10,000 residents, counties
- Counties ranked
- 48
- of 50 with data
- Cities ranked
- 111
- of 201 with data
Most saturated counties for septic & well
48 of 50 counties with sourced data qualify for this ranking. Markets with fewer than 5 establishments are excluded at both levels, because a single opening or closing would move them enough to dominate the list. Counties under 2,000 residents are also excluded, where a per-capita figure is arithmetically true and analytically useless.
| # | County | Establishments | Per 10k | Vs state median | Reading |
|---|---|---|---|---|---|
| 1 | Plumas County18,583 residents | 8 | 4.3 | +328% | Densely served |
| 2 | Calaveras County46,605 residents | 20 | 4.3 | +326% | Densely served |
| 3 | Mariposa County16,918 residents | 6 | 3.5 | +252% | Densely served |
| 4 | Glenn County28,141 residents | 8 | 2.8 | +182% | Densely served |
| 5 | Tuolumne County53,160 residents | 15 | 2.8 | +180% | Densely served |
| 6 | Nevada County101,911 residents | 28 | 2.7 | +173% | Densely served |
| 7 | Tehama County64,665 residents | 17 | 2.6 | +161% | Densely served |
| 8 | Sonoma County486,444 residents | 114 | 2.3 | +133% | Densely served |
| 9 | El Dorado County192,323 residents | 44 | 2.3 | +127% | Densely served |
| 10 | Siskiyou County42,013 residents | 9 | 2.1 | +113% | Densely served |
| 11 | Napa County132,949 residents | 27 | 2.0 | +102% | Densely served |
| 12 | San Benito County70,082 residents | 13 | 1.9 | +84% | Densely served |
| 13 | San Luis Obispo County282,367 residents | 52 | 1.8 | +83% | Densely served |
| 14 | Placer County442,081 residents | 80 | 1.8 | +80% | Densely served |
| 15 | Shasta County181,648 residents | 32 | 1.8 | +75% | Densely served |
State median for this industry: 1.0 establishments per 10,000 residents. A high figure means more provision per resident, not more demand.
Least saturated counties for septic & well
The same 48 counties, read from the bottom of the ordering upward. Thin provision is worth checking against the neighbouring counties before treating it as an opening.
| # | County | Establishments | Per 10k | Vs state median | Reading |
|---|---|---|---|---|---|
| 1 | San Francisco County826,079 residents | 25 | 0.3 | -70% | Thinly served |
| 2 | Los Angeles County9,694,934 residents | 365 | 0.4 | -63% | Thinly served |
| 3 | Santa Clara County1,914,391 residents | 78 | 0.4 | -60% | Thinly served |
| 4 | Solano County455,376 residents | 21 | 0.5 | -54% | Thinly served |
| 5 | Yolo County224,410 residents | 12 | 0.5 | -47% | Thinly served |
| 6 | Tulare County485,146 residents | 26 | 0.5 | -47% | Thinly served |
| 7 | Stanislaus County557,719 residents | 30 | 0.5 | -47% | Thinly served |
| 8 | Kern County927,068 residents | 50 | 0.5 | -46% | Thinly served |
| 9 | Sacramento County1,618,460 residents | 88 | 0.5 | -46% | Thinly served |
| 10 | Alameda County1,636,630 residents | 89 | 0.5 | -46% | Thinly served |
| 11 | Imperial County181,411 residents | 10 | 0.6 | -45% | Thinly served |
| 12 | San Mateo County743,568 residents | 42 | 0.6 | -44% | Thinly served |
| 13 | San Joaquin County823,815 residents | 49 | 0.6 | -41% | Thinly served |
| 14 | Monterey County433,729 residents | 26 | 0.6 | -40% | Thinly served |
| 15 | Merced County297,260 residents | 18 | 0.6 | -40% | Below average |
State median for this industry: 1.0 establishments per 10,000 residents. A low figure can mean a genuine gap, or a market served from the next county over.
Most saturated cities for septic & well
111 of 201 cities with sourced data qualify for this ranking. Markets with fewer than 5 establishments are excluded at both levels, because a single opening or closing would move them enough to dominate the list. Cities with fewer than 500 businesses in total are also excluded, because on a base that small the industry’s share moves on rounding.
| # | City | Establishments | Share of local | Vs state share | Reading |
|---|---|---|---|---|---|
| 1 | Jurupa Valley1,066 businesses in total | 17 | 1.59% | +747% | Densely served |
| 2 | WildomarRiverside, 577 businesses in total | 9 | 1.56% | +728% | Densely served |
| 3 | PlacervilleEl Dorado, 974 businesses in total | 14 | 1.44% | +663% | Densely served |
| 4 | Santa PaulaVentura, 523 businesses in total | 7 | 1.34% | +611% | Densely served |
| 5 | NorcoRiverside, 840 businesses in total | 9 | 1.07% | +469% | Densely served |
| 6 | Lake ElsinoreRiverside, 1,327 businesses in total | 14 | 1.06% | +460% | Densely served |
| 7 | TruckeeNevada, 1,148 businesses in total | 12 | 1.05% | +455% | Densely served |
| 8 | OrovilleButte, 774 businesses in total | 8 | 1.03% | +449% | Densely served |
| 9 | PerrisRiverside, 1,263 businesses in total | 13 | 1.03% | +447% | Densely served |
| 10 | OakdaleStanislaus, 702 businesses in total | 7 | 1.00% | +430% | Densely served |
| 11 | SonomaSonoma, 1,218 businesses in total | 12 | 0.99% | +423% | Densely served |
| 12 | HealdsburgSonoma, 764 businesses in total | 7 | 0.92% | +387% | Densely served |
| 13 | RichmondContra Costa, 1,549 businesses in total | 14 | 0.90% | +380% | Densely served |
| 14 | HollisterSan Benito, 1,025 businesses in total | 9 | 0.88% | +366% | Densely served |
| 15 | AtascaderoSan Luis Obispo, 918 businesses in total | 8 | 0.87% | +363% | Densely served |
| 16 | SanteeSan Diego, 1,273 businesses in total | 11 | 0.86% | +359% | Densely served |
| 17 | Los BanosMerced, 581 businesses in total | 5 | 0.86% | +357% | Densely served |
| 18 | MenifeeRiverside, 1,513 businesses in total | 13 | 0.86% | +356% | Densely served |
| 19 | SonoraTuolumne, 818 businesses in total | 7 | 0.86% | +354% | Densely served |
| 20 | San FernandoLos Angeles, 848 businesses in total | 7 | 0.83% | +338% | Densely served |
| 21 | Red BluffTehama, 607 businesses in total | 5 | 0.82% | +337% | Densely served |
| 22 | SebastopolSonoma, 987 businesses in total | 8 | 0.81% | +330% | Densely served |
| 23 | PetalumaSonoma, 2,420 businesses in total | 19 | 0.79% | +317% | Densely served |
| 24 | Arroyo GrandeSan Luis Obispo, 896 businesses in total | 7 | 0.78% | +315% | Densely served |
| 25 | HesperiaSan Bernardino, 1,542 businesses in total | 11 | 0.71% | +279% | Densely served |
Statewide, 0.19% of California businesses are in this industry. A higher local share means the industry takes up more of the local business base than it does statewide.
City figures are aggregated over the ZIP codes the Postal Service assigns to each place, which do not follow municipal boundaries. That is why the comparison here is a share of the businesses in those same ZIP codes rather than a figure per resident: both sides then cover the same ground, so a city that loses establishments to a separately named ZIP loses its denominator with them.
Most underserved cities for septic & well
The bottom of the same ordering. These are the California cities carrying the least septic & well provision per resident among those that clear both floors.
| # | City | Establishments | Share of local | Vs state share | Reading |
|---|---|---|---|---|---|
| 1 | San FranciscoSan Francisco, 33,575 businesses in total | 15 | 0.04% | -76% | Thinly served |
| 2 | San DiegoSan Diego, 42,106 businesses in total | 19 | 0.05% | -76% | Thinly served |
| 3 | San JoseSanta Clara, 21,501 businesses in total | 26 | 0.12% | -36% | Below average |
| 4 | Palo AltoSanta Clara, 3,843 businesses in total | 5 | 0.13% | -31% | Below average |
| 5 | Santa ClaraSanta Clara, 4,587 businesses in total | 6 | 0.13% | -31% | Below average |
| 6 | SacramentoSacramento, 19,687 businesses in total | 26 | 0.13% | -30% | Below average |
| 7 | Thousand OaksVentura, 3,759 businesses in total | 5 | 0.13% | -29% | Below average |
| 8 | Santa AnaOrange, 8,181 businesses in total | 11 | 0.13% | -29% | Below average |
| 9 | CarlsbadSan Diego, 5,494 businesses in total | 8 | 0.15% | -23% | Below average |
| 10 | Long BeachLos Angeles, 9,885 businesses in total | 15 | 0.15% | -19% | Below average |
| 11 | OrangeOrange, 5,761 businesses in total | 9 | 0.16% | -17% | Below average |
| 12 | OxnardVentura, 3,760 businesses in total | 6 | 0.16% | -15% | Below average |
| 13 | Chula VistaSan Diego, 4,885 businesses in total | 8 | 0.16% | -13% | Typical |
| 14 | Costa MesaOrange, 5,397 businesses in total | 9 | 0.17% | -11% | Typical |
| 15 | FullertonOrange, 4,049 businesses in total | 7 | 0.17% | -8% | Typical |
| 16 | OaklandAlameda, 10,328 businesses in total | 18 | 0.17% | -7% | Typical |
| 17 | PleasantonAlameda, 3,345 businesses in total | 6 | 0.18% | -5% | Typical |
| 18 | Redwood CitySan Mateo, 3,279 businesses in total | 6 | 0.18% | -3% | Typical |
| 19 | ModestoStanislaus, 5,412 businesses in total | 10 | 0.18% | -2% | Typical |
| 20 | Rancho CucamongaSan Bernardino, 5,340 businesses in total | 10 | 0.19% | -1% | Typical |
| 21 | Santa BarbaraSanta Barbara, 5,868 businesses in total | 11 | 0.19% | -0% | Typical |
| 22 | BreaOrange, 2,531 businesses in total | 5 | 0.20% | +5% | Typical |
| 23 | GardenaLos Angeles, 3,007 businesses in total | 6 | 0.20% | +6% | Typical |
| 24 | San MarcosSan Diego, 2,711 businesses in total | 6 | 0.22% | +18% | Above average |
| 25 | Buena ParkOrange, 2,195 businesses in total | 5 | 0.23% | +21% | Above average |
Statewide, 0.19% of California businesses are in this industry. A lower local share can mean a genuine gap, or a market served from the next town over.
How to read these rankings
- Both measures are supply measures. They say nothing about how much each business earns, how large it is, or how much demand comes from outside the market.
- The two levels are not directly comparable to each other. A county figure is establishments per resident; a city figure is this industry’s share of the local business base against the statewide share. Compare counties to counties and cities to cities.
- A thinly served market can be a genuine gap or a market already served from a neighbouring town. The individual market pages list the nearest comparable places for exactly this check.
- A densely served market means competition, but it is also where the largest pool of existing businesses sits, and therefore where the most owners reach retirement each year.
- Counties are the more stable measure. City figures rest on ZIP code geography, which the Postal Service redraws as it pleases, so a city can gain or lose a ZIP between years.
Full septic & well data for California/All industry rankings/Methodology
Sources
- U.S. Census Bureau, 2023 County Business Patterns. Establishment counts, employment and annual payroll by NAICS. Retrieved 2026-09-08.
- U.S. Bureau of Labor Statistics, Quarterly Census of Employment and Wages (2026Q1). Quarterly establishment counts and employment for employers covered by unemployment insurance. Retrieved 2026-09-08.
- U.S. Census Bureau, 2023 ZIP Code Business Patterns. Establishment counts by ZIP code and NAICS, aggregated over the ZIP codes assigned to each city, including the all-industry totals used as the local business base. Retrieved 2026-09-10.