Most buyers are not picking between a dangerous lot and a safe one. They are picking between two that both looked fine on a sunny Saturday. A field-by-field method for letting hazard data break the tie, plus a tie-break checklist.
Most buyers are not choosing between a dangerous lot and a safe one. They are choosing between two lots that both looked fine on a sunny Saturday afternoon, both inside the budget, both close enough to work. This post is a method for putting two addresses next to each other and letting the data break the tie.
Do not read report A from top to bottom and then start report B. By the time you finish the second one you will have forgotten half of the first, and you will end up comparing feelings instead of numbers. Go field by field instead. Open both reports, and write the two values next to each other on one sheet of paper:
Nine lines. It takes ten minutes, and it is the only reliable way to see which differences are real and which are just two documents that read differently.
Two lots can both say "Level 3" for flood and still be very different places to live. What matters is the scenario that level appears in. A lot that reaches Level 3 in the 5-year scenario is describing something the model expects to happen often. A lot that only reaches Level 3 in the 100-year scenario is describing a rarer, bigger event. Same label on the page, different decade of your life.
If you remember one thing from this post, remember to read the return period next to the level, never the level on its own. We explained that idea at length in flood return periods explained, and it is the single most misread number on any flood map.
The same care runs the other way. A lot marked Level 1 that sits noticeably lower than its neighbours, on a street with no working drainage, can still take water the map never promised. Hazard mapping is a screening tool. It is not a forecast for your specific gate on a specific night.
Some fields describe things you can design around. Others describe things that come with the land forever. Sort your circled differences into those two piles before you decide.
Hard to change:
Easier to change, at a cost:
A lot that loses on flood level but wins on fault distance may still be the better buy, because one of those two problems has a builder and a budget attached to it and the other does not.
A missing value is information too. Our data comes from national Philippine sources, and coverage is not perfectly even. If both reports show no nearest waterway, that may mean there genuinely is no mapped creek nearby, or it may mean the waterway data does not cover that tile well. Same for a flood layer that returns nothing in a remote municipality.
When a field is blank, treat it as unanswered rather than as good news. That is the moment to go look with your own eyes: walk the property line, follow where the water would go downhill, and ask the neighbours who have lived there ten years.
A CheckHazard report screens an address against national hazard datasets. It reads the layers at a point, it tells you which mapped zones that point falls in, and it puts distances on the nearest fault and waterway. It does not know the fill history of the lot, the quality of the drainage the developer installed, whether the neighbour raised their lot and pushed water onto yours, or what the soil is doing three meters down. Two lots can score identically and still behave differently in a storm for reasons no national map captures.
Use the comparison to narrow the field and to know what to ask. Then spend the money on a soil test and a site visit for the one you are serious about.
CheckHazard does not replace a professional geotechnical or engineering survey.