Building An Earthship In Darfield, B.C.

We are a family of five living in Darfield, BC.
Our house is six hundred square feet in total and we are feeling cramped.

We have decided to build an earthship!

So starts the adventure ...

Thursday, January 22, 2009

Investigating Graywater


I’ve spent the last couple of days trying to wrap my head around the implementation of a gray water recovery system for the earthship. The information provided in the Earthship volumes by Mike Reynolds is not detailed, and as gray water recovery is not a common building practice it is difficult to find information on this topic.

First a bit of background … Fresh water (from a well or rainwater cache) is degraded after it is used residentially; it becomes either black or gray water. Black water refers to the outflow from toilets, which contains fecal matter and is difficult to treat. Gray water is the outflow from the remaining plumbing fixtures in the house; sinks, showers, baths and laundry. This water is easier to treat and it is this water that we will be recovering in our gray water recovery system.

From my initial research the regulatory work done on gray water systems in Canada is only at beginning stages, and deals mostly with the recovery of gray water for later use in flushing toilets. This model of gray water recovery stresses the chlorination/treatment of the gray water so that it can be stored for later use. This is an expensive process requiring chemicals, storage and pumping that is not what we are interested in. Our intention is to contain, filter and then use the gray water in a constructed wetland environment located in our residence. The gray water will be purified in this environment and used to grow plants and fruit trees. This basic approach is described in Earthship Volume 3, but as I said earlier, the implementation details are vague.

In Canada the CHMC (Canadian Housing and Mortgage Corporation) is doing some research into gray water systems, and seems to be involved in defining standards. Cate Soroczan is listed as the Project Manager on much of this work and would seem to be a useful contact. I intend to start with the CHMC to determine what regulations govern the implementation of a gray water system in our jurisdiction and what standards exist.

My other approach to investigating gray water was to try and determine generally accepted construction methods and practices with regard to gray water recovery. As gray water recovery is not used in mainstream North American construction there seem to be a lot of conflicting opinions and practices in this field. The work of Art Ludwig is referenced often on the internet by various organizations (The Real Goods for one) and people, and as it turns out he has two books out on the subject; ‘Create an Oasis with Gray Water’ and the ‘Builder’s Gray water Guide’. I have decided to pin my hopes on Art Ludwig’s experience and have ordered these two books (www.oasisdesign.net). Hopefully, when these two books arrive I can start laying out a gray water recovery system in earnest.

In the meantime I think I have tracked down enough information to flesh out the square footage and basic layout required of a gray water system for my family of five. This should allow me to carry on with drawing my plans and ensuring that I have allocated enough space for gray water recovery and located the system logically in our home. The initial information on gray water that I will be using in my design is 35 gallons per day / per person of gray water generated residentially, and from .14 – 1.2 sqft of gray water ‘mulch field’ per gallon of gray water generated per day.

In other words, my family of five will generate 175 gallons of gray water per day, and the gray water field will need to be 24.5 sqft on the low side to 210 sqft on the high side. For the time being I am going to stick to the upper end of this estimate and design a gray water field of approximately 200 sqft. With this information in mind I have modified my plans as detailed in the attached drawing. I will modify them again as I learn more about gray water.

Most of the changes in this iteration of the plans are based on layout and our ultimate preferences. We re-arranged the kitchen and pantry for better work flow. Sandra wanted easy access to the outside from the kitchen so we added a vestibule and door in the middle. We have added a second toilet so that we are not all lined up to use the bathroom. I cannot easily figure out how to move the second bathroom closer to the master bedroom given the constraints imposed by the water system. Sandra and I have agreed we can live with this layout.

12 comments:

burkhold said...

It occurs to me that the area that shows two kids' bedrooms there, could probably have 3 (smaller) kids bedrooms.

Just sayin'.

Jennifer said...

I am with burkhold. Five people and three bedrooms!

Love the series so far. Does the use of the gray water for watering plants and fruit trees mean that you are reconsidering the tilapia?

Chris said...

As far as the question regarding whether we are reconsidering the tilapia ...

The short answer to that question is no!

The longer answer involves an explanation. The gray water system will (as of right now) use the majority of the available planter space. This leaves some of the planters free, notably the ones right around the cistern.

The intention is that the cistern would hold the tilapia, and the planters around it would be used for an aquaponic nitrogen cycle. In other words, the cistern would be used for maintaining an aquapoic system and overflow could be diverted to outside planters.

The idea is to keep the gray water and cistern 'water sheds' seperate. The reason for this is simply that the gray water must be treated in a contained planter. At least, that is my current understanding of regulations that may impact gray water. I am still investigating. Hopefully over the next couple of weeks my plans will start to detail the water systems!

As far as three bedrooms ... I imagine we will be having lots of family discussions on this issue. My only structural constraint is making sure the bedrooms all have a fire egress, which is easier to do with two bedrooms than three!

Chris

Pete said...

I just got a copy of Michael Reynold's book "Water from the sky" from Amazon. It's basically a detailed description of the whole Earthship water system, from collecting it from the roof, storing it in cisterns, graywater, blackwaer, and so on.
I think it would probably answer a lot of your questions.
Also - if you need help regarding code issues, there is an Okanagan ex-building inspector who's set up his own sustainable building practice. See: http://www.flywheelbuildingsolutions.com/. He's a fair way away from you, but he might be able to give you some help at least over the phone.

Pete said...

Also I think you can ask for email or telephone consultancy help direct from Earthship Biotecture in New Mexico. I think they charge for this.

Chris said...

Pete,

Thanks for the information about "Water From the Sky".

I have most of his other books but did not get that one. Perhaps I will order it ...

As far as consultation we might swing a trip to Taos later this spring so that we can see many different buildings for ideas. One of our goals in implementing this project is cost-effectiveness and so far we have opted not to pay for any consultations. This may change as our project progresses.

The Potter Earthship in Ontario also has a website with some good information on how they layed out their gray water system.

Also, I just finished reading 'Create an Oasis with Greywater' and would strongly recommend this book as a reference.

Chris

Pete said...

Hi Chris,

I had a look through 'Water from the Sky', and it says that for graywater the gernal rule of thumb is to allow for 25 square feet of planter space per plumbing fixture. I don't know if that helps?

Cheers,

Pete

Chris said...

Peter,

I have 4 plumbing fixtures (2 bathroom sinks, 1 kitchen sink, a tub). This would imply 100 sqft of gray water planter space.

I have difficulty with this number because a house for a family of five (our situation) would generate the same answer as a house for a family of two. What allowance is made for the number of people living in the house?

I came up with a figure of about 200 sqft after looking at 'Create an Oasis with Greywater'. I hope this number gives me a realistic upper size limit on my gray water planters, and I am also happy that two different books give results that are in the same ballpark (100-200 sqft).

I am curious ...does 'Water From the Sky' give more detail on the gray water planter construction than is provided in the three Earthship Volumes. I have found the information in these books a little sketchy. I am thinking of buying 'Water From the Sky' as it is not available in our library system, but am wondering if it adds to the Earthship Volumes in this regard.

Chris

Chris said...

OOPS ...

Pete,

In my last post I had actually meant to ask you a question.

Does the book you are currently reading give more detail than the three Earthship Volumes on graywater planter design?

I've spent the last 10 minutes trying to edit my last comment (unsuccessfully), and have given up and added this post seperately ...

Chris

Pete said...

Hi Chris,

Sorry - I've been really busy so haven't been able to reply.

I meant to send up my copy of Water From the Sky with Alice Hooper (www.thispreciousplanet...) when she went up to see you, but didn't have the time.

Does it give more detail? I can't really answer that question because I've only got Earthship Vol 1, and I haven't read all of that one.

Do you want me to post you my copy of the book? You can send it back to me when you've finished, or I can pick it up when I (eventually/hopefully) manage to get up there and do some volunteering on the construction - if you're looking for volunteers.

Pete

Pete said...

Actually, I'm going to be at a sustainability conference at Chu Chua Community Centre, Barriere, on March the 10th.
You could always come by and pick it up from me then. Save on the postage.
I can only be around for a few hours then, having to come up from Kelowna in the morning, and then take the Greyhound down to Vancouver in afternoon.

Pete

Chris said...

Pete,

If it works for you I would love to borrow that book from you when you are in the area. I have ordered the book but the delivery date is in late March and I was hoping to check my work against it. I could mail it back to you when I am done if that works. (You are definitely more than welcome to visit when we are working on the building).

Give me an idea of what time you will be at the Chu Chua community centre and I will meet you there.

Chris

P.S. - you can email me directly at chris@northriverloghomes.com.