Tag Archives: stormwater runoff

Environmental Benefits to Rainwater Harvesting

woman in rain-756647_640Whether it is a small rain barrel garden system or the largest commercial irrigation system, there are many environmental benefits to rainwater harvesting.

Here in the Pacific Northwest we have a climate that sustains and nurtures our forests, lakes, rivers, and lifestyles. Often we grumble a little about the long dreary rainy days of autumn and winter, dreaming of summer months of enjoyment and recreation that our beautiful state offers. It is the rain that feeds our mountains with snow, keeps our rivers and lakes full, our forests green, our air clean, and our water supplies replenished. We are fortunate to live where the climatic conditions offer a seemingly never ending supply. and never give it much thought. Water from oceans, lakes, rivers turn into water vapor during evaporation, then condensate into droplets that form clouds. As the clouds become heavy they lose their water through rain or snow and the cycle starts over again. Protecting the cycle of water with sustainable, environmental practices and conservation will help ensure our water supplies for future generations. 

What if we interrupted that cycle for a moment? Borrow that water briefly? Then, return it to the natural cycle without a lot of energy. Rainwater harvesting does just that by on site collection, storage and use returning it through infiltration.  Rainwater harvesting:

CONSERVES WATER : 50 – 70 % household use is used for landscaping. It does not need to be treated to drinking water standards.

CONSERVES ENERGY: Rainwater collection bypasses a centralized system, conserving energy.

PREVENTS FLOODING & EROSION: Less stormwater to manage by diverting it to storage, then usage.

DECREASES WATER CONTAMINATION: Limiting runoff which pick up contaminants as surface water.

REPLENISHES AQUIFERS:  Washington State Ecology determined that in stream flow rates and Aquifers benefitted from rainwater collection and infiltration.

Other benefits include lower monthly water bills, provides naturally soft water, use of less detergents and soaps. If properly filtered and disinfected, rainwater can be used for whole house demands including drinking water, free of chlorine and other additives used in municipal water supplies. Rainwater collection can be a practical answer to storm water and drainage codes, allowing for mitigation of the roof area as an impervious surface. 

So when it rains here in Seattle, look at it as a gift – a gift that we can pay forward by common sense stewardship of this life sustaining resource.  

Why Water Lifecycle Matters

watercycle-kids-screenAn informative, fun and interactive diagram jointly developed by The U.S. Geological Survey (USGS) and the Food and Agriculture Organization of the United Nations (FAO) outlines an easy to follow water-cycle diagram for schools.

RainBank has previously discussed this phenomenon, in an article from May 2015:

The continual movement of rainfall from the bodies of water, land, and the atmosphere is part of the hydrologic cycle.

The cycle starts with condensation. When water vapor condenses in the atmosphere it forms clouds, when the condensation becomes too heavy rain is formed and the clouds release the rain.

water lifecycleWhen rainfall reaches the surface it infiltrates into the soil, becoming groundwater. The infiltrated groundwater recharges our aquifers, rivers and lakes. Water that runs off the surface is referred to as stormwater.  Water is returned to the atmosphere through evaporation by the sun heating the water, changing it to a gas and it rises into the atmosphere and becomes vapor again.

Depending on soil conditions, the movement of stormwater across the surface can cause erosion and also carry pollutants into our bodies of water. This is why stormwater management is so important. Stormwater management practices such as infiltration, or collection, slow down the process of surface water runoff and helps keep erosion to a minimum. Much of the pollutants associated with stormwater runoff are not carried to our larger bodies of water – keeping our natural environment healthy.

It is important to have a basic understanding of water’s lifecycle in order to fully capture the meaning of why rainwater collection is so important to having a sustainable future.

Climate Change and Water Scarcity

ball-1055956_640At the Paris World Climate Summit held in December 2015, participants overwhelmingly agreed to work on a legally binding agreement to reduce carbon output as soon as possible. While currently non-binding, there is commitment to “do their best to reduce their carbon output”.  Global warming is expected to account for approximately 20% increase in water scarcity this century.

According to the Natural Resources Defense Council (NRDC), “Climate change will have significant impact on the sustainability of water supplies in the coming decades.”

The Federal Clean Water Needs Survey identified over $100 billion in needed infrastructure in the next 20 years to address stormwater and sewage overflows.

The NRDC goes on to explain that capturing rainwater from rooftops is an effective water resource management strategy that increases supply and reduces pollution.

The unnecessary use of potable water for non-potable uses, such as outdoor landscape irrigation and indoor toilet flushing, climate change and continually increasing areas of impervious surfaces in our landscape, results in stormwater runoff carrying pollution to our rivers, lakes, and beaches. Although the problems of water supply and water pollution can be complex, practical solutions for both are available now, such as capturing and using rainwater from rooftops.

Rooftop rainwater capture is a simple, cost-effective approach for supplying water that promotes sustainable water management. Reusing rainwater, rather than allowing it to run off of paved surfaces to pick up pollutants and carry them to nearby surface waters, is a practice which provides numerous benefits:

  • Inexpensive, on-site supply of water that can be used for outdoor non-potable uses with little, if any, treatment, or for a variety of additional uses including potable supply with appropriately higher levels of treatment
  • Reduced (or no) energy and economic costs associated with treating and delivering potable water to end users because capture systems often use low-volume, non-pressurized, gravity fed systems or require only the use of a low power pump for supply
  • Reduced strain on existing water supply sources
  • Reduced runoff that would otherwise contribute to stormwater flows, a leading cause of surface water pollution and urban flooding.

Seattle has adopted “Rooftops to Rivers” strategies for controlling storm water and combined sewer overflows. Updated code and regulations can be found here.