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Comment by jdeibele | Hacker News Reader

We were going to buy a house overlooking a creek but were told that an offer had just been accepted. A few days later, we got a call that for some strange reason the sale had fallen through. My wife and I started researching and ran across https://floodfactor.com. It said that there was a 97% chance of a foot or more of water in the house in the next 15 years, incurring more than $100,000 of damage.

I wasn't familiar with floodfactor.com but they were linked from realtor.com I'm a little cynical about that - hey, yes, your house flooded but you should have checked that link and it's not your realtor's fault - but it's a sign that their information should be taken seriously.

Now they do wildfire and "heat" risks as well as flooding. They might introduce something like water supply risk and other things.

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Being in a flood plain is a mandatory disclosure and requires additional flood insurance. So they probably realized it when they went to get homeowners insurance and it was much more expensive than they thought it would be.

On the flip side, the person that we bought our house from had the map showing the flood plains as part of the overview of the house and that the house that was outside of the flood plain. She was adamant about it because the house is up on a slight hill, so both neighbors are in the flood plain and had to fight insurance before that the house was not actually in the flood plain.

Flood plain disclosures are computed looking back 30 years, which is no longer a good predictor of the risk over the next 30 years.

So, it's good to check the climate change maps as well as any mandatory disclosures.

Yeah, floodfactor is a great tool.

In a similar vein, check out geological surveys for karsts and sinkholes if you live in an area where bedrock is comprised of soluble rocks (which is much of populated earth). I know this seems outrageous, but increased rainfall doesn't just flood creeks and rivers, it can overload sewage systems. And if an overloaded sewage system means water has to find it's own way.

This doesn't just effect your house. Think about the impact of a road to your house sinks. IME, these can take months to get fixed.

One of the clearest memories I have of my high school education was when my high school Earth Science teacher shared his process on evaluating the surrounding geology of a property before purchasing his home. Home ownership seems like an increasingly distant goal but I look forward to putting that lesson into practice one day.

Rest in peace Mr. F.

Just tried it....I'm not very convinced in it's modeling.

I live near the top of a large, steeply sloped hill and water does not flow past/towards the house. It claims there is a 97% chance of a foot or more of water reaching my house in the next 30 years. It at least doesn't claim there would be damages, but there's really no way for what it claims to actually occur.

The FEMA maps also have reliability problems but I'm not sure this is more reliable.

No idea if relevant, but a friend of mine lives on the side of a steep hill and... got flooded recently.

They had heavy sudden rainfall, exceeding the capacity of drainage pipes. He just got superficial damage, his next door neighbour had 1ft of water everywhere on ground floor. No basement at least.

I'm not sure I'd believe those numbers. Our house is borderline uninsurable due to wildfire risk, and they give it a 2/10 risk for wildfires.

This project from propublica is also good, but similarly underestimates wildfire risk in our area:

https://projects.propublica.org/climate-migration/

Wouldn't insurance companies have an incentive to overestimate risk though? Not saying you should ignore the danger... just, not sure the two assessments should be expected to line up.

Thanks for sharing. This is interesting and useful. Online real estate companies are very lazy and bad when it comes to adding additional useful info. Once they got a monopoly position and access to MLS in every state (not easy feat, impossible to do today as a founder without serious cash) they just started resting on their laurels.

Not only do I care about these kinds of risks, I also care about neighborhood quality and architectural design. None of this is measured let alone searched for. Walk score is a start but again same problem as Risk Factor.

Properties in a flood plain have a mandatory disclosure and require special, expensive insurance.

This likely came up after the offer was accepted.

When the realtor called to say that the previous offer had fallen through and wanted us to buy, he said a couple of times that the owner didn't have to have flood insurance.

We hadn't said anything about flood insurance. So it seemed like either the disclosure scared the other buyer or they found riskfactor.com or something like that.

Beautiful house, beautiful view. Also a quarter mile below a earthen dam 250 feet high and a few feet above a creek that was raging in 1996, several years before this house was built.

You only need to have flood insurance if you have a mortgage. Our home is in a floodplain, but the prior owner was the first owner, and build the home himself. When we bought the home, we had to petition FEMA to remove the home from the flood plain.

This is great. We’re looking at a few areas for a potential vacation home and trying to estimate future climate risk is something we’d like to attempt to account for.

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