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Stormwater Management

Rain Barrels


Stormwater Management Resources

The EnviroHouse provides examples, resources and techniques to manage stormwater on your property. Effective stormwater management can help reduce pooling or flooding, protect foundations, and replenish groundwater supplies. At the EnviroHouse,  you can explore options like permeable pavers, rain barrels, rain gardens, green roofs, tree planting, suitable irrigation, and ideas for replacing hard surfaces.



Why does stormwater management matter?

Rainwater falling on hard surfaces such as roads, sidewalks and roofs creates stormwater runoff that can carry oils, heavy metals, fertilizers and pesticides that pollute groundwater supplies and threaten aquatic habitat.  Choose landscaping features that can reuse and absorb the rainwater falling on your yard to help reduce sources of polluted runoff and recharge groundwater. 


Did You Know? Stormwater flows untreated into all of our waterways.  If It Hits the Ground, It Hits the Sound!

Discover stormwater management options in the sections below and explore examples of each at the EnviroHouse. Exterior displays and signage are accessible for visitors when the Tacoma Recovery and Transfer Center is open.

Permeable Pavers


Permeable surfaces allow rainwater to drain through and soak into the ground naturally. Rainwater falling on impermeable hard surfaces such as roads, sidewalks and roofs creates stormwater runoff that pollutes groundwater supplies and flows, untreated, directly into waterways flowing into the Puget Sound.
Installing permeable pavers can filter and help decrease the amount of toxic material such as fertilizer, pesticides, oils, and chemicals that pollute stormwater runoff and harm our environment and aquatic habitat.


Permeable Pavers

1. Permeable Pavers allow rainwater to soak through


2. Crushed gravel base provides storage for rainwater, allowing it to gradually soak into the soil


3. Soil base needs to absorb and infiltrate rainwater. Do a soil test to make sure.


 Pavers 1  Pavers 2  Pavers 3  The EnviroHouse features examples of the following materials and products:
  • Interlocking concrete pavers with gaps for gravel to let water drain through
  • Recycled plastic interlocking grid systems to hold gravel in place
  • Pervious concrete and asphalt products
  • Broken concrete, salvaged clay bricks, crushed quarry rock, and woodchips
 Interlocking permeable concrete pavers made to look like brick or stone. Permeable pavers made from decorative gravel. Plastic grid systems for heavy traffic areas on grass and gravel surfaces.


Current information for Tacoma residents on stormwater, flooding, paving surfaces, municipal codes, requirements, and permits is available at the City of Tacoma Stormwater website.


Rain Barrels


Rain BarrelHarvest the Rain with Rain Barrels 

A rain barrel is a container used to catch rainwater flowing from a roof downspout. Rain barrels store rainwater for watering plants, cleaning tools, car washing or other outdoor uses. CAUTION: Do not drink water collected in rain barrels; it is not clean enough for humans or pets. 

Environmental Benefits of Rain Barrels 

Capturing rainwater runoff from roof surfaces can reduce excess water on your property, redirect the flow away from building foundations, replenish the water table and decrease the amount of storm water runoff from hard surfaces into the street storm drainage system. 

Is it Legal to Harvest Rainwater?

Yes! In October 2009, Washington State ruled (DOE POL 1017) “that a water right is not required for on-site storage and use of rooftop or guzzler collected rainwater…” unless the impact negatively affects “instream values or existing water rights.”  

What is a Catchment System? 

Rainwater catchment systems are containers used to hold the captured rainwater. They can be a variety of sizes, shapes, materials, and designs depending on how elaborate the system becomes. The roof catchment area is equal to the total square feet of your house plus the extension of your eaves. 

Buy Ready Made  

Rain barrels may be available from local craftsmen who typically make them with 50-70 gal. repurposed food grade barrels. Manufactured barrels are often available at local hardware stores and online sources.  

Make Your Own Rain Barrel

You need a few basic tools, a solid, opaque barrel with a screw on lid, and various parts: PVC elbows, overflow valves, hoses, fittings, spigots, window screening and cinder blocks to elevate the barrel for gravity flow.   

NOTE: A full 60-gallon rain barrel weighs about 500 pounds! Be sure it’s level and secured when installed. An earthquake strap to secure the barrel to the house is a must in the Tacoma area.


Maintain Your Rain Barrel 

  • Keep gutters clear to ensure water flows to downspouts; clean every year or so, especially if there are nearby trees dropping leaves. 
  • Make sure the rain barrel and all of its parts are securely fastened. 
  • Check for damage or blockage periodically; repair leaks and replace any damaged parts. 

Learn More

Visit the EnviroHouse to examine the interconnected rain barrels onsite and see how the system works. Parts and equipment lists may be available.

View EnviroHouse Webinar and How-To Videos: 
How to Make, Maintain, and Install Rain Barrels

Helpful Tip: If you DIY and don’t have tools, check out the Tacoma Tool Library online to borrow what you need!


Rain Gardens


What is a Rain Garden?   

Rain gardens are shallow depressions designed to catch rainwater from surrounding hard surfaces such as roofs, walkways and driveways, allowing it to soak into the earth. Water from downspouts and overflow from other catchment systems such as rain barrels, dry stream beds and rain splash boxes can be directed to a rain garden to capture and hold water to soak in rather than create runoff. 


Rain Gardens



Did you know? The Tacoma-Pierce County area receives 40-50 inches of rain per year. This creates runoff that could be directed to a rain garden to replenish ground water and reduce pollution and flooding.


Why Create a Rain Garden  

As the Puget Sound region has grown over the years, native forests, farms and soils that absorbed rainwater have been replaced with more roads, parking lots, rooftops and other hard surfaces. When runoff accumulates from hard surfaces, it gathers pollutants as it flows untreated through storm drain systems (storm drain pipes, roadside ditches, detention ponds) and enters local waterways, frequently ending up in the Puget Sound. 

What are the benefits? 

Implementing Low Impact Development (LID) systems such as a well-designed rain garden can ease the impacts on local storm drain systems, reduce stormwater runoff and flooding, minimize pollutants reaching our waterways, replenish ground water and help protect your home’s foundation. Landscaped with native and low-maintenance plants, rain gardens provide native habitat for beneficial birds, butterflies, and bees.  

How do I know it will work? 

Creating a rain garden is a labor of love and is often no small expense. Check the resources below for guidelines on how to do a soil test, check on legal requirements and setbacks, and get technical advice. 

  • Soils must be loose enough to allow water to infiltrate. Do a soil test; dig a test hole to see how fast water is absorbed into the ground (best done in the wet season). 
  • A thick layer of rain garden soil stores water and nutrients for plants and helps absorb pollutants. Amended soil depth should be at least 24 inches. 
  • The rain garden needs an inflow channel and an emergency overflow that sends excess water to the stormwater system. 


Call 811CALL BEFORE YOU DIG: Call 811 a few business days before you begin any digging, including common projects like planting trees and shrubs or installing fences and mailboxes to have underground utilities marked.  Call 811 or 1-800-424-5555 or visit washington811.com    


DIY or professional installation?  
Creating a rain garden is best accomplished as a team effort or with the help of a professional. Either way, you will need to make certain decisions related to planning, design, legal matters such as setbacks and possible permits, managing surface water runoff, design, product materials, installation process, tools and equipment or hiring contractors if desired. 


Additional Resources:


Green Roofs


Green RoofAdd beauty and functionality with a green roof on an accessary space such as a garage, shed or chicken coop. Install over a structurally reinforced, waterproofed roof surface using a lightweight amended soil mix and drought-tolerant, low maintenance native plants. 


Did you know? According to the Environmental Protection Agency (EPA), the surface of a green roof on a hot summer day can be as much as 90° F cooler than the surface of a traditional rooftop.


A green roof can:  

  • Double a roof’s lifespan when installed correctly 
  • Provide natural insulation and temperature regulation inside a building, reducing heating and cooling costs by 20-30% 
  • Absorb CO2, filter air and remove heavy metals and pollutants 
  • Collect rainwater and reduce storm water runoff 
  • Create habitat for pollinators and local wildlife

Structural Note: A green roof with 3-6 inches of fully saturated soil mix weighs between 15-50 pounds per square foot. Consult an architect or structural engineer about structural support and safety if necessary. 


Green Roof DiagramConventional green roof layers in diagram:  
1. Reinforced building support and treated roof deck  

2. Waterproof membrane between protective felt layers 

3. Consider adding a gutter, rain chain and rain barrel to capture runoff 
Conventional green roof Pacific NW planting medium 

  1. Drainage: One inch pumice layer below soil mix 
  2. Soil mix (4-inch depth): 25% organic mix such as TAGRO and compost (provides nutrients); 75% inorganic pumice or shale 

Conventional green roof plants 
Plant with hardy, drought-tolerant perennial plants such as:

  1. sedums
  2. winter heather
  3. Candytuft
  4. Scarlet Beebalm
  5. Heuchera
  6. Rudebeckia
  7. And others


Tree Planting


Right tree, right time!

The ideal time to plant trees and shrubs is during the dormant season the fall after leaf drop or early spring before bud-break. Weather conditions are cool and allow plants to establish roots in the new location before spring rains and summer heat stimulate new top growth. However, trees properly cared for in the nursery or garden center, and given the appropriate care during transport to prevent damage, can be planted throughout 
the growing season.


Wait! Before you plant, did you… 

  1. Select a tree that fits the needs of your site and you (Size, water needs, aesthetics, & etc.)?
  2. Call to have your underground utilities located?

Click here to learn more about proper tree planting and growing in Tacoma.


The City of Tacoma offers a number of tree planting programs and resources throughout the year. Click here for more information from the City of Tacoma Urban Forestry program.


Visit the EnviroHouse to discover more resources, sustainable features, and useful ideas to practice environmental living. For more information or questions, email ehouse@cityoftacoma.org or call (253) 573-2426.