Connecticut Septic B100a Rules, Private Well Testing, Radon and Buried Oil Tanks — CT Home Field Guide
Updated October 2026
A Connecticut house can have attractive finishes and still carry expensive underground problems. For homes with private septic systems, wells or historical oil heat, organize specialized inspections while contract protections remain available. A standard home inspection rarely answers every question a lender, health district or future renovation will raise.
Understand what B100a review does
Connecticut Public Health Code Section 19-13-B100a addresses building additions, conversions and changes of use involving properties served by onsite sewage disposal systems. It is not a universal certificate proving that an existing septic system is sound whenever a home changes hands.
Adding bedrooms, finishing space or changing a property's use can require local health review. The review may examine existing system capacity, site conditions and the ability to provide suitable sewage disposal. Ask the local health department or district what the proposed project requires before budgeting an expansion.
For a purchase, collect:
- Septic permits, approved plans and available as-built drawings.
- Pumping and repair records, plus a qualified inspection report.
- The approved bedroom count and documentation for later additions.
- Information about reserve areas, setbacks and site limitations.
A recent pumping receipt is not a substitute for a condition assessment. For rental properties, compare system capacity with the legal unit configuration in the multifamily financing guide.
Test water and radon deliberately
Private-well testing should address lender requirements and local health guidance, with additional testing based on site history. Bacteria, nitrate, arsenic, uranium and other contaminants may warrant attention depending on the location and recommended testing panel. Water yield and water quality are separate questions.
Radon in indoor air and radon in water also require different tests. Arrange testing under the specified conditions, then obtain mitigation estimates when results justify action. Do not assume a lender's minimum testing requirement answers every household health concern.
For FHA transactions, property acceptability and required repairs are distinct from the county loan ceiling. Review agency resources through HUD FHA Mortgage Limits and confirm the lender's documentation requirements.
Resolve tanks and financing before closing
Ask about both active and abandoned underground oil tanks. Obtain removal, closure and sampling records where available. An unexplained fill pipe or historical oil heating system deserves investigation; tank removal and contaminated-soil cleanup are different expenses.
Connecticut's closing attorney can coordinate contractual repair obligations and required documentation. Use the closing cost estimator to budget specialized inspections separately from lender fees. The Consumer Financial Protection Bureau helps distinguish mortgage closing costs from the broader costs of becoming a homeowner. Resolve required repairs before assuming a lender will permit an escrow holdback.
Compare Current Mortgage Rates
Compare current APRs, points, fees, and estimated monthly payments from participating lenders below.
Loan Program Comparison: 2026 Benchmarks
Connecticut Septic B100a Rules, Private Well Testing, Radon and Buried Oil Tanks — Choose a mortgage by comparing eligibility, upfront cash and total monthly costs, not the advertised rate alone. Conventional, FHA, VA and USDA serve different borrowers. Confirm county limits, taxes, insurance and lender requirements before comparing personalized Loan Estimates for your household.
Historical 2025 one-unit comparison: conforming $832,750; FHA floor $541,287. County and unit-count limits can differ.
| Loan program | Down payment / equity | 2026 one-unit baseline | Costs and page-specific comparison |
|---|---|---|---|
| Conventional | 3%–5% subject to eligibility | $832,750 | PMI generally below 20% down |
| FHA | 3.5% at 580+; 10% at 500–579 | $541,287 floor | 1.75% upfront MIP; 0.55% annual for >95% LTV, base loan ≤$726,200, term >15 years |
| VA | 0% for eligible borrowers | No VA limit with full entitlement | No monthly PMI; funding fee unless exempt |
| USDA | 0% for eligible borrowers | Income, address and repayment eligibility | Guarantee and annual fees; confirm current schedule |
| Jumbo | Lender-specific cash and reserves | Above applicable conforming limit | Lender-specific pricing and insurance |
| Home Equity / Refinance | Equity and underwriting dependent | Property and lender dependent | Compare closing costs, term and break-even |
Sources: FHFA limits; HUD FHA limits.
Editorial Methodology & Primary Sources
Verification date: Not recorded; check the primary source and lender timestamp before relying on an estimate.
Rate comparisons use participating lender feeds, not a whole-market survey or guaranteed offers. Freddie Mac PMMS is a market benchmark, not a personalized quote. Calculator models rely on published regulatory formulas and disclosed assumptions rather than fabricated first-person loan testing.
Monthly principal and interest use the amortization formula P × r / (1 − (1 + r)−n), where r is the monthly note rate and n is the number of payments; at zero interest use P / n. PITI adds monthly property taxes and homeowners insurance; PMI is separate. APR includes applicable finance charges under Regulation Z and is not the note rate used for payments. Compare lender Loan Estimates for actual APR and fees.
- Consumer Financial Protection Bureau (CFPB) — Loan Estimates, APR and borrower disclosures; Regulation Z.
- U.S. Department of Housing and Urban Development (HUD / FHA) — FHA program guidance.
- U.S. Department of Veterans Affairs (VA) — VA loan eligibility and benefits.
- Freddie Mac Primary Mortgage Market Survey (PMMS) — published rate benchmarks.
- U.S. Census state tax collections — state property tax benchmarks; confirm parcel-specific assessments and exemptions with the state revenue department and local assessor.
- Connecticut Housing Finance Authority — state housing finance and property tax authority.
- Connecticut Office of Policy and Management — state housing finance and property tax authority.
The payment snapshot uses illustrative annual taxes of 1% of home price, $1,200 insurance and 0.5% PMI below 20% down, not verified local quotes. Other calculators disclose their inputs and assumptions. Published guidance and lender feeds may change independently; confirm current program rules, taxes and offers before a decision.