Yes, with two things to plan around. Rain is plentiful, about 56 inches a year. The ground is steep, with slopes averaging about 23%. That raises the cost of a driveway, septic, and foundation. NOAA counts three hurricane-strength storms within 50 miles since 1975, so build to the wind code and plan for long outages.
What the land says
Rain
Rain can supply much of a household's water with a large tank. A garden mostly waters itself in normal years.
About 56 inches a year (University of Hawaii Rainfall Atlas)
Wells
Typical well depth. Budget for a mid-range well.
The typical well here is about 250 feet deep; a well typically runs $23,000 to $51,000
Growing season
Long enough for a spring and a fall garden.
About 365 frost-free days, USDA zone 12a; last frost about January 1, first about December 31
Sun
Good sun. Size the array and battery bank for winter.
About 5.4 hours of full sun a day, averaged over the year
Flood
Flood zones run along creeks and rivers here. Look up the parcel on FEMA's flood map.
FEMA maps flood zones within a quarter mile in places
Wildfire
Low wildfire risk.
U.S. Forest Service wildfire hazard map: Very Low to Moderate here
Storms
Expect about two hurricanes within 50 miles over 30 years. Build to the wind code and keep a week of fuel and water.
NOAA: three hurricane-strength storms within 50 miles since 1975; no strong (EF2 or stronger) tornado within 25 miles since 1990
Terrain
Steep in places. Driveways, septic, and foundations cost more.
Slopes average about 23%, about 410 feet above sea level
Soil
Good ground for a standard septic system. The county's soil test decides.
Silty clay loam, well drained (USDA soil survey). A standard system typically runs $5,000 to $10,000
Road
Dirt tracks. Plan to build or maintain your own road.
Nearest road often a dirt track, about 0.7 miles away (OpenStreetMap)
Check a Hawaii parcel, or plan the one you own
Get a free 0-100 off-grid score.
A step-by-step build plan, sizing your solar, water, garden, septic, heat, and buildings.
Is it legal here?
Zoning
Kauai County zones land outside its towns and publishes its zoning map. Our free lookup shows the district for any address.
Building code
Hawaii has a statewide building code, with a residential code based on the 2018 International Residential Code. Each county adopts it with its own changes and enforces it through the county building department, so plan on a county building permit for a house.
Rainwater
Collecting it is allowed.
Composting toilets
Allowed with a permit and an approved unit.
Water rights
A mix of two systems. Ask the state water office before you drill a well or dam a creek.