Skip to content
Skip to content
TopHapOpen in map
Single Family ResidenceResidential
$9,999,999$1,459 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 95How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $11,000,000 on Dec 2, 2014

1817 CALLE ARROYO

DIABLO, CA 94528
6
Beds
7
Baths
6,855 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
1.54 ac
Lot SizeThe size of the land the home sits on, from county records.
1918
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
17
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.
6
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$10M
$10M low$10M high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$11,000,000 · Dec 2, 2014

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$75,741 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$7,024,000 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$1,430,233
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$5,593,767
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$6,800,000

Climate Risk

Overall riskThe average of the five hazard scores below, on a 0 to 100 scale. Higher means greater projected risk over the coming decades.44
35
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
81
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
47
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
46
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
14
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.1 percent flood zone

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
CountyCONTRA COSTA
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.2011
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
CoolingThe type of cooling or air conditioning in the home.Central
FireplaceWhether the home has a fireplace, and what kind.Yes
GarageWhether the property has a garage, and details like whether it is attached to the home.Garage, Attached
PoolWhether the property has a pool, and what kind, such as in-ground.Yes

Transaction History(6)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

E
Green Valley Elementary SchoolA+
Elementary · Grades KG–5 · 0.9 mi
M
Los Cerros Middle SchoolA+
Middle · Grades 6–8 · 1.1 mi
H
Monte Vista High SchoolA+
High · Grades 9–12 · 1.2 mi

District: San Ramon Valley Unified School District

Neighborhood · ZIP 94528These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.71
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.85
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.593

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.96%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.34%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.8.0%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.2%
PopulationHow many people live in this area.1,042
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.1,912 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$230,686
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$330,622
Average tempThe average temperature here across a full year.59°F
Annual precipHow much rain and melted snow falls here in a typical year.20 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.78%

Owner Tools

Do you own this home?
Claim this home

Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

1817 Calle Arroyo measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Among the most valuable homes in Diablo 94528
  • Among the highest price per square foot in Contra Costa County
  • Among the largest homes in Contra Costa County
  • Has a bigger lot than 98% of homes in Contra Costa County
  • Among the oldest homes in Contra Costa County

What homes are worth in Diablo 94528

Each bar is how many homes fall in that price range. The marker is this home.

This home
$1.5M$7.8M

This home is worth more than almost all homes in Diablo 94528.

How it measures up in Diablo 94528

The dot is this home. The mark in the middle is the typical home in Diablo 94528.

Estimated value$9,999,999
CheaperTypical $3,137,338Pricier

Pricier than almost all homes nearby

Price per ft²$1459
CheaperTypical $856Pricier

Pricier than almost all homes nearby

Living area6,855 ft²
SmallerTypical 4,004 ft²Bigger

Bigger than 93% of homes nearby

Lot size1.54 ac
SmallerTypical 0.74 acBigger

Bigger than 88% of homes nearby

Year built1918
OlderTypical 1975Newer

Newer than 6% of homes nearby

How 1817 Calle Arroyo ranks against every home in each area.
MeasureThis homeDiablo 94528Contra Costa County
Estimated valuepricier than$9,999,999almost all homesalmost all homes
Price per ft²pricier than$1459almost all homesalmost all homes
Living areabigger than6,855 ft²93% of homesalmost all homes
Lot sizebigger than1.54 ac88% of homes98% of homes
Year builtnewer than19186% of homesalmost no homes

About 1817 Calle Arroyo

How much is 1817 Calle Arroyo, Diablo, CA worth?

The TopHap Estimate for 1817 Calle Arroyo, Diablo, CA is $9,999,999 as of Sep 24, 2026. The likely range is $9,999,999 to $9,999,999. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 1817 Calle Arroyo, Diablo, CA last sell?

1817 Calle Arroyo, Diablo, CA last sold on Dec 2, 2014 for $11,000,000, according to the county's recorded deed. TopHap holds 4 recorded sales for this parcel.

How big is 1817 Calle Arroyo, Diablo, CA?

1817 Calle Arroyo, Diablo, CA has 6 bedrooms, 7 bathrooms and 6,855 square feet of living space.

When was 1817 Calle Arroyo, Diablo, CA built?

1817 Calle Arroyo, Diablo, CA was built in 1918, making it 108 years old. The building has 2 stories.

What schools serve 1817 Calle Arroyo, Diablo, CA?

1817 Calle Arroyo, Diablo, CA is assigned to Green Valley Elementary School (elementary), rated A+; Los Cerros Middle School (middle), rated A+; Monte Vista High School (high), rated A+. All sit in San Ramon Valley Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 1817 Calle Arroyo, Diablo, CA compare to other homes in Diablo 94528?

Among the 393 homes in Diablo 94528, it is worth more than almost all of them ($9,999,999 against a typical $3,137,338), its price per square foot is higher than almost all of them ($1459 against a typical $856), it is bigger than 93% of them (6,855 ft² against a typical 4,004 ft²), its lot is bigger than 88% of them (1.54 ac against a typical 0.74 ac) and it is newer than 6% of them (1918 against a typical 1975). Measured against all of Contra Costa County, it is worth more than almost all homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 1817 Calle Arroyo, Diablo, CA?

The 2025 property tax bill for 1817 Calle Arroyo, Diablo, CA was $75,741. The county assessed it at $7,024,000.

More homes on Calle Arroyo

Closest homes

More homes in Diablo 94528

Assigned schools

Explore the area

See this home in context

Open 1817 Calle Arroyo on TopHap’s interactive map to compare it against every sale nearby, overlay school zones and flood risk, and run a CMA.

Open in map
A flyover of TopHap's photorealistic 3D map, with recorded sale prices pinned to homes
Search any address, city, zip, or county…3D$1.9M$6.25MOpen in map