A Bethel Island ownership budget needs to connect each structure and service with the party responsible for paying and maintaining it. The house, dock, access route, water supply, wastewater connection and shared facilities should not disappear into a single estimated maintenance percentage. A useful comparison explains both the amount and the obligation behind it.
This guide develops the cost questions in the Bethel Island guide through two actual public sewer-charge entries and an original operating-and-reserve worksheet. Research was checked October 26, 2026. The public entries are not complete private bills, inspected homes or permissioned ownership budgets. No insurance quote, dock-repair estimate or private association financial package was supplied, so no all-in annual ownership total is claimed.
Begin with what each property actually includes
List the dwelling, accessory accommodation, outbuildings and waterfront components represented in the purchase. Add the land-side route to each component and the documents establishing use. Separate an owned improvement from a separately contracted boating service. Then identify which bills the owner pays directly and which costs are collected through an association or another arrangement.
This first step prevents an unfair comparison between a house with more services inside one payment and another with separate invoices. A due that includes a utility is not simply an extra charge on top of the same owner’s utility bill. Conversely, a low recurring payment may leave the owner responsible for work excluded from the shared budget.
For each line, record its source, period, collecting party and whether the amount is recurring, a one-time payment or a reserve contribution chosen by the buyer. Do not use an unknown as zero. An empty cost field should name the document or quote needed and the person responsible for obtaining it.
A local sewer comparison with actual public numbers
Ironhouse Sanitary District’s public fiscal 2026–27 sewer charge roll lists 1398 Taylor Road, APN 028-080-035, as a single-family residence with $967.64. It lists 1388 Taylor Road, APN 028-080-034, as a single-family residence with an ADU with $1,381.90. These are specific published charge-roll entries, not descriptions of current private condition or proof that the accounts have been paid.
The difference between those two published annual entries is $414.26. This establishes a difference in one public cost component. It does not establish the total added cost of accessory accommodation, the private plumbing configuration, the accommodation’s legal status or whether either property is available. Those questions require their own records rather than an interpretation of the sewer category.
The District’s current rate page reports Board approval on May 19, 2026, with the new structure effective July 1. It also explains that individual classes can change differently from the overall increase. Do not apply a single headline percentage to every candidate account or assume a charge from a previous fiscal year is still the correct input.
There is a small but useful source distinction. The March 2026 final rate study shows $967.65 for the single-family annual rate, one cent above the public single-family roll entry used here. The worksheet preserves the actual published roll amount. Confirm the candidate’s current account and bill with the District rather than silently changing either source to make them agree.
Keep this comparison in its proper category. It is a two-parcel public sewer illustration, not two complete household budgets. An additional dwelling can prompt other service, condition and insurance questions that the charge roll does not answer. For a real purchase, match the current configuration to the provider’s classification and request clarification of any discrepancy.
Original annual operating and capital-reserve worksheet
| Input | 1398 Taylor Road | 1388 Taylor Road | Evidence and treatment |
|---|---|---|---|
| Parcel identifier | 028-080-035 | 028-080-034 | Ironhouse FY2026–27 public charge roll |
| Published sewer category | Single-family residence | Single-family residence with an ADU | Provider’s roll category; not an independent legal-use finding. |
| Published annual sewer amount | $967.64 | $1,381.90 | Original subtraction: $1,381.90 − $967.64 = $414.26. |
| Water, energy and other services | Not supplied | Not supplied | Obtain actual provider, billing period and current account evidence. |
| Property tax and direct assessments | Not supplied | Not supplied | Use buyer-specific tax estimate and actual parcel charges; count included sewer once. |
| Insurance and shared charges | Not supplied | Not supplied | Actual quote, governing documents, dues and approved assessments. |
| Owner maintenance and capital reserve | Not supplied | Not supplied | For each owner-maintained component: verified work scope, quote, timing and access. |
Annual operating subtotal = verified annual recurring charges, counting each payment once. A simple capital planning contribution = estimated owner-funded project amount ÷ documented planning years remaining; state the quote, timing assumptions and any existing dedicated funds separately. This formula is a planning device, not a local contractor quote, useful-life finding or funding guarantee. Full ownership totals cannot be calculated from the supplied evidence.
Verify the water provider instead of borrowing another tariff
Diablo Water District’s consolidation outreach list, updated November 2024, identifies multiple local water systems. Its potential-consolidation page, updated September 2025, describes feasibility assistance for possible consolidation. Neither record establishes that every Bethel Island home now receives the same water service or pays the same tariff.
Obtain the candidate’s actual water account and ask who supplies and bills the service. If a mutual company, shared arrangement or private system is involved, request the relevant payment and maintenance documents. Do not turn a planned connection, outreach meeting or grant discussion into a completed service upgrade in the budget.
Use a complete available billing year to understand the seller’s pattern, then distinguish that history from the buyer’s intended use. Record occupancy, irrigation and any unusual event before annualizing one bill. A period of vacancy can make a household’s consumption look low without reducing fixed charges or establishing what another household will spend.
For energy, identify which actual equipment serves the residence, additional accommodation and any waterfront components. Ask for the relevant account and any equipment agreement that creates an ongoing payment. Keep a possible future installation in a project scenario rather than treating it as an existing feature with verified operating costs.
Separate public district charges from private maintenance
The BIMID annex to the 2024 County hazard mitigation plan describes public funding and levee and drainage responsibilities. It is historical planning information. It does not establish the current 2026–27 assessment for a particular parcel or the private responsibility for maintaining a home’s deck, dock or access route.
Request the actual parcel tax statement and identify each direct charge by agency and purpose. If a district amount is already included in the annual tax total, mark it rather than adding it again. Keep public district charges, private association payments and the owner’s own maintenance reserve separate even when all three relate broadly to the waterfront setting.
Contra Costa County’s new-owner guidance explains that a supplemental bill is additional to the regular bill and goes to the owner even with an impound account. Budget buyer-specific acquisition timing separately from recurring ownership. A seller’s existing tax amount is supporting history, not a complete estimate of a new buyer’s future obligation.
For a shared arrangement, request current dues, approved special assessments and the documents assigning maintenance. Establish what happens when significant work is needed and which party can authorize it. A manager’s general service description cannot substitute for the candidate’s applicable documents and current financial evidence.
Budget the dock by scope, access and permission
A local scope example appears in the County’s February 2026 issued-permit report: a dock shade canopy at 6004 Windsweep Road. The entry illustrates that waterfront components can have their own work records. Its permit valuation is not an available repair quote, a forecast of recurring maintenance or evidence that the work was completed.
Ask the specialist to identify the actual component, condition limitation and proposed work before seeking a price. Record whether access from land or water, lifting, temporary arrangements or restoration is included. Obtain the required agency and private approvals for the defined scope. Two numbers cannot be meaningfully compared if one contractor has priced only surface work and another has included a broader structural investigation.
Separate routine care from replacement planning and any immediate correction recommended by the professionals. Use a reserve schedule tied to the documented component and chosen planning horizon. If the condition or timing is uncertain, show alternative scenarios with their assumptions rather than assigning a universal annual percentage to every waterfront home.
If the buyer instead plans to use a marina, request the actual current agreement and quote. Include the relevant storage, launching or berth charges in that separate scenario. A seller’s arrangement does not automatically transfer with a house, and an advertised service price does not establish availability for the buyer’s vessel.
Complete the comparison with fresh private evidence
Obtain address-specific insurance terms and identify the components and perils covered. Keep the quote date, limits, deductibles, exclusions and conditions alongside its premium. A property-level maintenance plan and a coverage proposal answer different questions; one cannot supply missing prices or condition findings for the other.
Present verified recurring amounts, acquisition cash, capital planning and unresolved inputs separately. Review the full comparison with the appropriate professionals before relying on a total. The financing guide and Contra Costa County guide provide broader context while the actual Bethel Island parcel, service and ownership documents determine the budget.
