Come On Out, The Water’s Fine: Rob Talks Rain Tanks!

 In Built Environment, Design, Energy Systems, Featured, Food, Greenhouse, Permaculture Projects, Plants & Living Systems, Rainwater Harvesting, Retrofit, Water

Here is a short video on setting up a low-tech rainwater harvesting system that can be employed for an urban yard. The tank we chose is typically used for shipping food all over the world. While the volume of these tanks is relatively small, they work for small irrigation projects like our salad greens bed.

In this video, Rob walks through his and Michelle’s urban home-scale system and explains the function of each component, from the flapper valve (allowing us to drain the tank for winter), to the rain head and first flush diverter (keeping organic matter out of the system), ending with the weeping tile that directs overflow to our garden swale. 

Can you harvest rainwater from asphalt shingles? What factors do you need to consider when selecting a storage tank? We’ll look at all of this and more.

In addition to the video, we’ve included a drawing that details all of the components of a rainwater harvesting system. 







Here’s an infographic that pulls all of these ideas onto one page. Please click to download and share!

Interested in learning more? Check out our course offerings, Essential Rainwater Harvesting book, plus loads of free resources HERE.

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Showing 19 comments
  • Charlie

    I don’t know. I dont have money for harvesting water. Any tips?

    • Rob Avis

      There are low cost easy ways to do this. Its the most important thing to do.


    Is it necessary to lab test rain water that you collect off your roof. I live just south of Calgary and had new asphalt shingles put on in fall of 2013.

    • Rob Avis

      Its not a bad idea, especially if you have a tar shingle roof. I would not be too worried if you have a steel roof.

  • Jose

    Hi Rob

    Could you tell me where I can purchase a first flush diverted from here in calgary


    • Rob Avis

      Regency Irrigation

  • Nolan

    Thanks for the video and the comment responses above. They mostly answered my questions. Does it present any issues to stack totes?

  • Anne

    Thanks for the video. What kind of pump do you use for watering your garden bed from the rainwater tank? Does it go on automatically or manually? Is it 12 volt or 120.? Where did you purchase it?
    We have a 800 gallon tank that collects rainwater from the barn. I gravity feed the water to my cattle and sheep. I have no first flush diverter, but I think its a good idea. the animals prefer this rainwater to the well water we ourselves drink( they get it in the winter as we drain our water tank.)

    • Rob Avis

      I use a surflow diaphram pump which is inexpensive and fairly robust. I use it manually but it should be on a timer. Because it is a positive displacement pump (as opposed to a centrifigal) it should act as a valve when it is off and a pump when it is on. This means that you should be able to keep the tank open to the pump and just put it on a timer. However, timers can’t evaluate how moist your soil is so you could end up over watering with a timer. If you are watering your cattle with rainwater you should harden the water with limestone or oyster shells to precipitate any heavy metals.
      Thanks for the comment.

  • Joanne

    Great video Rob. One question – you say that you can harvest water in a potable fashion off an asphalt roof. Can you say more about that and what you base that on? I have come across conflicting opinions on this on the web from yes it’s potable, you can use if for watering fruit trees and vegetables or anything you want – to – only use water from an asphalt roof for flower gardens and non-fruit trees – to well it’s okay if you use a first flush system. Gets a little hard to sift through everything. I am using water of an old asphalt garage roof. It runs through a series of swales and spillways in a small forest garden and key-hole vegetable beds. The plants are thriving. I’d appreciate you thoughts on all this.

  • Ray

    Wish I’d seen this great little video before I installed my tank. Very useful ideas which I’ll be incorporating should I ever install another tank.

  • Sam

    Great video and description of a water catchment system.
    A few questions:
    1. Do you think painting the outside of the tank would work to stop algae growth? I know cladding would likely look nicer and fit into the surroundings better (aesthetically) but is paint sufficient enough to stop the growth?

    2. Could you source the manufacturer and/or supplier of the diverter, filter and floating ball/drain that you used in the system?

    3. How did you prepare the area where the tank is sitting? A full tank of water weighs quite a bit so I would think just clearing the area and tamping down the dirt would be insufficient to provide a good base for the tank to sit on.

    4. Can you tell me what the difference is between a “food grade” tank and non-food grade? There is a local resource that is selling the tanks but doesn’t think they are food grade and I am trying to determine if they would be ok to use in an irrigation system.

    Hope this isn’t to many questions and keep up the good work.


    • Rob Avis

      1) Yes painting would work. Make sure it is opaque.
      2)Wayne Building Products and Regency irrigation.
      3) I dug down to subsoil and then replaced the top soil with self compacting fill.
      4)The tanks are used for all sorts of liquid transport including petrochemicals. If you use these tanks I recomend using ones that have been used to transport food.

  • goatboy825

    Sweet video and graphic.

    Stumbled on your site through Geoff Lawton PRI (he’s following you). I am taking his on-line PDC so I can learn more about design and work with people here in Boise.

    Has the consultancy business been self-sufficient?

    I currently work from home as an architect with a civil engineering firm. Would like to share permaculture with others and am curious how well the consultancy business has been for you.

    As a side note, Mark and Amy Cummins from BC introduced me to permaculture when the relocated to Boise. The movement is very strong in Canada.

    • Rob Avis

      Yes work has been self sufficient. We are full time consultancy and education.
      Thanks for the comment.


      PS I trained with Geoff.

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