greywater moat??

I'm beginning to think I have jumped off the deep end here but ... we want to build a moat around the outside edge of our property to handle our greywater. Essentially it would be just like a pond but longer and narrower. We were thinking we could maybe use the dirt from it to build huglekulture berms on the farm side of the moat to help with noise reduction from a noisy gravel road and plant reed and cane and other water plants in the moat/along the berm to help with remediation of the water as it flows through. We have a creek on our property and the moat would run over 400 feet through filtering plants, etc before entering the creek. Or maybe we could have a secondary catchment pond to catch the run-off from the moat and then go to the creek?

I don't want to hurt the environment, obviously, but I also don't want a septic pit in the middle of usable land nor a huge catchment pond that I have to keep animals out of. The moat would run along the north and east of our property and dump into a wash area from the road and then into the creek as it leaves our land. The berm would then form a "wall" along the two exposed sides of the farm that we could plant on and/or build a solid fence on top of to control noise and privacy.

Any thoughts? Anyone done anything similar?

Generally, you don't want to leave greywater standing in a pond, even a long narrow pond. It should be soaking into the soil rather rapidly, or being filtered through something.

Do you get a lot of rain, or do you just end up with a lot of greywater?

I know that rules vary, but around here, greywater should never leave your property and/or enter waterways without filtration.

It sounds like you are thinking something along the lines of a reed filtration system like this site HERE has advice on Well they are trying to sell it to you, but as it's UK based, a bit far to go! They give sewage treetment systems a 5-15 year lifespan due to the solids but I would think that one just for graywater would last a lot longer.

Already mentioned above; standing grey water is a bad idea. You will get a nasty smelly mess. Greywater systems usually depend rapidly sinking the greywater into the root zone of water plants like reeds. The reeds oxygenate the area and make a substrate for beneficial bacteria to live and break down the nasties. There are many plans for grey water reedbed systems out there, but in generally they do not have standing water. That said, I see no reason why your water couldn't flow into a pond once it has been through the reed beds. Particularly if you placed it such that it got additional rainwater directed to it .

I think it's actually OK as long as there are growing plants, but the problem is winter.

I think decomposition of organic particulates in the grey water will cause oxygen deficiency in the moat, unless some care is taken to oxygenate it from the beginning.

I like the idea of putting alternating bump-outs in straight, long runs of water I want to clean with a reed bed system, such that the water is forced to zig-zag within its channel, increasing surface area and duration of contact with the filtering plant life. This also slows the rate of flow and causes particulates to settle out of the water.

-CK

You might do some research on "Constructed Wetlands"  specifically horizontal, subsurface flow, constructed wetlands.


It's basically a moat like you described, but filled with gravel and plants (reeds, cattails, etc.).  The water surface is typically 3 inches (75 mm) below the surface of the gravel.  Because of the gravel you don't have problems with mosquitos breading in the water, or animals drinking it, etc.  and the plants help clean the water up.  They are typically 20" (50 cm) deep, and contained about 10 CF of gravel for every gallon of grey water you produce per day, although larger is fine, especially if you live somewhere with cold (freezing) winters.

So if your's was 400 feet long and 2 feet wide it could handle 75 gallons of grey water a day.  I'd probably make it 3-4 wide and a bit shorter, maybe run some drain pipe so you can start it at least 30-50 feet from the house.  Constructed wetlands aren't supposed to smell (normally) but why take a chance?

Ok. So reading all the replies so far and perusing the web site offered ... one, this won't have toilet use in it so it's not really a septic field with multiple aerated ponds needed. But, I think, I need perhaps an initial sediment filter as it runs out of the house to catch gunk then a settling pond filled with gravel and reeds and then it could flow into the long "moat" also filled with reeds and other plants where it mixes with rainwater and can be reabsorbed slowly back into the ground or used to water trees, lawn, etc ...

So is it feasible to build a sediment sand filter to remove hair, skin flakes, bits of food waste that might be in this greywater? Would that even work on gravity? And would it help to remove some of the soaps that will be in the water as well?

Also what makes the best plants/reeds for this type of system? Cat tails? River cane? water hyacinth(summer only)?

Thanks for the help!

Greetings,

Just a couple of quick questions, as I have a laundry to landscape system with a surge water barrel.  It works very well for my use, and have been following this but am confused about the quantity of water you are producing.  

So...

How much water and from what sources?

Is there a reason you are looking to (Not trying to be a jerk, but just interested.) make this a big project, vs. something smaller scale and easier to maintain?

Why do you want to filter out the skin flakes, etc?  They will break down and part of the beauty of using greywater, is not needing to filter and clean it.

Have you looked through any of the greywater book for plans and schematics?

http://oasisdesign.net/greywater/laundry/

Happy trails,

Keith

I hate to contradict most of the posters but it's black water that smells. Gray water has very little organic matter in it. The truth is a moat around your property would have very little gray water in it. I'd be surprised if 1% of the water volume ended up being gray water. At most you're talking a few hundred gallons a day and even a small moat would probably have hundreds of thousands of gallons of water in it. A large one could be in the millions of gallons. A one acre pond will have a million plus gallons of water. If you want to quickly figure out your water volume use one of my favorite sites calculator soup and enter the diameter of your property and the depth you want. Now subtract the width you expect your moat and run the calculator again. Now subtract the second number from the first and you'll have the water volume. The water plants are the critical part. I'd set up a feeder body of water so the water plants get to filter out the organic matter before it gets to the moat. Yes you don;t want the water to be stagnant but slow moving is okay. Feed your roof run off into the feeder pond will help keep things moving but honestly unless you're running a meat packing plant and running the waste water into it I wouldn't worry about smell and bacteria. Water plants are amazing at removing organic matter and even if you have a disposal, which you don;t normally have feed into a gray water system, you;re talking at most a pound or two of organic matter a day. True gray water you're mostly talking soap and dead skin cells and what ever dirt you're trying to wash off your hands. Use organic soap and don;t sweat it. Now if we're talking a blackwater system that's a whole 'nother animal and I don't recommend those above ground. For that it's best to set up a modified drain field and just plant a lot of bushes and trees. The trees will think they died and went to heaven and they'll be the biggest and greenest on your property and they'll keep the waste from getting into the ground water if designed properly.

https://www.calculatorsoup.com/calculators/construction/tank.php

I have a laundry to landscape greywater system, and let me assure you, if the water sits out, it smells. My system is very simple, the washer water drains into a large garbage can that has a hose attached, but there is always a little bit in the bottom that I have to manually drain. If I delay this, it stinks, and bacteria grows.

My greywater volume is low, and my climate is dry, so it always absorbs into the soil rapidly. That's why I asked about his volume of greywater.

The sediment sand trap you mention could be something like a barrel half full of sand with a hole in the bottom (use some kind of fabric/mesh/filter to keep the sand in.  Have the grey water empty into the top of the barrel.  Have the barrel empty into a gravel bed planted with reeds to biomediate and filter the water, absorbing excess nutrients (I think, from what I've read, reeds are even better than cattails at oxygenating their root system.  Have the gravel bed empty (from a higher to a lower level)into the moat.  I think it's quite doable, although I think you'll probably need more input than simply house grey water.  Reed harvest would be a product.  Periodically scoop the lint, food bits (from dirty dishes), etc of the top of the sand trap.  Mark the side, some sand my gradually migrate out no matter what you do, if the sand retreats too low below the mark, add a bag of sand.

Most of the reed bed filtration stuff I've read was designed for black water.  A grey water system should be able to handle an order of magnetude more water.

I love the idea of a reed filtration bed feeding a moat, it provides a pond with far more shorline than a roundish pond, therefore probably able to support more life.  It sounds like a LOT of eartmoving though.

I would be carefull about introducing cattails or reeds into a pond.  I think they would take over a long thin pond very quickly (lots of shoreline to spread along).  It was thought that Typha x glauca, a hybrid produced sterile seed and spread only by rhyzome growth, but now it appears that some hybrids produce fertile seed (see cattails look at the third paragraph under Great Lakes impacts).  I love cattails in the spring, they taste like cucumber, only better!

As you noted, it would provide dirt near the edge to create sound barriers (wonderful if your near traffic, or neighbors armed with boom boxes) and visual barriers (increased security, if thieves don't realize you've got stuff there, they never come knocking).  
It also discourages idle trespassing, allows you to define the paths people will take onto your property.
It will draw wildlife to the edge of your property.
Reroutes wildlife from coming deeper into your property.  (they could swim it, but especially in cold weather, it's easier to find another route).  
fishing, crawdading, maybe swimming, edible water plants.
total coolness factor!!!

Personally I would ditch the moat idea. Go with a low volume swaile to catch and distribute the grey water. On the up ditch side plant a thorny variety of blackberry or similar for production. The plants become your deterrent system, not the moat.

In Australia we pass water from kitchen sinks through a grease trap to catch grease, oils and solids.
They are small about 2 ft x 1.5 ft x 1.5 ft tall with 2 baffles.
They need regular cleaning otherwise they smell, but they are great to use prior to a reed bed, sand filter or pons system.
they refuse the biomass that draws oxygen from the water greatly.

I can't seem to find it now, but it seems I just recently saw a video of a guy giving a tour of his moat and all the plants he had growing out of it. It had nothing to do with greywater, but he installed it to keep his children and animals from running off too a nearby street or something. It went around the perimeter of his property, I think at least an acre or so.

In the meantime I have also been considering installing a moat around an animal enclosure, as we seem to have fairly high predator pressure.

I'm not sure how much of a deterrent it would be, but whatever makes it harder for the foxes and weasels to access our chickens has got to be of some value. Combined with fencing on both sides of the water, I think it would be quite effective.

Additionally, if the "island" were partitioned, it would also work as a victory garden/chinampa hybrid.

Thoughts?

Its possible to but an item called a Fox light, it flashes and is very effective at deterring foxes. Available in Australia, not sure if elsewhere. They are very good

The amount of grey water produced by a normal household would not fill a 'moat'. (Unless your moat is a miniature one...)

My experience in the matter:

All my grey water is separated from the septic system. The grey water (showers, bathroom & kitchen sinks, washing machine) is discharged into the open, goes through 1 ft wide x 1 ft deep 'swale' filled with crushed stone, which winds downhill about 10 metres and opens onto a relatively flat area where I planted a small circle of willow cuttings.

I've had this set-up for over a year now.  

Last summer, during the hottest and driest period, there was barely a trickle at the end of the swale (our household uses an average of 150 litres per day, and that includes toilet flushing, which is not grey water - and I presume most of the grey water that we released into the landscape during the summer percolated into the first few meters of the swale).  

From late autumn thru winter there's been quite a nice puddle at the end of the swale, due to reduced evaporation, the soil being already saturated from precipitation, and also due to additional surface water that the swale collects en route.

At any rate, regardless of the size of the 'puddle' accumulating at the end of the swale, and regardless of the season, the water in the puddle HAS NO SMELL.

In winter, the puddle is frozen most of the time.

John C Daley wrote:Its possible to but an item called a Fox light, it flashes and is very effective at deterring foxes. Available in Australia, not sure if elsewhere. They are very good

 In the States there is a blinking red light called Nite Guard. They work great to scare off the predators. They're solar powered so no wiring need. They cost about $20 each.

Okay then ...

to answer some questions raised -
1. we intend for this to not only have greywater but also combine with rainwater. I'm not sure of the volume of greywater we will have but there will be 4 adults living in the home and possible 2 more depending on circumstances. I had no delusions that the greywater alone would fill the moat. Reading that our greywater addition to the moat will be so small makes me feel like that this is a doable situation for not contaminating any native waterways and for providing moisture for plantings that I don't have to worry about weird stuff being absorbed through the soil.

2. Smell or no smell seems to be a moot point given that the percentage of greywater will be less than 10% of the whole volume of water and we are leaning towards a "pre-moat" area of gravel and reeds to help filter food debris, etc and oxygenate the water.

3. Length and width - Length is pretty set given the space we have. It is 120' from the house to the road, then turn the corner and it's 90' to the drive, 105' to the rainwater wash, and another 80' to the creek. Width and depth are variable at present. Thinking about 4-5 feet wide (difficult for most people to jump in a single bound especially with a steep berm on the other side) and perhaps 3 feet deep. But we've been considering adding fish to the mix after the first 120' run using a net or screen partition to keep them where we want them so we will have to look into what would be appropriate for the type of fish we want to keep.

4. Earthworks - honestly everything we do on our acreage is WORK in capital letters and frankly digging a moat around the edge where there are no trees or roots to contend with and where we can get an excavator in with ease seems much easier than digging a big round pond elsewhere and then contending with the dirt relocation. With the moat we can essentially scrape the dirt out and mound it on one side over a pile of branches and logs, cover with compost, and plant plants.

5. Dumping the water/water absorption ... We'd really like it to be pond-ish if possible, meaning that we would want water in it most of the year if not all year. We have a creek that was seasonal when we bought the place. within 10 days of a rain it was dry again. Fall and winter last year it didn't have enough to even be mud. Then we build a low-water dam... with a continual spill-way on it and it hasn't been dry since. We don't really understand how our two layers of concrete sacks less than a foot high actually created this phenomanom but somehow it did and we aren't arguing with the results. Anywho, the moat, we invision will have a gradual spill to it so that it doesn't flood, in theory, and will add a small trickle to the creek as well at times, maybe. It does get dry and hot here in summer and dry in winter.

6. The purpose of the moat - We had a two-fold purpose in mind. One is to increase the water on the property ... for instance we can build as many ponds as we like so this would just be a different form of a pond. And Two, lol, is not actually about the moat at all but rather the need for the dirt we would remove from the pond. The neighbor to our north is ... how to say this nicely ... an idiot who literally cleared his entire property of trees and filled in all his ponds and sprays his wheat with roundup before harvest and kills any living creature that dares walk across his land ... Naturally we want a barrier between us. On the east is a gravel road. In the summer the dust from the road settles in the grasses and trees and we don't get much infiltration into our property at all but in the winter, when the county mows down all the tall grass for fire prevention, the road dust is insane, Plus the noise from traffic at given times of the day is atrocious. So we wanted to build a berm and then put a fence on top of the berm to abate noise and dust and creepy neighbors. We can only build a 7' fence which isn't tall enough for our landscape but a 7' fence atop a berm would greatly increase our privacy and address our noise issues. I guess there's a 3rd purpose too, to deal with the greywater from the house. It's got to go somewhere.

7. Wildlife issues - I suppose a moat and berm system would work well for some predators but we're not that bothered by wild critters. We have tons of them and figure they were here first. Keeping them out of my chickens is my only goal. I plant extra garden because I know I will lose some. Our goats along with our LGD's are safe by themselves and we fence them up during birthing to protect the babes so that's not really an issue. Our biggest predator is the mountain lion and it would have to be a damn big moat to keep one out. We walk the perimeter every day and keep a look out for tracks. We mainly have raccoons and opossums and deer. We did have a bobcat but they take smaller things like rabbits and our LGD's are about 3x the size of a bobcat so no worries there. Owls and hawks and eagles and peregrins would only increase their population from a moat. Those that fish will have a supply and the water will attract other small critters that they prey on so perhaps a moat like we're discussing would keep them away from our chickens.

All in all this is looking more do-able and less crazy the more I think on it and read other's posts and thoughts on it.

Thanks for chiming in.

Hi, my experience of greywater is this:
We direct the greywater from our bathing block and our kitchen to two separate canals that go along trees. We are in a climate where trees require irrigation, so this just supplements it. And we are in a place where there's no regulation to stop us . Art Ludwig's wonderful and informative book Create an Oasis with Greywater says that topsoil is one of the best and simplest ways to treat greywater, in that the organisms get enough air to stay aerobic, reducing smell, and there are no pipes or filters to clog.

In our experience, with up to 100 people bathing, washing hair and clothes etc, and using who-knows-what-all soaps, detergents and "product," the willow trees love it.

In our experience with the kitchen cooking for up to about 40 or 50 people (vegetarian Indian food, no animal fat, and minimal butter) the kitchen's greywater canal smelled a bit up close, and the soil along the canal got very black, with white flecks of crushed eggshell.

Since we've had more like 100 people the past few years, that canal in summer smells pretty bad, and can be smelled pretty far away, so we are planning to add a tank to filter it using woodshavings. I am confident that if we make sure the outlet is at the very lowest point of the tank and never gets blocked, it shouldn't go anaerobic or smell bad.

In my experience, even the bathing water, which is not very dirty, smells bad if it is held for a few hours or overnight, but if it goes straight out to topsoil in the canal, it doesn't smell much.

I visited Anna Edey's composting flush toilet system on Martha's Vineyard, which convinces me that wood chips (or here in Ladakh we can only get wood shavings) would be the best filter, better than gravel or sand. See, with gravel or sand or baffles, someday you'll have to clean it, and dispose of that skanky greasy water used for cleaning it, or dispose of a heavy ton of wet skanky greasy sand or gravel. Whereas wood chips (and, I hope, wood shavings) will filter the chunks and grease and then compost them and let the nutrients dissolve and run out in to the rest of the system. You never have to remove the wood chips, you just add more when they shrink.

When I visited Anna Edey's house and saw her toilet system, she had buried a tank about 3x4x3 feet, and filled it with wood chips, and threw some compost worms in there. The toilet drains onto the top of one end of it, and the bottom drains out quickly from the other end so as not to drown or asphyxiate the worms. When she opened it there was a single turd visible on top with some paper, but no shitty smell. The rest was just black composting wood chips teeming with compost worms, and the whole thing just smelled like compost. She said it never gets full or blocked, she just adds more wood chips every once in a while. It was incredible.

So I'm planning to install an imitation of that here for our greywater before it goes out to the canals, and I expect the kitchen greywater won't smell so much. We can't get wood chips here, only shavings, so I hope that works. Also, Anna Edey's system drained down to underground perforated pipes irrigating pine trees, but here we mostly have trees with invasive roots like willows and poplars, so an underground perforated pipe wouldn't last a year, and anyway we're only dealing with greywater so it's fine to be on the surface (and we are unhindered by regulations).

I suspect that if you try to keep your greywater above ground as a pond or moat, it will stink. Bad.

You can do the moat idea, Bernie, but considering the volumes involved, wouldn't it essentially be a filter bed that drains into a moat pond system?

This sounds like a cool idea. It would be best if there was a current to keep it moving, or a waterfall to oxygenate, but build it like a pond system and it should do for you what you want it to.

-CK

The moat idea is wonderfull. In my area almost all farms had moats.
If not for security (keep out raiders), they had them for drainage controll, growing carp, geese and ducks, drinkwater for cattle and process water for the local flax industry.
Nature loves moats, so many good points there.

There is of course a butt.

Musquito's were a problem as well as the terrible smell.

So i would recommend a reed bed filter integrated in your moat system. A grease catch is needed to allow the bacteria in and on the reeds roots to clean your water. If no manure runoff or untreated processwater circulates back to your moat the reed bed system should be adequate. Reed beds are much in use here for sites that cannot drain to the local sewage plant. The reed beds are maintained in winter - the reed beds slow down in winter but don't stop working as long as the reeds roots don't freeze.
Whatever medium (reed/wood shavings/pumice/poreus brick/....) you use to grow your watercleansing bacteria on, it might be a good idea to inoculate your system with a little bit of water, plantroots and mud from a working system or a dich with a grey water influx. In my experience it helps a lot especially if low level motor oil concentrations may get into your moat.
 

The musquito's are a different problem. Near here (Flanders region, Belgium). Natural musquito controll relies on clear water and plenty predators (fisch etc...) hunting musquito larvae. I have no clou what might be good practice near you.



The moat is best designed with deep and shallows, steep and sloping banks, and with consideration to the light reaching the water. That way you maximaze your biodiversity. The reeds offer safe nesting and nesting material for birds. Carp is probably not a good species for you moat. If you run a creek trough you moat, you may have more options.

Have you considered what you may do with you waterplants and reeds ? We use reeds as nesting space for solitary bees, etc.....

I'm not sure if this applies in your area but, in Arizona, State Law requires that your greywater, as much as you can produce, without human waste, or kitchen grease, does not leave your property.  You could figure out many ways to make this happen, but it cannot go to your neighbors land, or leave your property as surface water... so you could irrigate, swales, ponds, etc., but the Dept. of Making You Sad would probably fill you in on your states requirements.

Hi Bernie, how did your moat plans go? Have you built it at this stage?

Lots of good comments already on this thread. I have a couple of brief points - the cleaner the water in your moat, the greater the uses for that water: Irrigation, fish, edible aquatics, swimming, etc. Thus if you can put a small grey water filter (wood chips then a small reed bed) first, then it will make it cleaner before it gets to the moat proper. Even if some of the moat is a designated grey water filter, that would do the same thing.

If you have grey water in the moat, does that make it a wastewater treatment system in your area? Here in Ireland a wastewater treatment system (including grey water reed beds and constructed wetlands) needs to be 3m from a site boundary; 10m from any dwelling; 4m from a public road; 10m from a stream; 15-60m from a well etc. It may not be an issue, but if it is, now is a good time to find out what your limits are.

Also - how do you plan on keeping water in the moat? Will the ground hold water for you with heavy clay, or is the groundwater high, or do you have a top-up source from a stream? Just consider that at the outset if you haven't already.

Happy digging,

Féidhlim