Most of the world's aquifers are being pumped faster than replenished, and all reservoirs are slowly diminishing in capacity as they fill with sediment. At the same time, natural surface waters and groundwaters are being degraded by the wastewater continually dumped into them. Greywater reuse enables you personally to do more with the same amount of water and to increase your water security. At the same time, your greywater reuse reduces the problems of supply and pollution for everyone.
Any greywater system will realize some benefits, but obtaining all the potential benefits is trickier than it seems. Many pitfalls await the unwary. In the average installation, this book will pay for itself many times over in savings on construction, maintenance, and errors avoided.
This book offers underlying design principles as well as design specifics. If you run into a situation not specifically covered, there's a good chance you'll be able to use these general principles to figure it out yourself.
Most of the information otherwise available on greywater comes from vendors. Oasis Design doesn't sell greywater systems, so you don't have to worry that we're steering you toward stuff you don't need. Rather, we make our living by providing information to help people have a higher quality of life with lower environmental impact.
Wishing you the best of luck with your projects,
Art Ludwig
Art Ludwig's day job has been ecological system design for 25 years.
He is the author of Create an Oasis with Greywater and other ecological design how-to books and articles.
He lives with his wife and two children in a cabin surrounded by fruit trees in the mountains above Santa Barbara, California.
Chapter 1: Greywater Basics
First, let's get your feet wet (so to speak)--what is greywater, what can you do with it, why, how, and some greywater lingo.
What Is Greywater?
Any wastewater generated in the home, except water from toilets, is called greywater. Dish, shower, sink, and laundry greywater comprise 50-80% of residential "wastewater." Greywater may be reused for other purposes, especially landscape irrigation.
Toilet-flush water is called blackwater. A few systems that can safely recycle toilet water are included in this book.
Contaminated or difficult-to-handle greywater, such as solids-laden kitchen sink water or water used to launder diapers, I call "dark greywater"; most regulators consider these blackwater. However, the level of pathogens in even the darkest greywater is a small fraction of that in blackwater.
Wastewater without added solids, such as warm-up water from the hot water faucet, reverse-osmosis purifier drain water, or refrigerator compressor drip, is called clearwater.
Reclaimed water is highly treated mixed municipal greywater and blackwater, usually piped to large-volume users such as golf courses via a separate distribution system. It is outside the scope of this book.
What Can You Do with Greywater?
Conventional plumbing systems dispose of greywater via septic tanks or sewers. The many drawbacks of this practice include overloading treatment systems, contaminating natural waters with poorly treated effluent, and high ecological/economic cost.
Greywater reuse follows the same principles that make wild rivers clean...even though they drain many square miles of dirt, worms, and feces. Beneficial bacteria break down nasties into water-soluble plant food, and the plants eat it, leaving pure water. The author is shown here deeply absorbed in his tireless study of this process.
Instead, you can reuse this water. The most common reuse of greywater is for irrigation--the focus of this book. It can also be cascaded to toilet flushing or laundry. Even a greywater disposal system has less negative impact than septic/sewer disposal.
Why Use Greywater?
It is said that there is no such thing as "waste," just misplaced resources. Greywater systems turn "wastewater" and its nutrients into useful resources. Why irrigate with drinking water when most plants thrive on used water containing small bits of compost?
Unlike many ecological stopgap measures, greywater use is part of the fundamental solution to many ecological problems. It will probably remain an essentially unchanged feature of ecological houses in the distant future. The benefits of greywater recycling include:
* Reduced use of freshwater--Greywater can replace freshwater for some uses. This saves money and increases the effective water supply, especially in regions where irrigation is needed. Residential water use, on average, is almost evenly split between indoors and outdoors. Most water used indoors can be reused outdoors for irrigation, achieving the same result with less water diverted from nature.
* Less strain on septic tanks or treatment plants--Greywater, which comprises the majority of the wastewater stream, contains vastly fewer pathogens than blackwater and 90% less nitrogen (a nutrient that is a problematic water pollutant). Reducing a septic system's flow by getting greywater out greatly extends its service life and capacity. For municipal treatment systems, decreased flow means higher treatment effectiveness and lower costs.
* More effective purification--Greywater is purified to a spectacularly high degree in the upper, most biologically active region of the soil. This protects the quality of natural surface and groundwaters. Topsoil is a purification engine many times more powerful than engineered treatment plants, or even in septic systems, which discharge wastewater deeper into the subsoil.
* Feasibility for sites unsuitable for a septic tank--For sites with slow soil percolation or other problems, a greywater system can partially or completely substitute for a costly, over-engineered septic system. (In extreme cases this can enable otherwise undevelopable lots to be built on--a double-edged sword environmentally.)
* Reduced use of energy and chemicals--Due to the reduced amount of freshwater and wastewater that needs pumping and treatment. If you provide your own water or electricity, you'll benefit directly from lessening this burden. Also, processing wastewater in the soil under your fruit trees definitely encourages you to dump fewer toxins down the drain.
* Groundwater recharge--Greywater application in excess of plant needs recharges the natural store of water in the ground. Abundant groundwater keeps springs flowing and trees growing in intervals between rains.
* Reclamation of nutrients--Loss of nutrients through wastewater disposal in rivers or oceans is a subtle but highly significant form of erosion. Reclaiming otherwise wasted nutrients in greywater helps to maintain the land's fertility.
* Increased awareness of, and sensitivity, to natural cycles--The greywater user, by having a reason to pay more attention to the annual progression of the seasons, the circulation of water between the Earth and the sky, and the needs of plants, benefits intangibly but greatly by participating directly in the wise husbandry of vital global nutrient and water cycles.
* Just because--Greywater is relatively harmless and great fun to experiment with. Moreover, life with alternative waste treatment is less expensive and more interesting...
