Why have a Grey Water **system**?

I'm no expert... but I have been looking about the web, and see tons of grey water *systems*... tanks, pumps, valves, switches, and on and on and on.  But it seems to me that the secret of grey water use is getting it in to the ground as fast as you can, and letting nature do it's thing.

Am I wrong about this?

It seems to me that the best thing to do is to make a trench... shallower at the input end.... and deeper on the other end (so water can flow)... fill it with wood chips... perhaps cover that with soil to "seal it up", and then run grey directly into it... planting to the left and right of the trench.  I guess I just don't get why people are so keen on holding tanks, strainers, switches... why do all that?

What am I missing?

Thank you!

r

Hi Ryder.  If nobody has done so thus far, I will welcome you to Permies, right now.    Welcome!  

You are right to question what you see as over-complicating a simple thing.  It's good to ask questions.

I guess I just don't get why people are so keen on holding tanks, strainers, switches... why do all that?

What am I missing?

I don't think you are missing anything with that question.  None of that is really necessary, the way I see it, but some of those things might be necessary depending on the needs or desires of the person and his or her landscape; but I will have to clarify what I mean.  I think you are right to question the over-complication of these things, and that the simpler the system is, the simpler it is to build, maintain, and generally deal with into the future.

When you write:

the secret of grey water use is getting it in to the ground as fast as you can, and letting nature do it's thing.  

 I have to respond: Maybe.  But it might not be getting the best use out of it.  Without a really good biological system already in place, a trench of this nature can create an anaerobic slime seal and back up on itself, or (in an area like mine) can get penetrated by a deep frost, stopping flow.  

My guess as to why this (want to build systems) is so, and why people are apt to not simply build a trench and plant around it ( which might be fine for most people's needs )  is that there is a thing that we tend to want to do in permaculture where we try to get the most out of something before we potentially lose it from our system.  We use water, for instance, as many times as we can, before it eventually finds it's way off the property; the same for flows of nutrients.  When someone develops a gray water system, the purpose, as far as my thinking goes, is to try to get the most out of the nutrients, and the water, before it can leach into the groundwater system (which it has the potential to do in a sloped trench-especially in winter in cold regions).

My own plan is to have my gray water dump directly from an open vented pipe into a basin of large stones, which will draw out the possible heat from a hot shower so that the heat doesn't harm the roots of plants or the microbes that will do the magic shortly thereafter.  The large stones would be surrounded by deep mulch bottomed by stones and sand (with much of the mulch well over the depth of water flow) in which I am growing comfrey and mint and maybe other plants.  These will be good plants for wet areas, and will also provide good habitat for earth worms, which will thrive in the microbial rich mulch that is straining the liquids..  I can take chop and drop from the comfrey to place on top of the compost area, which is right after the mulch, direct soak nutrient filter area and this is where the compost worms are; they further take on the task of transforming the nutrient flow into something useful.  The water flows through the system, before it leaves the house, possibly growing edible herbs and salad stuff in deep mulch still in the house.  After leaving the house, the plan is to have the water go to a greenhouse downslope of the house, where the still nutrient rich gray water will be filtered through a flow system of deep mulch and mud with cattails, bulrushes, horsetails, nettles, mint, yarrow, and maybe a few more plants.  At this point, I am hoping that the majority of the water has been turned to plant matter (all of which can be harvested for quality compost materials for soil building in the garden).  There is a possibility that this second stage of the system might also be incorporated inside the house, as they do in advanced Earthships.  By this time, if there is water left, it will be clean enough to have it drop a gold fish tank.  At any rate, my system is designed to get the gray water into the plant systems, and soil building systems as soon as possible and to utilize it in it's entirety so that it does not get into the ground water system.  In my case, preventing the system from freezing is also paramount.  I do not want to build a septic system at all.  My personal wastes (that would normally create black water) will be composted.  

The intention is to close the loop, and Return The Surpluses back into the System.  This is the third Ethic of Permculture, after Earth Care and People Care.  

I agree that the simpler that this task can be achieved the better, as it would be a waste of resources to have it be otherwise.  I see no need for tanks, pumps, valves, switches; but I have the benefit of a slope, and the gravity that effects things on it.  The Earth and plants do the filtering, but I control how that happens, and I try to get the most out of it, and possibly pretty much all of it.  

I hope that answer was not overly complicated.

I just wanted you to get a firm grasp of where my brain was at, so that you can see a rationalized expression of the need for a system.

Well it sure sounds like you are doing all you can to simplify it!

In my case, I'm in California, and freezing is not ever going to be an issue.

I am also not intending to absolutely maximize usage... I was thinking about essentially irrigating a planter box (from my tiny house... which produces very little waste water... and NO black water).

I thought I could start high in one side of the planter... with soil/mulch layers at a sloping angle, possibly a liner in the planter that is also not flat (angled)... then at the opposite end of the planter, move the water into a trench with more mulch and have it serpentine around a few young trees.

You do bring up a good concern though... something about an "anaerobic slime seal" which I don't know exactly what that is... but I can picture what it must be like.  So I guess some thought must be given to preventing blockages... and in this case you are implicating a lack of air.  I guess that is why I mentioned just passing it though mulch (just something I've heard being used a lot).  For the most simple gravity flow situation... how does one plan to avoid such a blockage?  I assume with providing for the right biology, yes?

Thank you for your detailed answer!

You do bring up a good concern though... something about an "anaerobic slime seal" which I don't know exactly what that is... but I can picture what it must be like.  So I guess some thought must be given to preventing blockages... and in this case you are implicating a lack of air.  I guess that is why I mentioned just passing it though mulch (just something I've heard being used a lot).  For the most simple gravity flow situation... how does one plan to avoid such a blockage?  I assume with providing for the right biology, yes?

What is often done in situations/projects like you are describing is to have your exit pipe open up in your trench under something that amounts to a half barrel, cut from top to bottom. The open cut flat edges side faces down, and the half round side without edges faces up.  Some people use plastic for this barrel.  It lasts longer underground.  They actually sell something designed for this purpose.   The purpose of the barrel is twofold: To keep tree roots out (via air pruning) and to provide air.  The best thing that you can do, beyond that is to get worms active in your trench.  They will provide drainage and will consume microbes (both anaerobic and aerobic), creating humus which will allow most of the nutrients and the water to be held in the soil systems/be available to plants.  

Well it sure sounds like you are doing all you can to simplify it!  

  Well, not simple, but without all the technology that you mentioned.  Simple in that the pipe just drops it in, and simple that I am still direct as soon as possible to plants.

Different goals and/or legal requirements.

The international Building Code has some requirements for grey water systems like filters, grease traps, settling tanks, valves to switch it back to black water system, etc.

In other cases people have different goals.  If all you want to do is get rid of the grey water, then a simple trench can be effective.  Some people have existing landscape, or specific plans for landscape that require more complicated "branched drain" systems to distribute the grey water to multiple locations.

Generally speaking a grey water system should be as simple as possible to meet your goals.

Then you have people like me that have a desire to stop depleting the water table and switch to using only rain water.  Unfortunately, we tend to get 75-100% of our annual rainfall in just 2-3 months. While storing enough rainwater for the entire year is possible, it's cheaper and uses less resources to clean up a portion of our grey water and store it for a couple months when needed.

I use a hose to move my greywater from place to place. This minimizes buildup in any one spot. I find the hose easier to clean than a fixed pipe system. Of course, it does require more attention. I have to move the hose, and empty the dregs.

I think the true secret of gray water system is knowing and using proper products going into it.

The reasons laws and regulations require so much from grey water systems is that in a typical home, it is probable that chlorine bleach, ammonia, and acids make their way into the system, not to mention paints, solvents and grease. It might be as innocent as diesel fuel being spilled on a jacket while filling a farm tractor and then being laundered, or as environmentally abusive as dumping paint down a utility sink so that the can itself can be disposed in a dumpster somewhere.

Most of us that have gray water systems that get diverted to better uses then simply filling up our black water tanks, are VERY diligent on what gets put into the system. In short we are ethical and responsible; no system required. However from a governmental point of view, what if that person sells their home to a less environmentally desirable person, or the residence is existing 100 years after that persons demise?

You are indeed right, a one pipe trench system is completely adequate, but my inlaws who lived on a major river in New Hampshire can also remember seeing bubbles in the river about 20 minutes before their neighbor hung laundry up on the clothesline.

In my own town, the Maine Dept of Environmental Protection made an outrageous claim that our local lake was polluted by farmers. It was impossible, we only have 10% of the land base here as farmland. So the local Soil and Water Conservation District hired divers to enter the lake knowing the cause of pollution. They only had to follow a few pipes back to houses along the lake to make their point, farmers were NOT to blame. These former camps were converted to year around homes and thus they just tapped into the former gray water systems to save building expensive leach fields; yes they were dumping black water (human waste) into the lake!

My state law dictates a lot of what you are describing as unneeded.

No puddling of gray water and no discharge of gray water when puddles exist (dont discharge in the rain). We are required to have tanks that hold 3 days worth of graywater.

So a valve is needed to prevent the discharge during rain.

A pipe is needed to get it underground.

A back water valve (back flow preventer) is also needed.

Hello folks, I hope people will see this message even though it's at the end of an oldish thread...
My husband and I are building a house in an urban area of southern Mexico. We want to make it as sustainable as possible and have hired earth-builder specialist archictects... but they're a bit on the young side and I sometimes wonder if they've thought through all the options. Perhaps the Permies hive-mind can help.
Our plot is 300 m2, (ca 11 m wide by 24 m long) on a steep slope downhill from the road. The house (foundations already in place) will have two levels, "staggered" to fit the slope. We've built a 30 m3 (30,000 liters) ferroconcrete rainwater catchment cistern at the bottom of the plot, with a smaller (5000 l?) separate cistern for using (scarce) neighbourhood mains water when the rainwater runs out in the dry season (6 months in winter). Because the cisterns are 5 m below the bedrooms, for our water use, we'll need to pump water from the cisterns into a plastic tank (known here as tinacos) in a "tower" above the bedrooms and upstairs bathroom, to get enough water pressure in the shower. The house sits towards the bottom end of the plot, with a chnk of steeply terraced garden above, and a patch of space at the base - a 1m-wide strip of space between the cisterns and the house.

The current grey- and blackwater plan is as follows:

- Greywater will come from the kitchen, shower, washing machine, sinks.
- We'll have one dry composting toilet (separating pee and poo) on the ground floor where we hope to do most of our "contributions of biomass". Poo falls into drums stored in a chamber under the toilet (where we'll let them decompose in peace and haul the compost out to a plot in the countryside, or on the fruit trees), pee goes through a tube into its own little soakaway.  
- The complication comes from the upstairs toilet next to the bedrooms. We'll probably use this mostly for night- and morning pee, but because it's on the second floor we couldn't work out how to make it a dry toilet. (We also think that if we want to sell the house later, the lack of a WC might put buyers off.) So this pee will go into water, which will join the greywater, turning it into pee-water. (we can put in a "popbox" upstairs to poo in a bucket and cover with decomposed sawdust and ashes - we already do that in our rented house.)  
- The greywater + upstairs pee-water is destined for a ready-made biodigester with 300 l capacity. The water coming out of this will be directed into a soakaway ("pozo de absorción") in the downhill corner of the plot. The builders say that it will be a massive engineering project, 4 m deep, made of breezeblocks, concrete, etc, very expensive... that sounded surprising.
So what's the view of Permies?

Costraints:
- We don't have physical space for another cistern for the treated greywater coming out of the biodigestor (which could be used for irrigation).
- The downhill corner where we're planning the soakaway pit is itself right above to the downhill neighbours' property and on the uphill side of a 2m retaining wall - structural issues! The neighbours haven't built anything there yet, it's fruit trees and rubble, but who knows in future. Otherwise we'd be very happy to plant one of those banana grove things.
- In the rainy season (May to September) it also rains heavily every day, so we need a way to drain the rain that falls on our plot (although the water that falls on the roof will go into the catchment tanks).
- At the moment we're not planning to connect to municipal sewerage at all, because those pipes are at street level, five meters above our house, and we'd need another pump.

Building codes here are subject to a gleeful anarchy which we hope will let us get away with unorthodox solutions.
I'd be grateful for suggestions!

Why cant you separate the urine from the solids upstairs and run a dry toilet upstairs. The urine can be piped to the the same soakaway?
The other aspect is as you suggest the next door block and its future use. It needs to be respected.
How big is your house compared with the plot?

For simplicity’s sake what about a banana circle? I know you guys at a more northern latitude couldn’t but most of us could. There are varieties that are hardy to -10 Fahrenheit. My neighbor wanted some for a sitting area so I bought him five plants two years ago. They were ten dollars a piece at Lowe’s. They were a couple feet tall and but now around seven.

Hello folks! Because of the salmonella risk here we decided to direct the (potentially black- and) grey water from the biodigestor into a soakaway pit, 4 m deep and loosely filled with layers of gravel, sand and charcoal. The architects also made the case for letting this water replenish the aquifer... Next year I can let you know how well it works!

Consider placing vegetation that will transpiure some of the water.
I would be concerned about letting it soak to the ground water aquifer though.

You will need to "work closely" with the contractors if you hope to get anything close to what you plan. Way of life, but particularly with young "gung ho" contractors.

What _is_ the aquafer situation?

What is the soil and subsoil? Percolation?

What happens now at the lower corner when it rains? Why did the retaining wall get built? How long has it been there and does it show erosion around it? How is it made? To the extent you can find the  "spec's" for that wall, you'll be in a much better position to plan and possibly avoid difficulties in the medium time frame. In the absence of functioning building codes there is _nothing_ you can assume about any structure you come across. Boundaries are always points of involvement with neighbors, so it helps to know what may be coming down the road.

Keeping rainfall runoff on the property and encouraging it into the ground as quickly a s possible (ie. before it runs to the bottom of your property) would seem best. This can protect your foundations as well as bettering your growing environment and reduce issues at your lower property line.


Regards,
Rufus