Jurisdiction here is settled
The Census Bureau records Plainview as a census designated place, GEOID 3658442, whose polygon lies within Oyster Bay town and shares no boundary line with another town in the county (TIGERweb, place layer and county subdivisions). One town therefore holds the building records for anything inside that outline.
Applications are obtainable from the Town of Oyster Bay Building Division at 74 Audrey Ave in Oyster Bay and at its annex in Town Hall South, 977 Hicksville Rd in Massapequa. The town writes that the division "also issues certificates of occupancy and regulates the maximum occupancy in places of public assembly," which answers the question a buyer usually has about an addition: who signed off on it. Telephone (516) 624-6200, extension 1.
The outline is a statistical one, drawn for reporting rather than by a municipality, and postal delivery does not follow it. An address that reads Plainview is not evidence of which government holds the permit file; the county's Land Records Viewer settles that per parcel.
Gas leads the heating table, which usually implies a conversion
Of 8,748 occupied units, utility gas heats 5,251, fuel oil or kerosene 2,765, electricity 472 and bottled or LP gas 98 (B25040). In a stock built when oil heat was the default, a gas majority is largely the residue of conversions, and a converted house is where an unused tank gets left behind.
Those records sit with the county, not Albany: the state's rule summary puts petroleum bulk storage here under county administration, "pursuant to delegation from DEC" (petroleum tank regulations). The giveaways cost nothing to notice — two short pipes at the siding, disconnected tubing near the chimney base, a strip of lawn that sinks after rain — and what to request is the abandonment or removal record. Things to raise, rather than findings about this place.
What the year-built table supports, and what it does not
Housing units number 9,078, the median year of construction 1957, itself good to one year (B25035). The 1950s account for 5,769, to within 466; the 1960s for 1,395, to within 281; and 449, to within 132, date from 2000 through 2009 (B25034). The older counts deserve care rather than emphasis: 198 from the 1940s and 136 from 1939 or earlier carry error margins of 104 and 82, large against the estimates themselves, so read them as small and uncertain rather than precise.
Detached houses make up 8,316 of the 9,078, the remainder being 164 attached, 68 in two-unit buildings, 139 each in buildings of five to nine and of ten to nineteen, and 185 in buildings of fifty or more (B25024). Owners occupy 8,094 of the occupied units and tenants 654 (B25003).
Concentration like that makes the original construction the known quantity, and seventy years makes replacement universal rather than notable. So the documentary trail matters more than the shell: what has been swapped out, on whose watch, and whether the work that enlarged a house was permitted and signed off. A dormer or a rear addition that never closed out its permit is a title-stage problem, not a walkthrough one.
Water has its own district
Retail supply comes from the Plainview Water District, identifier NY2902845 on the state's Nassau contact list, with 34,000 recorded as population served and an office at 10 Manetto Hill Road, Plainview, NY 11803 (public drinking water contacts). The list prints identifiers, populations served and contact addresses and no service boundary at all, so a district office carrying a Plainview address establishes nothing about which system supplies a particular house. One recent water bill from the seller settles that in a single document, and it is worth asking for early rather than at the closing table.
Sewered, on a document with no date
Where the county names a sewer authority for this community, the name it gives is the Nassau County Department of Public Works (sewer authorities by community). No collection-district footnote is attached, and the 34 names the document groups under no public sewer do not include this one.
Two caveats belong with that. Nothing on the document dates it, and it is served with neither a last-modified header nor an entity tag, so its vintage is unknown. A listed community is also no guarantee that a given house was connected; a cesspool left in place at the time stays where it is. Run the address through the Land Records Viewer.
Flood, rail and the limits of a community record
At community level the flood record belongs to the town: community 360483, participating, unsanctioned, map date September 11, 2009, and no Community Rating System rating, which means an insurance quote carries no discount for it (New York NFIP community status records). What that record cannot do is describe a lot. Zone X is no all-clear, the 500-year floodplain sitting inside it, and panels are read address by address at FEMA's Map Service Center. Separately, the state's rail dataset lists no Long Island Rail Road station of this name (MTA rail stations).
The disclosure form turns caveats into questions
For a one-to-four-family home, New York obliges the seller to deliver a Property Condition Disclosure Statement, form DOS-1614-f, revision 06/23, before a binding contract of sale is signed, a duty the form backs with "a credit of $500" to the buyer at transfer of title where it is skipped (Department of State). Its twenty-eighth question is the one that closes the gap this page keeps returning to:
What is the type of sewage system? (Check all that apply) public sewer, private sewer, septic, cesspool — if septic or cesspool, age? Date last pumped? Frequency of pumping?
Question 14 does the same for fuel storage tanks, past or present, above or below ground, and whether any has leaked. The state adds that the form "is not a substitute for any inspections or tests."