Extreme Cold Weather Greywater Systems

Cold Climate greywater has come up in various topics on this site. Most of the examples of greywater systems operating in cold climates are south of the more northern climates faced by Canadians or other northern countries.

Anyone out there operating or designing systems for extreme cold climate locations?

I assume that the amount of ice build up will be dependent on so many factors, that it would likely vary greatly from year to year even month to month?

What are best ways to create and utilize microclimates and how to use heat from greywater to enhance microclimates?

What are the best ways to deal with ice build up and containment of greywater melting in the spring?

What are the environmental concerns that need to be considered when there is ice build up of greywater? In a frozen condition, bacteria and viruses are non active, although those that can survive the freeze thaw may present a health risk during the melting?

My opinion is that where there is suitable land area to contain the accumulated ice and subsequent thaw, discharge to mulch basins would still be preferable to typical subsurface disposal below the frost line. There is such a difference in installation costs associated with a typical subsurface discharge system: time, materials, equipment etc. that I believe it is worth experimenting push the limits of conventional system installation.

I have been thinking about how, I would most simply design my theoretical system:

Maintain a 2% slope on all exterior plumbing and bury as deep as practical. Heavy mulch over the pipeline and add additional strawbales and/or piles of leaves for the cold weather periods over the pipe run to increase insulation.

I would design a mulch basin with a deep wood chip mulch of around 0.5 m. I would follow the recommendations on the Oasis site for mulch basin design and slope, although I would increase the drop from the outlet of the greywater pipe from 6" to 12" or as high as practical given the slope of your land at the discharge treatment area.

Cover the outlet with a section of infiltrator (U shaped septic pipe) or a plastic barrel cut in half with perforations, I wold cover this with strawbales and/or leaves to insulate.

I would assume that there is going to be layers of ice build of over time from the greywater that does not infiltrate. In the spring when things start to melt, I would cover the ice in leaves or straw to prevent contact with the melting greywater. This is only my assumption, so actually operating the system over a typical winter will let you know what is going to happen.

For kitchen greywater I would filter through a worm bin under the sink to prevent and food particles leaving the system, which may accumulate/freeze at the outlet. I would construct it from a rubbermaid sized container. I would probably only use this component during the cold weather periods.

Other greywaters would be connected directly to the final discharge piping.

When I do construct my system, I will start/experiment with the simplest system possible with a minimal amount of investment in time and money. For example, I am planning to experiment with a dishcarge pipe above grade and insulated with straw bales to test the system prior to any permanent installation, I can then monitor the system and I will maintain the option to divert to the sewer outlet should any issues occur. Should pipe burial and extra insulation be required, I will perform it and deepen and or expand the mulch basin at that time.

Thanks for posting this P. And thanks for posting on my own thread about the underground system.
I'm obviously curious about this. Hopefully someone will have some experience with this.

I really like the idea of the vermicomposting food particle filtration bin below the kitchen sink. This would be a desirable first step in the system, for sure.

The pipe could be covered with a hugulkultur, instead of straw bales or mulch.

HI P. Lots of ideas on what you wrote, and the resources you provided me to look at in my thread on Underground Greywater Systems.
A.) I'm definitely still in the brainstorm, ask for advice, and look for all possibilities stage, and you are helping me with all three, and I am very appreciative. I'm responding to some of the things you wrote in my 'underground greywater system' [from now on refered to as the UGWS thread! ] thread here, since some of the brainstorms (past and present) are not below ground.

B.) I value your experience creating greywater systems in Indonesia, and the amount of time that you have obviously spend thinking about a system in the North. I 'get' the banana circle as a great idea for uptaking/neutralizing/filtering the greywater nutrients and transpiring excess water. I'd love to have the system fully exposed to the external (outdoor) ecosystem and have direct flow of nutrients without a secondary process. But I'm not in Indonesia. And I'm not sure that it can be done fully outdoor and connected like that where I live (not in the winter anyway).

C.) I'm trying to figure out the best way to deal with the harshest that nature might throw at me on a bad winter in the Central Canadian Rockies. This winter is a mild winter, but we have already seen minus 20 C. A bad winter means: very cold temperatures (two years ago we hit -35 for over a week, and I've heard of -50 in the last 20 years), and no snow (although I live in the Interior Temperate Wet-belt against the western edge of the Rockies, and it tends to be snowy and/or wet most years... the old timers tell other stories of super dry winters for several years in a row), and lots of wind (which I can mitigate with good exposures, microclimates, etc, but are still a factor for any outdoor system), and very deep frosts (5 feet is not completely unheard of in a dry cold [no snow] windy year, from what the old-timers say-Yikes! Hopefully climate change is working in my favor here). And so I'm super grateful for you starting this thread.

I'm going to quote from one of your last comments in the UGWS thread.

1. The best treatment of greywater occurs in the upper region of the topsoil
2. A well built and maintained mulch basin will not fail even if the system is abused (ie. grease and solids handling capabilities)

D.) In regards to this quote, the following comes to mind:
I was thinking at one point of having the bins be in separate solariums; one down-slope of the other. Another option on my sloped property would be having the solarium itself be stepped downhill with both bins in one solarium (more likely). Either way, the bins would basically be sitting so that their top rims were at floor grade, and exposed. The bins would be planted densely with comfrey and maybe mint and other perennial heavy feeding moisture lovers, which could be chopped and utilized for mulch/compost building elsewhere. These plants might experience a die back at the extreme part of the winter, even in a solarium, unless I supply heat... although the semi active passive heat release system I describe in the UGWS thread might work to keep the comfrey/mint all season. Indoor solarium Hugulkultur could be used to insulate the pipe between beds, or outside between solariums.

*Idea's on other plants for this would be appreciated* ~Zone 3 or 4 (maybe zone 5 or 6 if it's in the solarium).

E.) Still working with your quote above, and also mentioned in my response above from yesterday, I like the idea of the under the sink direct drop grease trap worm bin that you mention in this thread. It has been in and among my thoughts to utilize this sort of idea in some form or another. I was contemplating having one of the large plastic caged fluid containers that we discussed in the UGWS thread, in the kitchen itself as the initial stage in the system (an possibly kitchen compost waste bin). The house is not built yet, so almost any permaculture possibility could be incorporated if not too costly. So, this could take in the initial drop of dish water onto deep mulch/worm pit, and even have some plants (comfrey, mint... ) off to the side.

F.) I created a thread asking if anybody had experience with the Earthship Greywater Systems (which is similar to the above mentioned worm bins but larger in volume (more like a homemade indoor swimming pool that is transformed into a swamp/damp soil system with a diversity of moisture loving plants) , which I read about in Earthship III , I believe. The only response in that thread indicated that it works in the dry climate that it was designed in, but might not be great in a place where the excess moisture/humidity might not be appreciated. So instead of containing the whole system indoors, I contemplate going into a separate solarium building to further process the nutrients and liquids, as described above in D. I'm not complete against this concept of fully incorporating the system in the house, if someone can verify that the Earthship system might work in my climate, but I doubt that I could process all that water without transpiration and resulting humidity problems.

I've been reading this post on my phone but only got a real internet connection today so I'll quickly upload a photo of our winter greywater. Not impressive, not by a long shot up to any kind of "code" but very very foolproof...

As you can see from the skating rink, it is a cold climate. Nights in January are -21C most often, and occasionally -25C. It's a very dry climate, we've got plenty of space, and there are no regulations.

See the field with two blotchy patches of ice? Those are two greywater outlets. The one lower in the picture is from the kitchen , and the one just above it in the picture, in the same field, is from the bathing block (no toilets). The larger amount of ice tucked in under the trees is not greywater, it's ice-rink watering overflow, where we release the pipe when the rink has had enough.

In summer those greywater pipes outlet into the canal that goes along left and bottom (in picture) edges of that field, which has apple and apricot trees all along it, and a few willows. The willows just love all water, including the yickiest greywater you can throw at them. 15 years ago, our first biggest apricot tree was next to the bathing block outlet, and it burst into glorious bloom one spring and then never proceeded to leaf out. I assumed that something wrong had been dumped down the bathroom sinks, but I never did find out what happened. The later apricot trees haven't been bothered so far, and have been producing for over five years. They do get clean water as well as greywater, so the earlier greywater might have been too dense with stuff.

In summer we keep the greywater contained in the canals and occasionally flushed with fresh water, and try not to water the veggie garden with greywater. In winter, to reduce the ice buildup in the swale along the cliff edge, we usually let the greywater just spill out into the garden and soak in and/or sublimate. The garden soil seems to like it just fine. I don't know, we haven't had a problem with it yet except maybe the tree mentioned above.

The surface greywater in the canal in summer sometimes smells. The bathing block water smells a bit stale-soapy when you're right next to it, but sometimes the rich kitchen sink water stinks atrociously and we have to go out and dig fresh canals or dig out the rich black muck, or whatever. But usually it's not that bad.

Thanks Rebecca, your post and photo is a great example of a larger installation operating successfully for many years. I have read a couple of your posts on similar cold weather related topics and your information is what led me to consider designing my system to allow for accumulated ice build up and control of spring melt.

Are you using greywater to create the skating rink or is it coming from the nearby surface water?

There are multiple families living in your community, can you remind me of the numbers?

How deep are your pipes buried, do you do anything additionally to insulate pipes for cold weather periods?

During your winters do you typically get day time temperatures above zero where some melting of the accumualed ice will melt?

How does the photo you included compared to typical and maximum ice build up during cold weather periods?

In winter, to reduce the ice buildup in the swale along the cliff edge, we usually let the greywater just spill out into the garden and soak in and/or sublimate. The garden soil seems to like it just fine.

At some point were there ice build up issues, or was this part of the design to mitigate a potential problem? If you did have ice build up issues, could you provide some information as this would clearly be situations to avoid?

Have you notice or observed any microclimates being developed at the greywater discharge locations. ie. less frost depth in the surrounding soil area during the winter or frost pockets being developed that take a longer time to melt compared to surrounding areas?

In my yard I created a rainwater garden on the north side of our home, due to spring freeze/thaw conditions and the location of the garden, it is usually 2 weeks behind the rest of my yard in melting to exposed ground.

Thanks again, I'm sure that your information is appreciated by many considering greywater systems in colder climates.

Roberto, I would definitely recommend that you purchase any of Art's books that correspond to your areas of interest. They are affordable and packed with practical useful information.

On my spectrum of cold weather greywater systems, my theoretical design is the most basic system I can think to practically construct and I want to explore the potential of determining how far you can push these minimal design criteria and what elements need to be considered in order to best protect the environment and prevent system failure.

On the other end of my spectrum would be the "Solar Greywater Greenhouse" as per Art's book. Chapter 8 details more advanced greywater systems and he provides examples of Solar greywater greenhouses's in operation and provides some general design considerations. If I had unlimited resources and knew that I would be living in my current home longterm, this is definitely the system I would design as part of my house. It would provide year round potential use of the greywater resource and assist in regulating household temperature and humidity. The greenhouse would also provide the ideal location for experimentation of different greywater treatment and reuse concepts year round. It is also a great investment for your home and quality of life, a definite added bonus. I am not sure if this would help in resale value, as not all would appreciate such a system.

I am not including advanced engineering solutions as part of my spectrum of greywater systems: These include mechanical filters, storage tanks and pumps that are being marketed as greywater treatment systems. I think that these systems can be avoided in most applications. Again Art's book and website do a great job of evaluating and discussing.

Thanks P.

I'll definitely consider gettting a book from Art.

Thanks for your continuing insight and recommendations.

Much appreciated.