Inside a fifteen-minute summer storm
- Minute 0
- Heavy rain and often hail begin, sometimes after a hot, dry afternoon.
- Minutes 2 to 5
- Gutters overflow, hail and leaves block downspout openings and alley inlets.
- Minutes 5 to 10
- Alleys and street gutters run like shallow streams. Water ponds in low spots near garage aprons and back gates.
- Minutes 10 to 15
- Water finds a path into exterior basement stairwells, under garage doors and against foundations.
- After it stops
- Standing water usually drains off fairly soon, but basements on low sides of the block may already be wet.
Why the back of the lot is often the weak side
Many Wash Park blocks have alleys running behind the houses, with detached garages along them. Alleys were built to move vehicles and trash trucks, not to manage stormwater, and over time their surfaces settle, get repaved at different heights, and develop low spots. During a downpour, the alley carries runoff from roofs, garages and pavement toward the nearest inlet.
When water in the alley is higher than a yard or a garage floor, it flows in. From there it can cross a yard toward the house, collect in an exterior stairwell leading to the basement door, or drain into a window well at the back. Older houses with an outside basement entrance are especially exposed, because that stairwell is a deep, open pit with a single small drain at the bottom, often clogged with leaves.
Hail makes everything worse. Pea-sized hail washes into gutters, downspouts and drains and packs into slush that blocks them while the rain is still falling.
What to look at after the storm
- IfWater came in through a basement door at the bottom of exterior stairsClear and test the stairwell drain, and consider a raised threshold or a cover over the stairwell.
- IfThe garage floor flooded from the alleyRaise anything stored on the floor and ask about a trench drain or regrading at the garage apron.
- IfWater crossed the yard toward the houseLook at yard grade and whether a swale could redirect flow toward the alley or street.
- IfAn alley inlet seems undersized or always blockedReport it to the City and County of Denver through its 311 service so the right department can look at it.
- IfWater reached finished basement roomsExtract and dry promptly; storm runoff picks up debris and contaminants, so treat it with care.
Getting ready for storm season
- Clean gutters and downspout openings in late spring, before thunderstorm season.
- Clear leaves and grit from the exterior stairwell drain and test it with a hose.
- Keep the alley side of the garage free of items that wash into the inlet.
- Store garage items on shelves rather than the floor.
- Know where your main shutoff and breaker panel are in case water reaches the basement.
Common questions
Does homeowners insurance cover water that flowed in from outside?
Surface water entering from outside is often treated as flood and excluded from standard homeowners policies, while hail damage to the roof that lets rain in is often covered. Read your policy or ask your agent about flood coverage and how each type of water is handled.
General information for Washington Park, not a quote or professional advice. In an emergency, call 911.