Greywater by Natural Home Building

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Phosphate rich soaps and mild cleaning chemicals in your wastewater (greywater and reuse of washing machine water) are considered pollutants because they accelerate algae growth in the waterways, which in turn leads to oxygen depletion for fish and other marine lifeforms.  

 The beauty of this "problem" is that these same phosphorous, nitrogen, potassium and protein "pollutants" are excellent sources of nutrition when you reuse greywater for irrigation of fruit trees, landscaping, and gardens (planterbeds).

The wastewater your home produces is called effluent and consists of greywater (kitchen, shower, sink, reuse of washing machine water and laundry waste) and blackwater (toilet and garbage disposal waste).  

 The key to a workable, code-compliant, gray water irrigation system is separate plumbing for your blackwater (composting toilet, vault, or septic tank system).  Compared to blackwater, greywater has a very small amount of organic and pathogenic pollutants, so there truly is no need for treatment of graywater in a conventional septic tank.  In fact, your septic tank and leach field are being overworked by mixing graywater and blackwater - the last thing your septic tank needs is bacteria killing soaps and more water from the washing machine.  

 The longer your septic tank (blackwater) has time to settle, the better.   The less germ killing soaps and detergents in your septic tank, the better.   At the very least, your washing machine should be diverted away from the septic tank.   Adding a greywater kit to a new or existing septic system is an excellent way to reduce septic tank pumping frequency.   Please read the beginning of our septic chapter for detailed information on how a conventional settling tank and leach field works.   Greywater settling tanks ("filter basins") work exactly the same as septic tanks - they are just smaller since little or no solids are going into the system.

greywaterdrywellPlease note that even if you don''t have to obtain a building permit for your greywater system now, it doesn''t mean a future owner won''t be required to.   We highly recommend keeping resale value, cost effectiveness, and future health code enforcement firmly in mind when considering graywater irrigation.   Roof run-off cisterns are an excellent source of toilet flushing water should you wish to conserve, but recycling greywater to flush your toilet is simply not cost-effective and is potentially unhealthy.   It is much easier, less expensive, and worlds safer to directly dispose of greywater in a leaching pit or reuse in an irrigation field (planterbed). 

We do not sell systems to reuse greywater for flushing toilets and do not recommend you even consider this expensive, ''high-tech'' answer to a much simpler question.   From an environmental standpoint, the main reason for greywater reuse is to actually reuse the soaps, skin particles, shampoo, and hair conditioner as plant fertilizer, keeping them out of the waterways.   Phosphate rich soaps and mild cleaning chemicals in your wastewater are considered pollutants because they accelerate algae growth in the waterways, which in turn leads to oxygen depletion for fish and other marine life.  

To buy an expensive system, have it installed, dedicate the floor space, and maintain the filters and UV treatment bulbs simply to sterilize greywater and flush your toilet with it is not cost effective nor environmentally conscious.  

What little greywater is produced by the average family is better directly reused for plant growth or simply disposed of back into the aquifer.   At the very least, it makes absolutely no sense to flush the phosphate and bacteria killing soap laden filtered greywater down the toilet and into your septic tank where it disrupts digestive function.   The extreme risk of legal liability is always a consideration for the savvy contractor, homeowner, and your local building officials.  

What happens when the system fails to sterilize the greywater properly and someone gets sick as a result?   Here in the United States, a toilet full of "sterilized" graywater is a lawsuit just waiting to happen; that''s why toilet water reuse systems have never caught on.  

It does not require a vivid imagination to picture a neighbor''s three year old child imitating the family dog and taking a drink out of your toilet, getting infected, and finding you and your contractor in court.  

Stick to a simple direct reuse, non-electric, greywater recycling or disposal system ... avoid high tech storage and toilet flushing greywater schemes.

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