Flood Resilient Landscaping

Landscaping can help reduce your flood risk by redirecting, absorbing, and storing stormwater. A well-designed landscape can act like a natural sponge and filter rain and snowmelt that would otherwise run off hard surfaces and pool around buildings. It can also help slow and absorb coastal flooding.

Landscaping cannot redirect floodwaters in a manner that impacts neighboring properties or protected wetland resource areas. View the Boston Conservation Commission’s guide to locate wetland resource areas. Landscaping that could impact protected areas requires review and permitting. Before taking any action, please contact the Boston Conservation Commission at cc@boston.gov to learn about what additional permitting steps you may need to complete. 

Consult with licensed and qualified professionals and get at least three quotes to compare prices. All information, including installation details, cost estimates, and useful life expectations, is provided for informational purposes only and may vary based on property conditions, labor rates, materials, and other factors. For additional guidance, visit the Office of Green Infrastructure’s Planning and Design Resources.

Regrade Your Property

Regrade and adjust the soil on your property to prevent pooling near your foundation. Slope the land away from your home or business at least 6 inches over 10 feet to draw water away from your foundation and into a drainage area like a rain garden or swale. You can also adjust the soil to improve water absorption and plant growth. Water runs quickly through sandy soils, while clay soils retain moisture. Too much of either can contribute to flooding. Loam soil, which has a mixture of sand, silt, and clay, provides the best conditions to reduce flood risk and promote plant growth.

Installation: Typically takes 1-5 days, depending on the size of the property. Minor regrading does not require a permit, provided it does not adversely affect adjacent properties by redirecting water. A permit from Inspectional Services is needed for larger construction projects, retaining walls, significant excavation, and changes to drainage patterns.

Cost: A 1,000 sq. ft. area generally costs $1,000–$3,000

Useful life: 15-20 years. The soil may settle in the first 1-2 years and may require minor adjustments.

Build a Rain Garden

Build a rain garden to absorb rainwater. Rain gardens are shallow, planted basins designed to collect rainwater runoff from hard surfaces like roofs, driveways, sidewalks, or streets. The collected water soaks into the ground or is absorbed by plants that help filter pollutants.

Installation: Rain gardens should be 6-12 inches lower than the ground around them and located at least 10 feet from your foundation and septic system. Use a soil mix of 50-60% sand, 20-30% topsoil, and 20-30% compost to ensure proper drainage. Select perennial, native plants that can tolerate wet soil and occasional drought. Deep-rooted grasses and shrubs provide structure. Place one plant per square foot, with the most moisture-loving plants in the center and more drought-tolerant plants on the edges. Use a wildflower seed mix instead of mulch, which contains phosphorus, a pollutant. For additional guidance, view the Boston Water and Sewer Commission’s Rain Gardens guide.

Cost: $100 - $3,000 depending on size and complexity.

Useful life: 15-25 years with regular maintenance. Remove sediment when it exceeds one inch to prevent clogging.

Install a vegetated swale

A vegetated swale, or bioswale, is a shallow, gently sloped channel densely planted with grasses, shrubs, or other vegetation that’s designed to carry, slow, and absorb stormwater runoff. 

Installation: Takes 1-3 days. A swale is best placed downhill from roofs, driveways, or parking areas and should be at least 10 feet from your foundation. Avoid making the channel too steep or deep. A shallow, wide swale is more effective than a deep, narrow trench. Loosen the existing soil and adjust it to have a mix of sand, silt, and clay. Stabilize the edges of the swale with stone or turf and densely cover the channel with plants that can tolerate wet and dry cycles. 

Cost: $5-$20 per linear square foot

Useful life: 20-25 years with regular maintenance. Remove sediment when it exceeds one inch to prevent clogging.

Replace asphalt with porous pavers

Hard surfaces like traditional, asphalt driveways contribute to stormwater runoff. Replacing these surfaces with porous materials such as permeable interlocking concrete pavers or plastic grid pavers filled with gravel or grass allows water to soak into the ground, which reduces flood risk. 

Installation: Professional installation is recommended, and regular maintenance is required to remove debris from the porous material. Remove existing asphalt and dig down 12–14 inches for a stone reservoir. Lay a filter fabric to prevent soil mixing, followed by several inches of 3/4" crushed stone for water storage. Add a thinner layer of 1/4" stone, install the pavers in a pattern, and secure with edge restraints. Fill the gaps between pavers with fine joint stone to allow water to flow through. 

Cost: Permeable Interlocking Pavers are $18–$35 per square foot. Plastic Grid Pavers cost $10-$20 per square foot, including gravel for the base and either smaller stone gravel or soil and grass for the fill.

Useful life: 25-60 years with regular maintenance. Avoid applying sand in the winter months to prevent blocking the spaces between the fine gravel; salt application is preferred. Vacuum sweeping is required at least twice per year to remove dirt and debris from the pores. Replenish joint stone after vacuum sweeping.

Install a French drain

Install a French drain, an underground pipe that collects water from above and below the surface and redirects it away from your foundation. Interior drains in a basement typically discharge into a sump pump pit. Exterior drains, along a driveway or in an area that typically floods, need a low-lying area away from your foundation to outlet water and cannot impact neighboring properties. 

Installation: Typically 2-7 days and requires a licensed professional. Drain installation must adhere to zoning restrictions and requires a plumbing permit through Boston Inspectional Services. If the drain discharges into the city’s stormwater system, a drainage discharge permit is needed from the Boston Water and Sewer Commission.  

Cost: Based on linear square footage. Interior drains range between $4,000 and $15,000. Exterior drains range between $2,800 and $6,500.

Useful life: 20-30 years with proper sloping, durable PVC pipes, and regular cleaning.