Your dry well needs enough storage for the runoff entering it and soil that absorbs that water between storms. The right size depends on the roof sections, driveway, patio, and other areas connected to the system—not simply the size of your property.
Start with those measurements before choosing a tank or deciding how much excavation the project needs.
How Much Water Does My Dry Well Need to Hold?
For perspective, one inch of rain falling over 1,000 square feet equals about 623 gallons of water before losses. That’s a rainfall-volume example, not an automatic recommendation for a 623-gallon dry well.
The actual storage requirement also depends on the storm the system is designed to handle and how much water infiltrates during that storm. Ask your drainage contractor what calculations support the proposed size.
Does Slow-Draining Soil Mean I Need a Bigger Dry Well?
Not automatically. Extra storage holds more water, but it doesn’t fix ground that won’t absorb it.
Testing at the proposed installation depth establishes how quickly water enters the soil. Seasonal groundwater and bedrock also affect whether the location is suitable. If those conditions rule out infiltration, the property needs a different drainage approach—not just a bigger hole.
Can My Roof and Driveway Share One Dry Well?
Yes, provided the design accounts for their combined runoff and the different debris each source carries. Driveway runoff needs appropriate pretreatment to keep sediment and pollutants out of the infiltration system.
Include every connected downspout and paved area in the calculations. Adding another collection point later changes the amount of water the system receives, so that addition needs a capacity check first.
Is One Large Dry Well Better Than Several Smaller Ones?
Neither layout wins automatically. Multiple connected structures provide additional storage, while their placement depends on available space, soil conditions, and the areas being drained.
Ask the contractor to explain why the proposed arrangement fits your property. Compare usable water-storage capacity, not just tank dimensions: stone-filled sections hold water in the spaces between the stones, not throughout the entire excavation.
Will a Properly Sized Dry Well Prevent Every Overflow?
No drainage system has unlimited capacity. A dry well needs an overflow route for storms that exceed its design capacity, even when the storage and soil conditions are suitable.
Before approving the project, ask where excess water will go.
Who Should I Call for Dry Well Sizing in White Plains?
F. La Rocca & Sons installs dry wells in White Plains and throughout Westchester County. Call 914-632-4819 to discuss the areas you need to drain and the installation options for your property.
Have approximate roof or paved-area measurements ready, along with photos of the collection points. Mention any planned driveway expansion or new patio so the conversation includes those future drainage needs.
