REOS Software › Site analysis
Site analysis
Find out what's buildable before you commit
REOS puts flood zones, wetlands, slope, soils, roads, zoning and utilities on one map, then works out how much of the site you can build on and how many lots the zoning allows.
Figures as of October 5, 2026.
The layers
Flood zones come from FEMA's National Flood Hazard Layer, including floodways, and wetlands from the National Wetlands Inventory. Elevation is from USGS, with 2-foot contours wherever the county publishes them, and soils are from USDA soil surveys. You also get the road network and each parcel's frontage, zoning districts with their lot size and width rules, the county or city future land use plan, electric transmission lines and gas pipelines with their easements, and published water and sewer mains, pump stations and service areas.
From the map to a lot count
REOS starts with the gross acreage and takes out flood zones, wetlands, stream buffers, utility easements and steep slopes to get net buildable acres. Then it applies the zoning district's minimum lot size and width to estimate how many lots fit. That's the number to hold up against the listing.
To try the math on your own numbers first, use the free subdivision lot yield calculator, or read how many lots per acre a site really holds, with a table by lot size.
Sewer
Sewer is where a lot of deals fall apart, so REOS goes further on it. Where the mains are published, it finds the nearest one, routes a line to it and checks the elevations along the way. That tells you whether the site can drain by gravity or will need a pump station, and gives you a rough cost range. If a county doesn't publish a sewer map, REOS marks sewer as unavailable. That only means there's no public data to check. The service may well be there.
Site analysis in REOS is a screening tool built on public data. It doesn't replace a survey or an engineering study, so have both done before you close.
The same analysis feeds the deal underwrite, so the lot count and sewer cost carry straight into the numbers.
Questions
Where does the flood and wetland data come from?
Flood zones are from FEMA's National Flood Hazard Layer and wetlands from the National Wetlands Inventory.
Does REOS show whether sewer is available?
Where the county or utility publishes its water and sewer mains, yes, along with the distance and whether the site drains by gravity. Where nothing is published, REOS tells you that.
Is this an engineering study?
No. It's a fast screen built on public data. Have a surveyor or engineer confirm it before you commit to a site.
How is the lot count worked out?
From the net buildable acres, after flood zones, wetlands, buffers, easements and steep slopes are taken out, and the zoning district's minimum lot size and width.
See it on a site you're looking at
Bring a listing or a parcel you're working on, and we'll run it on the call.