GREEN BUILDING 101: Water Efficiency, Both Inside and Outside the Home
There are few things we take for granted as much as our ability to turn on the tap and get water in a seemingly endless supply. Even during droughts, and despite warnings about shortages and conservation, most of us treat this precious resource as a given. The average American uses 80-100 gallons of water per day, and while less than half of that will be used for cooking or drinking, chances are that all of it is treated, potable water from the municipal provider. What many people don’t realize is that it’s fairly easy to implement systems for recycling and reusing water on your own property, thereby decreasing the demands on shared supplies, and reducing your water bills. Read on for details on the three LEED-Hcriteria for water efficiency at home, plus additional info on wastewater treatment and reuse.
Water Collection and Reuse
If you hate to miss out on a great bargain, look out the window next time it storms to see what you’re passing up—there’s no more cost-effective water source than rain. In fact, if a single thunderstorm drops 1 inch of rain on your yard, you have just watched the equivalent of over 250 bathtubs full of water trickle by!
The first step for increasing water efficiency at home is to reduce the use of drinkable water for non-consumption purposes. There are two ways to do this: collect rainwater, and reuse indoor wash water. You can install cisterns above or below ground that will collect and store run-off from rooftops and other impervious surfaces, as well as water from laundry machines, dishwashers, bathtubs, and sinks. The latter is classified as greywater, meaning that it does not include human waste or sewage.
These collection tanks can then serve as an on-site supply for watering your lawn and garden. It’s also possible to reuse grey water indoors in toilets and for washing, but the regulations and requirements are a bit more complex than for outdoor use. Regardless, there are varying degrees of treatment and filtration that can be installed in conjunction with your cistern, depending on how you intend to use the water
How many times have you seen a sprinkler going full blast on someone’s lawn in the middle of a summer downpour? The irrigation of lawns and gardens consumes up to 50% of the potable water we bring onto our property, and much of that just ends up as runoff, rather than being absorbed by the plants being watered.
This is situation in which technology can be hugely beneficial in conserving natural resources. You can install smart, programmable sprinkler systems and moisture sensors that allow you to measure the amount of water your yard needs at any given time, and control irrigation from a central shut-off valve. Combine this system with your rain and waste water collection and you’ve got your outdoor greenery dialed.
As was pointed out the Green Building 101 installment on Sustainable Sites, it’s wise to choose landscaping elements that are appropriate to the climate and require minimal water. Because of their varying root systems, grass, trees, and flowers all have different water requirements, so when you design your garden, consider the layout of the irrigation system, and try to arrange plants according to the amount of water they need.
*Note: Remember that using water-wise plants for your particular region creates a lower-maintenance, lower-cost garden.
Indoor Water Use
The primary means of reducing indoor water use has to do with the fixtures you choose. Selecting low-flow sink and bathtub faucets, showerheads and toilets can reduce indoor water use by 30-40%. Over the last few years, the quality of low-flow fixtures has increased. Whereas at first they gained a reputation for flushing inefficiently or delivering unsatisfactory water pressure, new products are surpassing the original designs. The other great way to ensure that you are getting maximum water efficiency indoors is to purchase Energy Star appliances, which guarantee a certain degree of water efficiency, and save energy to boot.
Water Treatment Using Nature’s Tools
Because water is so vital, and because the ability to clean and reuse it becomes increasingly important, it’s an area where we’ve seen significant evolution and real innovation over the years. Early building strategies recognized the value on a single slant roof, which allows runoff to be collected in one place. Likewise, gravity obviously supports water pressure, so the higher above ground a storage tank sits, the more efficiently the water will feed out.
Then there is the natural water-filtering ability of plants—a form of bioremediation— which a number of ecologists, scientists and engineers have learned to harness for large scale filtration of contaminated water. Ecologist John Todd devised consolidated ecosystems which treat wastewater and sewage using aquatic plants, fungi, and other organisms. These have generally been used in commercial-scale operations, and not scaled down for residential purposes, or up for city-wide water treatment. But the concept reminds us that our own greenspace can be a filter for the water we waste, making reuse easier.
If you’re a regular reader, you know we take every opportunity to promote green roofs, which are great for utilizing rainwater and diverting it from running offsite. Other rain catchment systems can be devised in the form of botanical facades, and modular permeable pavement. Whatever you can do to make use of rain and wastewater spares your city sewers from an overflow of contaminated water, and keeps your garden verdant and fertile.
We’ll continue this series with materials and resources, so stay tuned!
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