Greywater or Gray water systems as Components of Alternative Septic Systems for Difficult Sites InspectAPedia® -
Graywater systems as components of alternative septic design
Graywater system products & designs - what is "greywater" and how is greywater salvaged for use in watering lawns, gardens, or for purification as drinking water?
How to install & use graywater systems to conserve water or relieve septic system loading
Comparison of sources of water for household or garden use besides wells ormunicipal water supply: rainwater collection, water condensation systems.
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Greywater is wastewater which does not contain sewage, typically coming from building sinks, showers, and laundry facilities.
Graywater systems can reduce the load on or size of a septic system, and gray water separation, filtration, storage, and
piping systems can conserve water, for recycling for various uses such as flushing toilets, landscaping, or irrigation.
This article describes alternative graywater systems and designs, lists gray water (or grey water) products and suppliers,
and compares products, models, and features.
In addition to explaining graywater systems we list and compare other sources of water for use on lawns, gardens, orchards, or for purification as drinking water. We also include links to greywater system references and books.
Shown here is a clean design for onsite greywater disposal using a sketch from Clivus Multrum (see links below).
Other greywater systems include incineration and alternative greywater disposal methods.
The EcoJohn Jr. shown below at our list of product sources uses a low-flush toilet (not a waterless toilet).
This particular toilet is an incinerating unit not a composting toilet.
Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved
to the author. Technical review by industry experts has been performed and is ongoing - reviewers welcomed and are listed at "References."
What is Greywater or Graywater and What is Blackwater?
"Greywater Septic Systems" refer to onsite wastewater systems which reduce
the liquid effluent load on a septic system by separating greywater (or graywater) from sinks and showers from
blackwater (black water from toilets.
When we inspect a home which uses a separate drywell to handle greywater
we presume that the owners discovered that their septic system, or at least its leach field, was of limited capacity
or life.
Gray water systems may also be used to conserve and recycle water in areas of limited water supply.
The graywater filter basin and graywater filter shown above are discussed at SEPTIC & GREYWATER FILTERS
Gray water is usually water from building drains other than toilets, such as
water from a laundry system, sink, or shower, and effluent from sump pumps.
Other site gray water (or greywater) which is sometimes preserved and used
at a building includes rainwater or roof runoff. Some writers include groundwater in the
greywater category. I disagree, though greywater disposal systems may benefit the environment
by replenishing groundwater.
Greywater does not contain human waste products. Therefore when it is disposed-of on-site,
it does not need to be treated to the same extent as is required for sewage or "black water".
In fact, soil filtration and soil biomat treatment of greywater can produce very clean water for
ultimate discharge into the environment.
Therefore building code requirements for on-site disposal of grey water are less strict.
However in most jurisdictions it is illegal to simply dispose of greywater by dumping it
on the ground surface. Some treatment and filtering such as that provided by a drywell will be required.
For building sites where there is limited space for septic "black water" disposal and treatment,
one can install piping and equipment separate the gray water from black water (human waste) - a
step which reduces the needed size of the septic system. (Space will still be needed for
graywater handling).
A second reason that some property owners install graywater handling systems is a shortage
of potable water or the need to conserve and recycle water for re-use.
In dry areas where there are limitations on the water supply, filtering and
treating graywater can permit its use for watering lawns or crops as well as for flushing toilets.
This approach serves two goals,
both disposing of onsite graywater and supplying water for crops or shrubs.
A typical graywater system can save 50 to 100 gallons of water a day, or even more, depending on
the level and types of water usage in a building. Even homes connected to a municipal water supply benefit
from a gray water system as by recycling water for re-use the building owners save on their water bill.
The following sample greywater system specification is from:
New York State Appendix 75-A.10 Other systems. Other
U.S. state's laws and specifications regulating greywater systems are listed below.
(5) Greywater Systems
Greywater [grey water, gray water] systems shall be designed upon a flow of 75 gpd/bedroom and meet all the criteria previously discussed for treatment of household wastewater.
[DF NOTE: Grey water is water that does not include sewage, including water from sinks, showers, and laundry facilities.]
Types of Graywater Products and Systems
Here we outline a variety graywater products, systems, and designs used to conserve water, re-use or recycle water, reduce water use, or to store and re-use graywater. Links to in-depth articles about these products and systems are provided below. See WATER SOURCE ALTERNATIVES for details.
Cisterns have been used since prehistoric time to collect and store rain water or water from other sources.
Modern cistern systems use concrete tanks, steel, fiberglass, plastic, or site built tanks to store water for
re-use. See WELLS CISTERNS & SPRINGS.
Composting Toilets reduce water consumption by using little or no water from the building water supply. See TOILET ALTERNATIVES and Composting Toilets.
Drywells are used to dispose of un-wanted graywater on-site. There is no provision for water storage
or water re-use. See Drywells.
Filters for Greywater are installed at a laundry sink, clothes washer, or at the outlet of
a wastewater tank to filter water for re-use. See Filters for Septic Tanks & Graywater to protect septic drainfields and reduce drainfield clogging.
Graywater Irrigation Systems or drip irrigation systems make use of (usually filtered) greywater
to provide water to lawns, plants, or crops. See Greywater Septic Systems.
Low Water Toilets or Low Flush Toilets conserve water by using only a small amount of water to achieve
the flush cycle. Low-Water or Low-Flush toilets work well partnered with graywater systems to both conserve and
re-use water. See TOILET ALTERNATIVES.
Rainwater Collection Systems provide alternative water supply for use in flushing toilets or
irrigating crops, lawns, or plants. Rainwater collection relieves the load on the potable water supply whether it's from a
local well or from municipal supply piping. Rainwater collection systems range from a simple "rain barrel" to collect
roof runoff, to very large cisterns which store water for onsite use during dry seasons or droughts. Examples are at PASSIVE SOLAR HOME, LOW COST.
Waterless Toilets conserve water by using no water to achieve
the toilet flush cycle. Like composting toilets (see above), waterless toilets work well partnered with
graywater systems to conserve water. Waterless toilets include incinerating toilet models (see links at page left
for more about alternative toilet products & designs.) See TOILET ALTERNATIVES.
List of Sources for Graywater Products, Systems, Designs, and Model Comparisons
Books and Design Specifications For Graywater Systems:
Create An Oasis with Greywater, Art Ludwig. Also see Ludwig's "Branched Drain Greywater Systems" and his "Building Professional's Greywater Guide".
Greywater Recycling Kigs & Equipment from The Natural Home Building Source: http://www.thenaturalhome.com/greywater.html
Graywater Central - online web with design information http://www.graywater.net/
Arizona: Graywater Law and Designs:
California: Graywater System Standards: www.owue.water.ca.gov/docs/Revised_Graywater_Standards.pdf
Colorado: Graywater Design Suggestions: water.state.co.us/pubs/policies/waterharvesting.pdf discusses rainwater harvesting and graywater systems in Colorado
New Mexico Graywater Law and Designs
Utah: Grayter Systems Design Standards: www.rules.utah.gov/publicat/code/r317/r317-401.htm
Eco John describes two incinerating toilet models: EcoJohn Sr - "A highly efficient, waterless toilet that incinerates the waste with propane.
This is a toilet that is ideal for cabins, pool houses, guest rooms, or other remote areas where a conventional toilet is not available or too costly to install."
and EcoJohn Jr Pr1 System "This is a new revolutionary system that incinerates gray/black water from a holding tank. This system is perfect in areas where a water toilet is needed, but pumping out the waste is problematic or too costly." This grey water and waterless toilet system that includes an incinerator for
graywater that marries with a low-water toilet, the the EcoJohn Jr
which is includes a sewage and graywater incinerating unit. The EcoJohn Jr. uses a low-flush toilet (not a waterless toilet). This is an incinerating unit not a composting toilet and not a chemical toilet system.
Clivus Multrum greywater systems use a holding chamber, effluent pump,
and an onsite irrigation chamber (see our Gravelless septic system components information) to dispose of graywater.
The sketch
of a greywater handling and disposal system shown here is from the Clivus Multrum website where more details of system operation are provided.
Where soil conditions and site space permit
onsite graywater disposal this system design can significantly reduce the wastewater load on the septic or "blackwater" system.
Clivus Multrum has long experience with composting toilets (CM was an early designer of composting toilets) and greywater disposal
systems.
Contact Us to list your product or service here - if you are
a manufacturer of composting toilets or other alternative wastewater treatment system equipment your product
may be listed at no fee. Website content critique, additions, and suggestions are also invited.
Rainwater Collection Methods to Obtain Additional Water Supply
You may find that you are better off providing a large cistern type storage tank. Use of large water storage cisterns has been a common practice for thousands of years and continues in modern use with plastic or fiberglass water storage tanks into which rainwater or in some areas even surface runoff may be channeled for future use.
See the rainwater collection and storasge tank we show in our article at PASSIVE SOLAR HOME, LOW COST) and collecting as much rainwater as possible when rainy weather occurs.
Graywater Collection Methods to Obtain Additional Water Supply
What most people do, as you will see in our article above, is make use of graywater, usually filtered, sometimes treated.
You might find that rainwater collection in areas where rainfall is plentiful in some seasons, or graywater use, are more economical for your use, and that condensation is more costly to operate and less productive in quantity unless you design a cheap, very large solar condensing operation.
See SEPTIC & GREYWATER FILTERS for graywater filters used to protect septic systems from debris in graywater, the first step in making graywater useful for watering grass, trees, plants, etc.
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Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Alan Carson Carson Dunlop Associates, Toronto, Ontario. Mr. Carson is a home inspection professional, educator, researcher, writer, and a principal of Carson Dunlop Associates, a Toronto home inspection and education firm. Mr. Carson is a past president of ASHI, the American Society of Home Inspectors
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06
Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com 11/06
Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. 11/29/06
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and
Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by
Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)
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