The short answer
Published local data puts most basement waterproofing projects in the region at roughly $2,500 to $8,200, with averages between about $4,800 and $5,800:
| Item | Typical range | Source |
|---|---|---|
| Washington, DC | $3,494–$8,219 (average $5,771) | Angi |
| Arlington, VA | $3,875–$8,013 typical (average $5,497) | HomeAdvisor |
| Silver Spring, MD | $3,498–$7,853 typical (average $5,497) | HomeAdvisor |
| Baltimore, MD | $2,486–$6,756 typical (average $4,789) | HomeAdvisor |
| National, for comparison | $3,000–$10,000 (about $5,000); Angi $2,300–$7,575 (average $4,920) | Fixr; Angi |
| Sump pump installation | $500–$4,000, about $1,400 on average | This Old House, 2026 |
Published figures for orientation (checked October 2026), not quotes.
What drives the price in this region
- Rowhomes and English basements (DC, Baltimore): narrow basements mean less wall to drain, but tight access, hand-carried debris and finished living space push labor up. Exterior stairwells and areaways often need their own drains.
- Finished suburban basements (Montgomery, Fairfax, Arlington): many 1950s–1980s homes have finished lower levels, so walls and flooring have to come off along the drain line.
- Clay soils: Fairfax County publishes a homeowner’s guide to marine clay, which swells and shrinks and drains poorly; foundations on these soils are more likely to need crack repair or wall stabilization along with drainage.
- Sewer backups: in older DC neighborhoods with combined sewers, a backwater valve may be the real fix rather than wall drainage.
- Licensing and permits: Maryland requires an MHIC license, Virginia a Board for Contractors license for jobs of $1,000 or more, and DC licenses home improvement contractors; permits add cost and time.
Rebates and programs
DC Water’s Backwater Valve Rebate Program reimburses eligible property owners with documented sewer backups up to $6,000 for buying and installing a backwater valve. Check eligibility before the work. See backwater valves.
How to keep the cost down
- Identify the source first – floor drain (sewer), one spot (surface water) or along the walls (groundwater).
- Fix gutters, downspouts, stairwell drains and grading before buying a system.
- Compare at least two written quotes with the same scope: walls, feet of drain, pump and backup, warranty, permits.
- Verify the license: MHIC number in Maryland, DPOR license in Virginia.
Local pages
Washington, DC · Maryland · Northern Virginia
Sources
- Angi: Basement waterproofing cost in Washington, DC
- HomeAdvisor: Foundation or basement waterproofing costs in Arlington, VA
- HomeAdvisor: Foundation or basement waterproofing costs in Silver Spring, MD
- HomeAdvisor: Foundation or basement waterproofing costs in Baltimore, MD
- Fixr: How much does it cost to waterproof a basement? (2026 data)
- Angi / HomeAdvisor national figures, as quoted by Bob Vila: Basement waterproofing cost
- This Old House: Sump pump cost
- Fairfax County: Homeowner’s guide to marine clay
- DC Water: Backwater valve rebate program
- Maryland Department of Labor: Maryland Home Improvement Commission, check a contractor
- Virginia DPOR: Board for Contractors (license lookup)