Everyone living in a rural area should have a working greywater system. Most do not, and many others do not even know what it is. For the record, greywater is all household waste water except sewage/toilet water (better known as black water). It includes water from laundry, dishes and the bath. Because of dangerous fecal contamination, it would not include diaper rinse, or water used in cleaning animal stables, or bath water from someone with a communicable disease. But the line is a fine one. Greywater will usually contain some level of black materials like dead skin, food particles hair saliva, grease, detergents, crap residue , bacteria and chemicals. The question is how much is too much?

Because of the possible dangers, most municipalities do not distinguish between black and grey water. All household wastewater is considered black and must be disposed of in a sewer pipe, septic field or collecting depot. In areas with septic fields only, this puts a tremendous strain on the system. Our wastewater authorities are encouraging the use of septic fields to dispose of greywater, but owners should realize that the life of their field can be greatly prolonged by reducing water input. As an alternative, a simple system can be set up for home use cheaply and easily. Here area few suggestions. 

  • Greywater systems do not work well in crowded areas. If you have only a quarter acre and are surrounded by other homes some other alternative may have to be found. 
  • Greywater is best absorbed and neutralized by living plants. Soil organisms break down organic materials into water soluble plant nutrients. Plant roots take up these nutrients and much of the water as well. The pure water left over seeps down to replenish the aquifer.   As a sensible precaution do not use greywater directly on anything you will eat later like radishes, carrots, potatoes and lettuce. Instead place your outflow in orchards, pasture, and on ornamentals. Lawn watering is acceptable but beware of possible contamination for animals and children. If you prefer a self regulating system, site your outflow on a well drained part of your property well away from streams and neighbors. Dig out a 6’X6” hole and fill with sand to filter and increase absorption. 
  • Filter and strain all greywater to remove the larger particles of food, grease, etc.—compost or feed this to your chickens. Set up a steel drum or wooden box with different layers of materials for additional filtering (see diagram my book pg. 20). Sawdust or woodchips is best for your first layer. Direct the outflow into your leach field—an upside down flower pot with the pipe stuck in the top makes for splash free dispersal.   Dilute with 50% freshwater for best results although this is not always necessary. On well drained sandy soil figure about a half gallon of greywater per week for every square foot of soil—less for hardpan. Keep an eye on things to see how the plants respond.
  • Your ideal system might include a pit lined with plastic and filled with topsoil. Greywater would feed the trees and ornamentals in the pit without leakage into surrounding soil. If you want to get fancy bury some perforated plastic pipe to disperse the filtered water like a septic field. (see my diagrams pg 22 &23) 
  • Keep greywater in pipes or underground as much as possible. Do not spray on plants or hard surfaces as this defuses the water into microscopic droplets, which could spread contaminants. Do not store for more that a day or two or allow to puddle. A thick mulch of hay, wood chips or even cardboard speeds decomposition and provides protection for youngsters and pets.
  • Avoid bleach, fabric softeners, boron, phosphates, ammonia, chemical cleaners, and hot water, as these will damage plants.


Grey & Black Water Usage

Hi to All,

I live on an Island off the coast of Spain called Formentera here we have water cisterns which are fed with rainwater from the houses roofs and areas of stone or cemented collecting surfaces we have no sweet groundwater (except for a few artesian wells,

We use 3 compartments septic tanks... the water that comes out the third compartment can be used to water plants and has very little odor.

You can do this automatically using a 12v flow jet pump conect to an old solar panel without any battery ... it will run when the sunshines.

We use the greywater to flush toilets and water the vineyard we use only biological detergents

we do not use toilet paper and wash shit off our asses with a bidet shower

the septic tank eco system has been working for 40 years without needing to be serviced

Human sanitation systems

I've read your treatise on human waste with interest.
There is a lot of truth there and also a lot of misunderstanding. I am an Environmental Engineer, practicing for over 30 years.
I also have a cabin on an island with no electricity and have worked with Septics, greywater and outhouses.

I would strongly suggest you send your synopsis to a number of practicing engineers for editing.
Its very well thought-out, but there are some misconceptions. I don't pretend to know everything, but I think you need to get some second opinions. The below is just my understanding. Its not perfect.

Isolating your outhouse pit with plastic does not allow water, air and microbes to enter. It will rapidly fill up because it cannot decompose. Bacteria need water. Anaerobic function below the surface without oxygen. Aerobic function at the surface and in the pores of the soil where there are air pockets.
The alternative is to not line it with plastic but dig it deep; every day treat it with enzymes (not lime) diluted in a few of buckets of water. And throw in some surface soil. Of course it must be far away from any lake, stream etc., or drinking well.

The benefits of composting toilets are exaggerated and misleading (to promote sales). Human waste IS compost by itself (without a composting toilet). Its organic matter that has not been digested plus many species of bacteria. It is the biological niche for diseases and therefore must be broken down by bacteria completely. (It does not mean that all human waste contains diseases - its just where they can thrive.)
Pathogens remain active in human waste for months. The composting toilets somewhat accelerate the breakdown of human waste, IF, they are maintained properly. BUT... then you must handle the waste before it is completely broken-down, which I believe is a higher risk than an outhouse.

Greywater: If you clean food waste well, and don't wash it down the sink, Greywater is 99.9 % just water. It does not present a measurable hazard. If you use biodegradable shampoo, soap and dishsoap sparingly, it will rapidly decompose in a greywater pit and in surface soil.
Backing soda is a good alternative to dish soap. It has some abrasive cleaning properties and is quickly converted to CO2 and sodium in the soil which is usually somewhat acidic.

Feel free to check this out with other engineers. I don't have the answer to everything, but there are a lot of misconceptions out there.



Hello Scott Barclay,
Thank you for your input. I completely agree that “isolating your outhouse pit with plastic” is a stupid idea.

Perhaps I was unclear in my chapter A Homemade Composting Toilet, and for that I apologize. I suggested constructing a closed 4X4X4 foot wooden box to be used above ground. Add your humanure with lots of sawdust, grass clippings and/or other organic matter to compost. Cover with plastic to keep out water.

However, I strongly disagree with your claim that shyte needs added moisture and microbes to compost. Isolating your movement from excessive moisture is very important. Too much water is the best way to spread fecal contamination into drinking water. Dumping water into a composting toilet defeats its purpose, and actually prevents the breakdown of organic material. Fresh poo contains more that enough moisture and microbes for composting when additional organic material is added.

I wrote this little pamphlet because people here were trying to put septic tanks into impossible places like swamps and rock bluffs. And those with septic fields had no place to dump their effluent since there is no septic disposal site on Lasqueti Island—so they just dumped it in the backyard. This booklet was designed to provide sensible alternatives in a very rural area.
--Douglas Hamilton