Flood is excluded from every homeowners policy in the country

The mapped flood zone decides one thing reliably: whether a lender requires coverage. It is a much weaker guide to whether you need it. FEMA has long reported that more than 20 per cent of flood claims come from properties outside high-risk flood areas — which is precisely where owners are least likely to carry a policy, because no lender ever asked.

The practical read is the opposite of the intuitive one: being outside a high-risk zone is a reason to price flood coverage rather than to skip it, because that is exactly where the premium is lowest. Recent Southeast history — Harvey's flooding across the Houston metro, creek flooding through Middle Tennessee — ran heavily through neighbourhoods the maps called low-risk.

The National Flood Insurance Program is the default: federally backed, sold through ordinary agents, with limits of $250,000 on the building and $100,000 on contents for a home. Private flood insurers now compete alongside it, often with higher available limits, shorter waiting periods, and coverage the NFIP does not offer, such as living expenses while the home is uninhabitable. For a home whose rebuild cost exceeds the NFIP cap, the private market is where adequate limits live.

One timing rule matters more than everything else: NFIP policies generally carry a 30-day waiting period before coverage takes effect. The main exception is a purchase — a policy bought in connection with a loan closing starts with the loan. What the waiting period rules out entirely is buying cover with a storm on the forecast map.

Between covered pipe bursts and excluded floods sits a third category: water backing up through sewers, drains, or a failed sump pump. Standard policies exclude it, flood policies do not cover it either — it is its own endorsement, usually modest in cost, added to the homeowners policy. In practice it is one of the most frequently used water coverages a homeowner can carry, and one of the most frequently missing.