Rainwater collection for a rental property

Discussion in 'Members' Systems' started by Pragmatist, May 26, 2013.

  1. Pragmatist

    Pragmatist Junior Member

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    Some of you would have seen my thread asking for advice on this topic but now that it's actually starting to take shape, I thought I'd document the progress and lessons (being) learned here under "Members' Systems"

    The basic situation is that we finally got the owners to remove the broken tank out the back of the shed, leaving us with a reasonably clean slate to install our own system. The space available was 6m x 2m with the maximum height of around 2.5-3m. Our worm farms are in the space and we lack much alternative suitable space for them. Guttering was in place and mostly intact (slight leaks in places due to rust) although full of muck. One side of the guttering was connected to some 50mm pipes that previously fed the old tank. The other side was left to drop to the ground from a hole in one end.

    Our requirements were:

    • low-cost
    • portable
    • flexible enough to fit into wherever we move next
    • store about 5-10KL of water from winter to water the ~60sqm garden through summer without worrying about water restrictions. This capacity is based on catchment area and historical median rainfall figures. We have no idea how much water the garden would need as it's new and still evolving in design.
    • Preferably not require mains power as there is none out the back of the shed.
    • low-maintenance and unattended operation as much as possible
    With that in mind, I decided on an IBC-based system connected with regular black garden poly pipe with a solar-powered pump to transfer water between tanks.

    Here's a photo of the space with the first two tanks in place. The black containers are the existing worm farms. The foreground is the back corner of the garden (currently a compost pile of pumpkin vines covered in chopped hay.

    View attachment 1644
     

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  2. Pragmatist

    Pragmatist Junior Member

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    Today I connected the existing pipe to the bottom tank as the top tank came up to a bit above the gutter level. IBC tanks have a central lid (~15cm diameter on mine but they vary) in addition to the valve/tap outlet at the bottom. My plan was to us this as the drop in with a mesh filter to keep out the gutter muck and mosquitoes.

    So far so good - to a point. The mesh design seemed quite effective at filtering out particulates without impeding the flow too much. The design I used was two layers of plastic mesh with pantyhose in between. The plastic mesh provides the stability and protection from damage while the pantyhose provides reasonably fine filtration. The whole lot is help in place with tight elastic.

    View attachment 1646

    As this photos shows, the lumps are kept out and the water flows through quite freely.

    Lessons learned:
    • fine mud will get caught between the stocking and top layer of mesh. I still haven't figured out how to deal with this. I might end up just leaving the top layer of mesh off and accepting a higher rate of damage to the pantyhose layer.
    • dissolved mud will still get through. I washed out the gutters into the tank and it's now filled with brown water. This is not trouble for our garden watering (as long as it doesn't harm the pump) but would be a concern for those who want the water for drinking.
    • Wet stocking is effectively airtight. The water flowed freely at first but the pressure built up inside the tank pushing the filter into a bubble and forcing all the incoming water to flow off the top rather than passing through the filter. A breather in the tank will fix it and I'm still looking at how best to do that without letting the mosquitoes in.

    View attachment 1648

    The gutter was full of rubbish and the filter seems to have kept most of it out of the tank along with quite a bit of the water. Hopefully future flows (from actual rain) will be much cleaner.
     

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  3. Pragmatist

    Pragmatist Junior Member

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    A nice dump of rain has given me what looks like about 1200-1300L of water to work with. That's only off 1/2 the shed roof because I haven't had a chance yet to plumb in the other side of the guttering :y:.

    This morning it was almost full from rain yesterday and overnight
    View attachment 1651

    So I pushed in a second tank to share the load in case significant extra rain came during the day. Looks to me like a touch more than 1/2 a tank in each with a little more due tonight.
    View attachment 1652
    (yes, that's a 15m roll of 13mm poly pipe connecting the two tanks because I didn't have time to set up the connections properly and I didn't care about slow transfer rates).

    Looks like I'm off to buy 4 more tanks on Monday morning and pump the water out of the wood-based tank that I promised to a friend. I've been putting it off for a while (it requires a 5am start to go there before work).
     

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  4. Terra

    Terra Moderator

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    Dont forget to keep the light out they will go green pretty quick
    Rob
     
  5. Pragmatist

    Pragmatist Junior Member

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    An update:

    I bought 4 more tanks (metal-based) and pumped all the water out of the wood-based tanks. The metal ones stack very nicely although quite a few of the bases are damaged (presumably from forklifts). I've tried to put the less-damaged ones at the bottom of the piles and so far there has been no sign of instability with a full tank of water on the second layer.

    Having seen the height of the stack (a little more than I originally expected, based on a tank height of 1.1m rather than 1.0m) my better half has decided that 3-high would probably upset the neighbours over the back fence. I'm not keen to lose the pressure header tank as it would likely require a more complex battery system with a bigger pump to drive the water directly for irrigation purposes. We'll see how it looks when I put one up there for testing purposes - maybe this weekend.

    I finally connected up the solar panel and pump. The solar panel is sufficient to make the pump go from about 9am to 4:30pm even at this time of year (running straight off the panel) so I'm happy with that. Still need to sort out the circuit properly to regulate the voltage as tilting the solar panel until the pump sounds right is not really a sustainable option :think: The pump connections also need better sealing as the inlet side is sucking in some air and only moving water at about 1/2 the advertised rate.

    Here is is so far with the first 4 tanks in place. It takes a while there to level out the base by hand with a spade and pavers for support.

    View attachment 1666

    So far, so good :)
     

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  6. Ray

    Ray New Member

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    Are you still having issues with the air? A simple solution - plumb some of that spare 13mm pipe from the top of the tank (sealed), down to ground level into a bucket filled partially with water. As pressure in the tank increases the tubing will flow air (think: bubbles, or even better an airlock on a fermentation vessel); while keeping insects, bacteria, etc from coming back up the tubing.
     
  7. aikidesigns

    aikidesigns Junior Member

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    Excellent idea - was gonna suggest it myself. =)
     
  8. Pragmatist

    Pragmatist Junior Member

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    Thanks for checking back in. The air problem doesn't seem to have persisted with normal rainfall rates (instead of the hose) and the tanks ganged together. I'll keep an eye on it though. The solution I had in mind was similar but a bit of fine mesh (old stocking) over the end of a short stub of 13mm poly pipe out the top. Another option could be an old homebrewer's airlock.

    The system is coming together slowly. I'll pick up a final 3 tanks on Monday bringing the total to 9 tanks (~10kL of storage). I decided to bite the bullet and go for a proper battery/controller setup for the solar panel and pump so that will be in place shortly and it should all drive mostly automatically.
     
  9. Pragmatist

    Pragmatist Junior Member

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    It's getting closer to sorted out now with 8 tanks in place with one more to go in and one spare. Both sides of the shed are plumbed in although I still have a 45L bucket catching the leaks from the missing end cap on one gutter. I'll try to patch that up during the week.

    The battery controller works great although I'm still trying to work out if the timer function will let me run it for ~6 hours during the day only. From my read of the instructions it appears to be a night trigger only (once the solar feed drops to a predetermined level. Might have to bust out the Arduino to do the fancier controlling. Meanwhile I'll just keep manually plugging the pump in when I need it to run. As a bonus, the ute battery now stays charged (it only gets driven every few weeks at most.)

    So far there is about 4500-5000 litres of water in the system with lovely, steady rain filling it even further as I type :) 3000L of that is in the second-level tanks and the header tank is waiting for me to connect it up to the outflow taps before I fill it. The system might not completely fill this winter but it looks like going close.

    Photos later in the week.
     
  10. Pragmatist

    Pragmatist Junior Member

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    Well, the 9 main tanks are in place and the solar panel is keeping the ute battery nicely topped off while providing plenty of energy for the transfer pump. It's still not plumbed together completely yet (this day job thing really gets in the way sometimes).

    Now to work out whether the 10th tank fits somewhere around the house to get additional catchment area to transfer up the hill to the shed.

    Sorry for the lack of image - the uploader isn't playing nicely for me.
     

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  11. Pragmatist

    Pragmatist Junior Member

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    Here we go - looks like I was trying to exceed the 95kB file size limit for the server.

    View attachment 1720
     

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