Start with gutters, downspouts and surface water. If water persists, compare drainage approaches and prepare useful questions for a qualified local contractor.
Hydrostatic pressure, sump redundancy, and backwater defense
Stop surface runoff, groundwater uplift, and sewer surcharges before water enters
Even a single inch of interior floodwater causes tens of thousands of dollars in structural, electrical, and mold damage. Defending a home against severe rainstorms requires matching pump discharge capacity at actual total dynamic head, isolating municipal sewer backflow, and maintaining code-compliant window well egress.
Is this the right starting point for you?
- Who this is for
- Homeowners with basements, crawlspaces, below-grade egress windows, or low-elevation sanitary sewer laterals exposed to heavy storm runoff.
- First decision
- Is your primary water-intrusion pathway surface grading and window wells, subsurface hydrostatic groundwater overwhelming the sump pit, or municipal sanitary/storm sewer backup?
- Surface grading and downspout extensions before mechanical pumping
- Total Dynamic Head (TDH) flow curves over zero-head pump marketing claims
- Independent DC battery backup and check-valve isolation for grid blackouts
Choose what applies
If the broad starting guide is more than you need, choose the question that fits your next decision.
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If a grid outage during heavy rain would stop your primary basement sump pump.
Battery Backup Sump Pump Sizing: Pump Curves, Battery Capacity & Site Conditions -
If municipal storm or sanitary main surcharging risks basement drain backup.
Sewer Backwater Valve vs. Overhead Sewer: Comparing Backup-Risk Options -
If below-grade window wells collect surface runoff without compromising emergency egress.
Window Well Drainage and Egress Covers: What to Check Before Storms
3 additional planning guides
More Storm & water defense guides
Check the updated date, sources, assumptions, and safety limits inside each guide before acting.
A doorway barrier is one part of a site-specific flood plan. Use this worksheet to compare exact product documentation and know when to leave the area.
Cold weather can block a sump discharge line. Check the visible outlet, understand one type of relief fitting, and leave plumbing changes to qualified help.
Before you begin
Why does a sump pump fail during a major storm even when the pump motor works?
The most common storm failures are grid power loss, primary float-switch mechanical jamming in a narrow basin, frozen or obstructed exterior discharge lines, or an undersized pump selected by 0-foot lift ratings rather than actual 10-to-15-foot Total Dynamic Head (TDH). Read battery backup sump pump sizing guide.
Does a sump pump stop municipal sewer backups?
No. A groundwater sump pump only evacuates the perimeter foundation drain tile. Municipal sanitary or combined sewer backups enter through basement floor drains and low plumbing fixtures, requiring an IPC-compliant backwater valve or overhead sewer conversion. Read sewer backwater valve vs overhead sewer guide.
Can I bolt a basement window well cover shut to keep floodwater out?
Never permanently bolt or padlock an emergency escape and rescue window well cover. IRC Section R310 requires egress window well covers to be openable from the inside without keys, tools, or special knowledge and with no more than 15–20 pounds of force. Read window well drains and egress flood covers.
Keep your plan current
Small updates. A more prepared home.
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