Tag Archives: water

Water Harvesting

It’s time to talk about water harvesting. Most conventional housing either has their water coming from a well or the water grid of the municipality in which it is located. Earthships don’t use either of these methods and we are going to discuss the how and the why of that here.

Earthships make use of cisterns at the back of the building to store the water that is used inside. You can see a cross section of one of the cisterns in this drawing.

Here is a top view showing five cisterns in the plans for this Earthship.

Why cisterns? Well there are several motivating factors at play here.

First of all, Earthships were designed to be built just about anywhere on the planet. With this in mind, an Earthship must be self-sufficient and independent. An Earthship takes care of itself and if you hook it up to a municipal water source you are then dependent on it for your water. If something happens to that water source, you are affected, just like everyone else connected to it, and you can’t do anything about it. Stories of communities that have had boiling requirements (huge energy usage there) for their water, or those close to fracking operations who can light their water on fire as it comes out of the pipes are a few issues that come to mind.

Water contamination is one thing, but you are also subject to how your municipality treats their water as well. Overuse of chlorine and fluoride can make city water disgusting, unpalatable and unhealthy, forcing many to buy bottled water which defeats the entire purpose of having municipal water in the first place. Why spend all that money on plumbing your house if you can’t drink the water?

What about being connected to a well? In some parts of the world, like where we live, this is very common and for the most part sustainable as we do get quite a bit of rain over the course of the year. However, there are still weaknesses in this setup. If you go through a dry spell where you don’t have any rain for a while, you have no idea how much water you have access to. Water underground generally moves and you can never be certain of how much water you have flowing into the bottom of your well or out of it. You’re also subject to all of the issues that comes with underground water: hard water, sulfur water or contaminated water caused by run-off from industrial farms or other pollution sources. Sometimes you have to go to extreme depths to get to a water source, meaning you’re going to spend more energy bringing it out of the ground.

In some parts of the world, so many wells have been dug in an area that all of the ground water has been drained and it won’t be coming back as those were ancient aquifers and don’t have any new water coming in. I also saw an interesting documentary on sink holes a while back. Water underground takes up a certain amount of space. If you drain that water, you create a large cavity under ground and sometimes the ground above just falls into it as there is nothing to keep holding it up. There was one incident in the state of Florida where two days of frost forced the citrus growers to continuously spray their crops with water for 48 hours. That pulled a lot of water out of the aquifers and in the week afterwards, they had 60 (yes six-zero) sink holes, some of which swallowed houses and their occupants.

I’d also like to point out a literary metaphor for drilling wells. Mosquitoes are well known in our part of the world, especially in May and June. They land on you, stick their proboscis in your skin and suck out your blood. We are doing the same thing with wells to the earth. We stick our long pipes in the ground and suck out the blood of mother earth. Do we really need to be poking so many holes in the earth?

Earthships, on the other hand, catch their water from the sky. This is why Earthships always have a roof that is designed to catch water. Global model Earthships use a metal roof. Other designs use concrete or plaster. Whatever you finish your roof with, make sure it doesn’t have any toxic elements in it that will contaminate your water. Incidentally, rain water is always soft.

I should mention here that you can still get polluted water from the sky, depending on where you are located. If you are downwind from a major polluter (e.g. east of Beijing, for instance), the rain water you get may have serious contaminants in it. My advice: don’t build there.

The first question I usually hear when I talk about this is: will you have enough? Having enough water is based on several variables: how much precipitation you get in a year, how much of it you can store, how big is the surface area of the roof of your Earthship and what are your usage metrics like. If you like to take four or five showers a day, even on a well you won’t have enough water. If you can sit down and calculate how much water you use in a week, multiply that by 52 so you can get your yearly usage, then you have some idea of how much water you need to be storing. If they can make it work in Taos, New Mexico where they only get 8-12″ (20-30cm) of precipitation a year, then you should be able to make it work in all but the driest places on earth. You just need to make sure that when it does rain, you catch as much of it as you can.

The other advantage of storing your water in cisterns is you can always go look and see just how much water you have. Additionally, if we ever got to a point where we weren’t getting any rain and the cisterns where hitting critical low, we could hire a water truck to go visit a lake or river and refill them. We do live in an area with a huge abundance of lakes and rivers. You couldn’t refill your well that way, though.

So, you catch a whole lot of water in your cisterns and now you want to use it in your house. How does that work?

All of the cisterns are joined together so the water you have will distribute itself evenly across all cisterns. One input line goes from the cisterns into the house, where upon it is connected to one of these.

This, in Earthship jargon, is called a WOM. A water organization module. This is the thing you need to take the water from your cisterns and turn it into usable water in your house. I have put numbered labels on the picture and I will give a description of each of them.

  1. Input. This is where the incoming line from the cisterns is connected, with an appropriate cutoff valve so you can turn off the water for WOM maintenance.
  2. 50 mesh (300μ) filter, used to protect the pump (see 3).
  3. DC water pump.
  4. Pressure switch.
  5. 500 mesh (28μ) filter.
  6. T-joint. The water that goes down from here branches into your hot and cold water that will be used for washing and bathing.
  7. 1000 mesh (15μ) filter.
  8. Ceramic drinking water filter (0.5μ or less)
  9. Drinking water output line

If you followed that, you saw that there are separate lines for drinking water and generic washing water. You don’t need to filter washing water as much as you do drinking water, thus the separation. All of the filters that are traditionally used in a WOM have filters that can be removed and cleaned without the need to replace them too often. Of course, if you build your own, you can use whatever components you like.

I should point out that if you are building one of these in Canada, you can’t use PVC connectors like what is shown in the picture. PVC, by code, can only be used for drain pipes, not incoming lines, due to the toxic nature of PVC plastic.

There is also a small modification to the WOM that will make your life a lot easier if you want to know how much water you have in your cisterns.

Just before the valve on the incoming line (number 1 in the WOM photo) you put another T-joint and attach a clear plastic pipe running straight up.

You want the top of this pipe to be higher than the tops of your cisterns. As your cisterns fill up, so will this clear pipe. In fact, the level of the water in the clear pipe will always show the level of the water in the cisterns, just due to the natural leveling action of water. A very simple solution to monitor how much water you have and it doesn’t involve taking the lid off your cisterns and sticking your head in it to see where the water level is at.

Obviously there are a few other components to a standard plumbing setup in a home. You’re going to have a pressure tank to make sure all of your water fixtures get water at a decent flow rate. That being said, if the pressure tank or pump ever fails, the way the cisterns are positioned to the rest of the plumbing, you will still get water just by gravity. It won’t flow as fast, but slow water is better than no water.

Additionally, you’re going to probably want some hot water. This is usually accomplished using a solar hot water heater and a gas on-demand system as a backup. The solar hot water heater is another panel that heats water from the sun instead of generating electricity. It will have a large coil of metal pipe running through it. Actually, the panel doesn’t heat the water directly. You use glycol instead because it has a much higher boiling point than water. You heat up the glycol by running it through the panel then run the pipe down to a heat exchange tank where it transfers the heat from the glycol to the water. While the sun is out, this can give you some very hot water. If you need hot water after sundown, this is where the backup system would be used. If you can adjust yourself to use the majority of your hot water during the daytime, you won’t need to use your backup system hardly at all.

Now that you have your water filtered, pressurized and heated, you can put in the rest of your plumbing to get the appropriate type of water to the appropriate fixture. This is the same standard type of plumbing that you would have in any house.

There is more to the story of water in an Earthship, but that will be covered in the section on Contained Sewage Treatment.


Contained Sewage Treatment

Continuing the story from Water Harvesting, now we’re going to talk about what happens to all of that water after you’ve used it. In the case of a conventional house, after you use some water, it just goes down the drain and leaves your house forever. This is not the case with an Earthship.

When you take a shower, wash your clothes or do the dishes all of that waste water (called grey water) is routed for use by the plants in the green house.

In the above image, you can see the main wet wall in magenta (labeled in red). You should also take notice of where that wet wall is in relation to all of the water related features. The WOM is just to the north where the water line enters the building, along with the laundry facilities. The one bathroom is on the west side of the wet wall and the kitchen is on the east side. This makes sure all of your plumbing is simple and centrally located. This is a small, single bedroom Earthship so having only the one wet wall makes things simple.

Following the yellow line, this is the grey water drain from the main wet wall to the start of the planters in the green house on the east side. Here, the water begins its journey through a series of planter cells as shown the next picture.

How many cells you have in your Earthship depends on the size of the green house and your own personal preferences, but the whole point of having these cells is so you can grow plants. If you are going to grow plants, you might as well grow things you can eat. So every Earthship has a element of generating food for its occupants.

Going back to the grey water, it empties into the first cell, feeding the plants there. Each cell is slightly lower than the previous cell so the water naturally drains from east to west into the last cell, which is the lowest and the deepest.

This last cell has a small well where any water that makes it through all of the planters will gather. It is the water in this well that is pumped to the toilet for flushing. The water that leaves your toilet after you flush it is called black water and this is the water that actually leaves the house. By this point the water has been used several times: first use was when you took a shower, second use was to feed your plants, third use was to flush the toilet. This drastically decreases the amount of water used compared to your average home.

The black water leaving the Earthship then enters a typical septic tank where the solids and liquids are separated and the liquid effluent exits the septic tank. Normally, the effluent then drains into a leach field but with an Earthship, there is another botanical cell before the leach field so you can grow even more food and have a fourth use of that same water.

Now lets look at a few details that I’m sure you’re wondering about.

First off, if you have an exterior botanical cell to process the effluent coming out of your septic tank, won’t it become inactive during the winter? Yes, indeed, it will. If you’re in an area where we are, our winter can be pretty lengthy as well, reducing the amount of time that cell will be viable to maybe five months. So, it might be something to consider leaving out for that reason as it will save you time and money.

Additionally, there are issues growing food that is fed by septic tank effluent. You don’t want to grow any thing like potatoes, carrots, beets or any other root vegetables, along with things like celery, lettuce or kale. Anything where the part that you eat comes directly from the soil is a no-no as it can be contaminated with nasties.

On the other hand, anything that grows from a stock, vine or tree is fine. Things like squash or pumpkins, tomatoes, peppers, berries or apples are all fine as those things are all picked off a plant, as opposed to eating the plant or its roots.

Inside the Earthship, you have a lot of freedom to grow almost whatever you like as the interior green house will continue to work year round. The two most popular plants inside an Earthship are bananas and figs. Imagine living here in Ontario and growing your own bananas. We’re definitely looking forward to that.

Food production is one of the six essential things that make up an Earthship and it will be covered in its own post.

Earthship Island, Day 21

Two days ago we came upon this guy. He was much larger than most of the other hermit crabs we have come across.

He looked quite oversized for his shell so we tried offering him a bigger one.

Unfortunately, he wasn’t going for it. I don’t think he liked being handled so much and just wanted to get away. We left him be, but he still didn’t take either of the shell options we offered.

The mornings here are usually pretty nice. The wind is calm and the tide is out. Sometimes the sun shows up too.

Yesterday afternoon the clouds rolled in and we were pretty sure it was going to rain on us. Here is what it looked like looking out from the Earthship.

It wasn’t long after I took those photos that the sky opened up and the rain came down.

It was fascinating to watch as the rain smooths out all of the waves coming to shore.

This rain was driven by strong winds from the south, so the back of the Earthship fills with water.

I had put a towel over the door to try to reduce the wind and rain coming in. It did cut down on the wind, but didn’t do much for stopping the rain.

Out front, we saw this guy out in his boat in the rain storm.

He didn’t seem overly concerned. He did pull into shore in front of the Earthship to bail out his boat and the headed back out, sticking to the shoreline.

I was watching all of this and thought to myself, “how many opportunities will you have in your life to go out and experience a tropical rain storm?” So I ran out into the rain and had a good frolicking.

I have to say that compared to the rain water, the ocean water felt like bathtub warm. I yelled out to Kat, who took the picture, “This is the coldest I’ve been since we arrived!” The rain was chilly, but not unbearable.

I can mark that down on my list of exciting life experiences.

Earthship Island, Day 19

Yes, we’re getting close to the end of our Indonesian portion of the trip. Katrina is heading out on the 27th and we are leaving the island on the 29th. We decided to leave a day early and spend an evening at a place near the mountains before our flight. Katrina stayed there before joining us at the island so we have a good idea of what to expect.

I must say that after eating nothing but rice, fish, and cooked vegetables since we arrived I am quite ready for something else. Actually, some ice cream would be really awesome, but that’s not going to happen while on Kenawa.

Sometimes the ocean water is really calm. Here is a picture if you don’t believe me.

I mentionedin a previous post about skipping rocks on the ocean and I wasn’t kidding. The weather here is very north/southish instead of the normal east/westish. As a result one side of the island is usually calmer than the other side.

When the wind picks up, it starts to look like this.

It gets pretty wavy, especially over the dead coral section we walked on a few posts back. Waves break when the height of the wave is half the depth of the water, so it hits the shallow part, breaks, and then has to work itself up again before reaching shore.

Right along the beach there a lot of these vines with pink flowers.

The flowers all close up at night, or if it gets dark from a storm. There aren’t many types of flowers on the island, but these are the most common ones.

On yet another jaunt around the island we came across this little guy. I say little, but his shell was probably the size of a lemon.

This is actually a konch and not a hermit crab that has taken over an empty shell.

With the wind giving us a stiff breeze, walking around the north west tip of the island where it gets rocky, you can get some good splash action.

Nothing like watching the waves splash up on the rocks, bathing all of the crabs.

We’re counting down the days and we don’t even have a drill yet. As far as further building projects go, that may fall to the next group taking over after us.