Tag Archives: urban rainwater harvesting

Infrastructure, Rainwater Catchment, Sustainability

Rainwater Harvesting in Urban Areas

brooklyn-street-art-626255_640With so many citizens living in urban areas, cities must approach rainwater harvesting differently than in rural areas, where rain is absorbed into the ground or evaporates.

When it rains in an urban area, rainwater becomes runoff via streets, rooftops and parking lots. Runoff is captured in drains from which it travels via the sewer system, eventually winding up in a lake, creek, or other body of water. Since stormwater is typically released without any pollution management, it can become contaminated with bacteria, heavy metals, nutrients and particulates. So, in the city, water that replenishes our aquifers may have become tainted.

According to Jennifer Drake, Assistant Professor of Civil Engineering at University of Toronto, “Under natural conditions, aquifers are sustained through the infiltration of clean rainwater and streamwater into the ground. But for urban environments, these sources are cut off by the impervious landscapes. Instead, water from leaky sewers, water mains, septic tanks and landscape irrigation becomes the source for groundwater recharge. Since many of these sources are wastewater, they’re poor-quality sources and can lead to groundwater contamination.”

Low Impact Development (LID) includes stormwater management tecniques that allow urban runoff to seep into the ground and evapotranspire into the air. Sustainability systems are built into green roofs (like rooftop gardens), rain gardens (on ground level), which allow stormwater to soak directly into the earth and runoff is naturally filtered by soil as it goes back into the ground and replenishes aquifers.

Read more about Stormwater innovations mean cities don’t just flush rainwater down the drain. The article was also republished via ARCSA.

Rainwater Catchment, Residential Rainwater Collection

Rainwater Collection for Potable Use in an Urban Environment

seattle-skylineSupplementary whole-house use of rainwater in an urban environment is more complex than collecting for potable use in a rural environment. In a rural environment, there is typically more room for storage, allowing the homeowner to store more water than that in an urban setting.

The larger question, however, is – what is landing on my roof and how do I know my collected water will be safe to drink?

In a rural setting, organics are what you need to filter out before the water is to be disinfected and considered potable. A sediment filter, followed by a carbon filter prior to ultraviolet disinfection can achieve this. Bird droppings are the primary concern in this situation.

In an urban environment, other constituents coming in contact with your roof may need to be addressed. Consider where your home is located. Environmental considerations such as automobile and truck emissions can have an impact on your roof runoff and must be removed with proper filtration. Pesticide use is more likely to be encountered in an urban setting than a rural environment. Simple sampling and laboratory testing should be conducted of raw water so proper filtration can be used to eliminate possible contaminants.

Urban potable usage of roof top collected water can be achieved with the proper filtration as with any rural potable system as long as the right filtration is used.

Photo: Julie Gentry

Commercial Rainwater Harvesting, Rainwater Catchment, Residential Rainwater Collection

Rainwater Collection in an Urban Setting

Rainwater Collection in an Urban SettingRainwater collection is becoming increasingly popular for commercial and residential consumers in urban settings, driven largely by centralized water unable to meet demands caused by droughts, increased population, along with supply and demand.

Quality of water is threatened by an aging infrastructure and environmental concerns such as the chemical spill in West Virginia last winter.  Awareness and concerns of fluorides and chlorine in municipal water supplies are adding to the interest of alternate solutions.

Increased costs to meet storm water management and GSI (green storm water infrastructure ) requirements for new construction of commercial and residential projects are driving owners, designers, engineers, and architects to offset some of the costs involved with implementation.

In a recent report by “the National Resources Defense Council” eight cities were studied for potential economic impact of rainwater collection. It is estimated the residents of these cities could save 90 million dollars each year by adopting simple rainwater harvesting techniques.

Water closet and laundry facilities using rainwater collection are now becoming integrated into designs for both commercial and residential application.  According to the American Water Works Association, water closets account for approximately 51% of water usage in commercial buildings and approximately 50 % water usage for water closet and laundry facilities in residential applications.