Comptche water and wastewater due diligence begins with a physical question: how do water and waste move through this particular property? A well, storage tanks and house connections can occupy different parts of wooded acreage, while an onsite wastewater system has its own layout and record history. The buyer needs to connect those components with documents, rights and current specialist findings.
This article expands the infrastructure discussion in our Comptche overview. It uses an actual county-filed property diagram to demonstrate document reading and current county routes to organize follow-up. No private system has been inspected for this draft. The public example establishes a research method, without certifying the illustrated property’s approvals, performance or present condition.
Read an actual diagram as a starting point
The county’s property diagram for AG 2019-0175, marked revised October 2023, separately labels a well, storage tanks, the pipe supplying houses and a septic area. It is a useful local example because the water arrangement extends beyond one visible fixture. Each labeled component creates a distinct evidence question.
For a current purchase, begin by matching the diagram’s project and parcel identifiers with the actual property file. Ask who prepared it, why it was filed and whether later revisions exist. A drawing can describe an applicant’s arrangement without being an approved construction plan or a record of completed work. Keep the document’s original purpose attached to its interpretation.
Trace the depicted sequence from source through storage to the residences. In a property investigation, ask whether that sequence remains accurate and which structures are actually connected. A seller may refer to a single water system even when the equipment and conveyance cross several areas. The buyer needs to understand the whole arrangement before choosing the scope of inspection.
The septic label requires a separate file inquiry. A marked area is useful for locating the question but does not establish the type, capacity, permitted configuration or current condition of the installation. Obtain the relevant approval history and specialist review. Do not expand the diagram into an assurance that every connected use has been evaluated.
Retrieve the current county file and identify its limits
The county’s current Environmental Health permits page supplies well and onsite-wastewater resources, including non-standard inspection material and an owner well-completion request. The county has migrated its website, leaving some older references inaccessible. Ask staff for the actual parcel file and missing documents rather than assuming the available webpage is a complete archive.
Keep Environmental Health records separate from the general construction search. The county permit portal describes electronic-history limits associated with its automated system. Use a combined chronology to relate residence work, system approvals and later changes. A building record should not be treated as proof that every water or wastewater issue was resolved.
Obtain the original layout, completion evidence, repairs, maintenance and current reports where available. Record which document addresses construction, which addresses operation and which describes present observations. If an older file conflicts with the current arrangement, identify the discrepancy for the relevant reviewer. A neat packet is useful only if its contents actually refer to the same system.
Separate source performance, storage and treatment
Ask the qualified water professional to distinguish the source’s observed performance from the operation of storage and pressure equipment. A substantial storage installation is not equivalent to an unlimited source. Likewise, a source assessment may not evaluate every pipe, tank or household fixture. The report should explain the components and conditions included in the investigation.
For a system relying on gravity between storage and houses, identify the actual layout and operating requirements with the reviewer. Do not infer adequate household delivery merely from a pipe shown on a plan. Ask what observations or measurements support the intended use, and whether changes in equipment or demand require additional evaluation.
For water-quality testing, preserve the source identity, sampling point, collection date, methods and tests actually performed. Results before treatment and at a household tap can answer different questions. Have the appropriate professional define and interpret a plan suited to the actual arrangement. This guide does not prescribe a universal test panel or interpret health results.
Collect treatment equipment records and recent maintenance where applicable. Ask whether the current assessment includes treatment performance and what continuing service is required. A service invoice, well construction report and laboratory result serve different purposes. Keeping them distinct prevents a favorable document about one component from becoming a broad claim about the entire water system.
Original Comptche diagram-to-evidence packet
Public example: county-filed AG 2019-0175 diagram, revised October 2023. Source routes checked October 25, 2026. No current condition or approval is certified.
| Feature shown in public example | What the diagram contributes | Property evidence still required | Appropriate question |
|---|---|---|---|
| Well | Identifies a depicted source location | Actual source identity, completion history and scoped current assessment | Does this source supply the present residence and intended demand? |
| Separate storage tanks | Shows storage as a distinct component | Condition, maintenance, ownership and operating review | What do storage and source each contribute? |
| Pipe to houses | Depicts conveyance beyond the well site | Actual connected structures, route, rights and current operation | Are depicted connections current and documented? |
| Septic area | Locates a separate wastewater inquiry | Actual system file, approved layout and specialist inspection | What configuration and use are documented? |
| Project/parcel labels | Provides a reference for file retrieval | Later revisions and county confirmation | Which document is operative for today’s arrangement? |
| Future buyer use | Not established by this diagram | Accurate proposed scope and relevant agency response | Does the proposed change require further system review? |
Investigate rights and maintenance beyond the equipment
Locate each component in relation to the legal property interests being acquired. If the well, pipe or access for maintenance crosses other land, obtain the relevant recorded documents and legal review. Ownership of a residence does not necessarily explain every right needed to operate and repair its supply. A diagram’s line is not itself an easement.
For shared infrastructure, obtain the agreement and actual operating history. Identify users, cost allocation, decision procedures and how a new owner becomes involved. Ask about outstanding repair proposals and disputes. A cooperative history may be encouraging while still leaving uncertainty about who can authorize work or enter a neighboring parcel.
Ask the specialist to identify maintenance access needed for the proposed work. Equipment can be reachable for routine observation while requiring different arrangements for replacement. Before relying on a repair quote, confirm that permissions, route and scope have been considered. Otherwise the price may address an operation the buyer cannot yet arrange.
Review wastewater independently of the water supply
Match the wastewater file with the residence and other connected structures. Compare approved layout and documented use with the current configuration. A detached building may create a question about plumbing or occupancy even where it appears secondary in marketing. Give the inspector the actual property use rather than asking only whether the tank looks serviceable.
Separate pumping from a scoped assessment of the installation. An invoice documents a service event, while current condition, component access, permitted configuration and proposed capacity require their own evidence. Ask what the inspection covers and what remains unknown. Preserve exclusions so the buyer can decide whether additional investigation is needed.
The North Coast Regional Water Board’s onsite wastewater program page identifies local management-plan routes, including Mendocino County. That establishes regulatory context, not a certificate for an individual system. Ask the county which current requirements apply to the actual installation or proposed change.
Use local landscape context without treating it as a test
Where the record contains several drawings, create a revision list before the inspection. Identify whether each shows existing conditions, proposed work or a later change. Ask the county which approved drawing is relevant. That prevents an inspector and buyer from discussing different arrangements while using the same informal system name.
The federal Comptche appellation rule describes contrasting valley and slope soils. That regional discussion provides useful questions for a site professional about drainage and proposed system locations. It does not establish the soil or wastewater suitability at a selected point on the property. A regional description cannot replace actual site evaluation.
If additional occupancy or an improvement matters to the purchase, submit the same proposal to the relevant system and planning reviewers. Distinguish the evidence supporting current use from the work needed to evaluate a new configuration. A satisfactory report for the seller’s arrangement should not silently become approval for the buyer’s expansion.
Use our buying process guide to coordinate deadlines and the Mendocino County overview for context. The completed Comptche packet should let a buyer follow source, storage, household connections and wastewater to their own documents and current findings, with every unresolved right or condition clearly identified.
