How to Build a Self-Cleaning Rainwater Tank from a Wheelie Bin

Wheelie bin as a water storage container

You can never have enough water storage, and a spare wheelie bin makes a handy water carrier that can easily be moved around (when it is empty of course, a full one can’t be moved!)

This design was my first ever water storage solution, and being rather experimental, I kept on adding to the design to constantly improve it,and this is the final result.

In case you’re wondering how this is any different to any other small water tank design, this one is actually self-cleaning. It has an inbuilt siphon to pick up sediment from the bottom and wash it out of the overflow outlet.

So, this is really two instructions in one – how to convert a wheelie bin into a water tank, and how to build a self-cleaning tank system that you can adapt to any tank system, so you can do either or both!

NOTE: To avoid unnecessary repetition, the construction steps in this project are slightly abbreviated, as I’ve already covered the construction methods, tools and techniques in great detail in the previous project, a modular, expandable water tank system – listed here Recycled Plastic Drum Rainwater Tank under “DIY Instructions“.

Design Theory

My intention with this project is to briefly take you through a simple water tank design, and then explain the construction of a basic self-cleaning system that removes sediment from the bottom of the tank automatically when the tank overflows. This self-cleaning design can be adapted to any water tank, including full sized commercial water storage systems.

In fitting in with the permaculture principle of having things serve more than one purpose, this design uses the one tank function (an overflow outlet) to achieve two purposes:

  1. To redirect excess water that cannot be stored to other storage locations or to the garden
  2. To remove stagnant water and dirt from the bottom of the tank

Typically, overflow outlets sit high up near the top of the tank, so when they fill, the excess clean fresh rainwater coming in pours straight back out of the side of the tank, usually via a flexible pipe, to somewhere else where it may be utilised, and preferably, anywhere but the stormwater drain.

…if you think you have no more places to store water, consider the most obvious one that nature uses…

As an aside, if you think you have no more places to store water, consider the most obvious one that nature uses – your soil! Soil has a capacity to hold a considerable amount of water, so if your tanks are full and rain is coming, pump your tanks out into the soil, and let the rain refill them, rather than letting perfectly good stormwater go to waste. Unless you’re in one of the higher rainfall areas of Australia, you won’t have to worry about turning your garden into a swamp…

Now, the problem with traditional overflows is quite obvious, you end up dumping clean, fresh, oxygenated water that has just come in straight back out, while leaving the old, stagnant, anaerobic (oxygen-deprived) water sitting in the bottom of the tank with a thick layer of sludge and sediment, which makes for a nice breeding place for the less-friendly types of bacteria.

If the new fresh water could push out the old stagnant water as it comes in, and push out some of the dirt and sludge out with it, then this would be ideal! And that’s precisely what we’re doing here…

The diagram below shows how it works.

  1. Rainwater coming in causes the water level to rise. It cannot escape from the tank until it reaches the level of the overflow outlet.
  2. If the overflow was just a hole in the side of the tank, when the water level rises just above the level of the bottom edge of the hole, it would naturally trickle out from the top.
    By fitting a pipe (the “riser tube”) to the hole and running it to the bottom of the tank, we still have a hole in the side of our tank, only the water has just got a longer way to travel now to get out, from the bottom of the tank, all the way up.
  3. Now, when the water level rises in the tank, it rises an equal height in the riser tube. As soon as the water level inside the riser tube reaches the horizontal or level section where the hole is, it is sucked up from the bottom of the tank and flows out through the overflow pipe to the ground.
  4. The suction through the pipe works like an underwater vacuum cleaner and draws out the dirt and sediment out with the water at the bottom of the tank.


For anyone who has ever used a piece of tubing to siphon liquids from one container to another, this should look quite familiar. Without the air inlet at the highest point of the riser tube, it’s just one great big siphon. If you don’t include an air inlet, then once you get any water flowing the overflow, it will continue to flow out by itself until it empties all of the water! Believe me, it happened, and then I realised I needed to include a air inlet (a simple “T”-shaped fitting) to work as suction breaker to prevent automatic siphoning. This way, when the water level falls below the overflow outlet level, air comes in from the top via the air inlet and interrupts the flow of water. Simple, but effective!


The construction of this unit is fairly simple and straightforward, and you can build a basic water storage unit by completing only a few of the steps. The rest are optional, and can also be completed at any point in time to add extra functionality as desired.

Step 1 – The Bin!

Firstly, you will need a wheelie bin, either new or recycled, to hold the water.

Make sure that the bin is in good condition and has no crack or damage, as a full wheelie bin is rather heavy (220kg for a 220litre bin – water weighs 1kg per litre) and may burst if it is weakened.

You can really adapt this design to use whatever water container you wish.

Picture 7-002
Wheelie bin (220 litre unit pictured) or any other suitable container

Step 2 – Inlet Filter – Water In!

A medium sized 20cm aquatic basket pot (used in water gardens and ponds) serves as the water inlet filter.

This strains out any large debris, such as leaves, and prevents mosquitoes from getting into your water tank and breeding in there.

Picture 7-003
Medium size aquatic basket pot (20cm wide)

Step 3 – The First Cut

A hole needs to be cut into the lid of the bin to fit the water inlet filter (the aquatic basket pot). Use an electric jigsaw or any other suitable hand saw that can cut curves, such as a keyhole saw.

Note – the hole must be small enough so the pot cannot fall through! The pot has a wider lip, which will hold the pot up.

Picture 7-004
Cut-out made with jigsaw, smaller than the lip of pot

Step 4 – Fit Inlet Filter

Set the water inlet filter (the aquatic basket pot) into the hole in the lid.

It should be a nice snug fit with no gaps.

Picture 7-005
Basket pot set into wheelie bin lid

Step 5 – The Outlet – Water Out!

Now that we can get water into the bin, we need to be able to get it out too! To fit a tap of some sort to the tank you will need to use a 20mm threaded tank adapter, pictured below.

Picture 06-08
20mm Threaded Tank Adapter

Step 6 – Drilling Tools

To drill a precise hole that will be watertight with the threaded adapter fitted, you will need and electric or cordless drill and a holesaw as pictured below.

The outer diameter of the 20mm threaded tank adapter is 25mm, and this will make for a nice, snug fit.

Picture 06-03
Electric or cordless drill with 25mm holesaw

Step 7 – Mark Drilling Location

Mark where the hole is to be drilled on the wheelie bin – I have located mine 10cm (4”) above the bottom edge of the front, in the centre. You can choose to place the tap wherever you require it. If space is an issue, and you need clearance from the front, you can place the tap on the side, for example.

Step 8 – Drill Hole

Drill the hole at the location marked. If there are any rough edges after the hole has been drilled, smooth them off both inside and outside the tank with some sandpaper.

Step 9 – Fit Outlet

Fit the 20mm threaded tank adapter, and tighten it by using an two adjustable spanners, on on each side, that is, one inside the tank, one outside it. Tighten in reasonable but do not over-tighten.

Step 10 – Fit Taps

To turn the water on and off, you’ll need a tap or ball valve. The ball valve opens fully by turning the lever a quarter turn, it’s a nice convenience, but costs a lot more than a common garden tap, which will do just as well.

Make sure you check that the tap or ball valve screws into the 20mm threaded tank adapter when you purchase the parts – if they don’t you might need some additional fittings, so make sure you have these before you commence!

Picture 06-08d Picture 06-08b

Ball valve (left) or Tap (right)

This is my completed outlet tap setup. I’ve added a few more fitting so I can connect a garden hose straight to the click-fitting on the end.

Picture 7-006
Ball valve fitted to threaded tank adapter

At this point, you have a tank with an inlet and a tap, it will collect and dispense water, and if you’re happy with that, then your project it complete!

Now, if you still wish to add a “few more bits”, then read on…

Step 11 – Fitting an Overflow

An overflow is simply another outlet placed higher up, on any one of the sides of the the tank, that lets excess water out when it reaches that level. It prevents water overflowing out of the top of the tank and flooding the surrounding area once the tank is full. By connecting a pipe to the overflow outlet, you can redirect the excess water where you want, back into a drain, to the garden or lawn, another tank, wherever you like.

Simply mark a spot on the side of the tank near the top, at the level where you don’t want the water to drain out. Then drill another hole at this point with the drill and holesaw, fit another 20mm threaded tank adapter, and screw on a 20mm elbow fitting (“L”-shaped) to point the outlet down. Add whatever fittings you need to connect your hose of choice.

Picture 06-31 Picture 06-30
Overflow fitted to side of drum (left) and flexible “washing machine” style hose connected to overflow outlet (right) (Pictures from previous project Recycled Plastic Drum Rainwater Tank )

If you’re happy with a basic overflow, which is what I use on my main water collection setup, then your tank ifs ready to go and “flood-proof” too!

But still, if you want to keep on going, there’s a few more things to do…

Step 12. Setting Up Self-Cleaning Function

The picture below shows the siphon cleaning system set up inside the wheelie bin tank. The overflow sucks water and sediment from anaerobic region at the bottom of the tank and flushes it out to the stormwater drain or elsewhere.

NOTE: in the picture below, the overflow on the left is capped off and turned upwards because the tank was disconnected from use temporarily and this is a preventative measure to stop mosquitoes getting in, and water sitting long term in the fitting and becoming stagnant – it is normally pointed downwards, with an overflow pipe connected to it, as shown in the rest of the photos below.

Picture 7-007
Self-cleaning siphon overflow to remove dirt and sediment from tank

To set up the overflow siphon:

  1. Connect a 20mm “T-piece” to the inside of the tank adapter as a suction breaker to let the air in so it doesn’t self-drain the whole tank.
  2. Fit a 90 degree or elbow join (“L”-shaped) to point the pipe to the bottom of the tank.
  3. Fit a long 20mm riser tube that reaches to the bottom of the tank(approx. 60cm long for a 220 litre bin) to the elbow join – you may need to cut it to length, and it’s OK if it sits at an angle, as long as it reaches the bottom.
  4. Cut notches in the end of the riser tube that rests on the bottom of the tank, as shown in the diagram below, to assist water flow and sediment collection while preventing blockage.

The riser tube rests against the bottom on the tank, and has slots cut into the end of it to improve flow and sediment collection.

Step 13 – Position Tank, Connect Overflow Hose and Water Inlet

Locate the Wheelie Bin water tank near your collection point, such as a stormwater downpipe.

If you haven’t connected an overflow hose yet, this is the time to do it!

Picture 7-008
Fully set up Wheelie Bin tank with siphon cleaning system and overflow pipe

You can collect the rainwater directly from a stormwater downpipe, or from a rainwater diverter that you have fitted to your stormwater downpipe.

In the pictures below, you can see how I’ve set the tank up. I have connected a flexible 40mm agricultural pipe (aka Ag pipe or Aggie pipe – the non perforated variety, that is without the holes!) to a rainwater catcher/first-flush diverter assembly. The end of the 40mm ag pipe just rests inside the inlet filter basket.

Picture 7-009

Here’s the whole assembly, from gutter to bin!

Picture 7-010

That covers the setup of a basic working system that will get you up and running with rainwater harvesting. As you can see from these instructions, you can choose to make it as simple or as complex as you choose. The complexity increases the convenience factor, but also escalates the setup costs accordingly.

The best advice is to start simple, and expand it from there to suit your needs. That’s probably the most efficient way to do it, and the least confronting too!

To illustrate the point, here’s how my single wheelie bin system grew to my current setup.

The little system you’ve just seen served me well for over a year, then I started experimenting further with a modular, expandable system, using recycled plastic drums, which were cheaper and more durable than wheelie bins.

As is visible on the right, the trusty wheelie bin still in service, though a little out of place.

Picture 06-00

The water storage system was expanded yet again. This is my water storage system today…

Picture 06-00a

The wheelie bin water tank is still in service though, it sits close to the blue tanks (just outside the view of this photo) so I can pump extra water into it when my storage is filling up.

The six blue tanks hold 1320L (6 x 220L) and the wheelie bin adds another 220L, taking the total capacity to 1540L. It accounts for almost 15% of my water storage capacity, so it still does its part in the grand scheme of things!

And to think it all started out with a wheelie bin…

50 thoughts on “How to Build a Self-Cleaning Rainwater Tank from a Wheelie Bin

  1. Thanks for the detailed instructions, and for your great site overall! I posted this link to Twitter. I lived in an urban caravan park for some years and collected rainwater off the roof of the laundry-room there. One rainy summer I met 100% of my water needs from rainwater. WIth more containers for storage, I could have done that even in the less-rainy times.

  2. I aquired extra 240L wheelie bins and checked through your website and walla! You have a fabulous instructions on creating additional water storage. I cannot speak highly enough of your website as a resource. Love your work.

  3. Thomasina says
    Hi I have just finished reading your site about how to make a home wheelie water bin and more. You can choose how far you want to go or how much water you want to collect, so I am keen to make one up for my centre.
    There would be many uses for it and knowing that it is natural and clean makes it even better. Thank you ever so much for your clear instruction to make a Recycled Plastic Drum Rainwater Tank. Awsome…..

  4. Very good, but would the overflow water not go through the open tee at the top rather than from the bottom of the tank?

    1. Hi Rick,

      The top of the tee-fitting is higher than the overflow pipe, so when water rises to a certain level, if flows along the horizontal part of the tee fitting and out of the overflow pipe on the side. Once water flows, it can only draw on more from the bottom.


  5. Self Cleaning Is Excellent Idea – Would There Be any advantage having two Risers Say One Each Side of The Bottom Of The Container – Would It Improve Cleaning??

    1. Using one riser gives a stronger suction effect, using two risers will in effect halve the force of pull in each one and won’t pull up the sediment as easily. It’s the force of the water rising upwards that carries the debris up off the bottom.

  6. Very good idea.

    Wondering if you have seen the product tankvac.

    Same principle as yours but more for larger tanks, would like to know if you could build diy, as $300 seems on the steep side

    I love the idea of self cleaning as I live on rural property and only source of water is rain water.

    I see some rain water tank sizes and wonder about stagnation, people seem to have a large amount of rain water storage of over 150,000 litres these days,



  7. Hi, I just learned of your site from Geoff Lawton’s online PDC. Your work is stupendous! I love your site, it’s wonderfully chock full of information! I have some questions regarding the self-cleaning siphon. For a multiple tank system like yours, do you install a self cleaning siphon in each of the tank or just the first one? Would the siphon work as well for the second, third, fourth, etc tank or would the siphoning pressure get halved, quartered, etc?

    1. Thanks for your praise! With the multiple water tank system I find that the dirt really just accumulates in the first tank, and only the first tank really needs an overflow pipe, so that’s where you would install a self-cleaning siphon.

  8. Hi. You have such a wonderful, very informative site. We just recently purchased an acre property in Central Florida, USA and i have been researching on the best use of the land. I am very interested in rain harvesting systems as well as greywater systems. I would copy your rainwater harvesting system, do you also have a diy greywater system? Any info on such? Thanks. Tess

  9. Brilliant instructions and diagrams. Thanks! I often get halfway through such “How Tos” and give up, overwhelmed by technical details, but yours was clear right to the end and left me feeling confident that it not only made sense but that I could actually do it too. Have some odd bits of guttering and pipes lying around here so think I’m going to change a few components and give it a go. Just need to source some recycled bins here in NZ.

  10. One thing use pex its a flexible plumbing pipe that will not burst when frozen or bent great for this project very easy to use and very resilliant will not change anything about the system just make it a little more durable for more extreme climates. as a pvc pipe break could cost you all your water.

    1. Good tip if anyone is using PVC pipe. There is no PVC pipe used in this design, hope that helps!

  11. HI there, thanks so much for these instructions, I could find info of people trying to sell me such a set up, but no one seemed to want to say how to make your own!

    I have one question, which is what kind of water pressure do you get from the tap on the wheelie bin? Is it strong enough that you can stand up and hose the garden, or do you need to empty the water into buckets? Thanks!

    1. When the tank is full the pressure is quite high, I’ve used it to water the garden with a very long hose and it works fine. The water pressure is far less than mains water pressure as it’s gravity fed but it does work. As you would expect, as the water level drops, so does the pressure. When the water reaches the bottom, I just lay the hose on the ground and let the remaining water trickle out slowly on its own into a garden bed or beneath a tree.

  12. I am curious if the outlet end of the overflow siphon pipe needs to be lower than the inlet end of the suction vacuum tube inside the barrel?

    1. The outlet pipe doesn’t siphon because of the air inlet that is fitted at the top of the outlet pipe. Water flows out of the outlet pipe whenever the water level goes higher than the level of the outlet pipe itself, in the same way that it would come out if there was a hole at the side of the bin where the outlet pipe sits, whenever the water goes past that level, it flows out.

      The beauty of this design is that when the water goes above the outlet level, the water that it flushes out first is the water at the very bottom of the bin, where the dirt sits, making it self-cleaning.

      If for some reason you wanted the tank to siphon, leave out the air inlet at the top of the outlet pipe, or seal it, that would make it a self-emptying tank! In that case, yes, connect a pipe to the outlet that sits lower than the inlet end that sucks the water up, and it will work perfectly as a siphon!

  13. Thanks for your details instructions. After seeing the Tankvac clip my feeling was it was just physics & I could build the same thing but needed to confirm the details – glad I was diligent in my search ’cause I found your site – Gratitude for your knowledge & experience giveaways

  14. Hi.
    We excitedly purchased new rainbarrels when we purchased our home but the overflow has never worked out and we don’t want to risk the overflow damaging our foundation. The barrel we purchased just had a knob near the top to cut off to attach a hose for overflow or to direct to another barrel (we sadly don’t have room for that) and it has never really worked out. The hardware store sold us this plastic piping that we used hose clamps on however the plastic piping just became brittle and cracked. I am hoping we can adapt to your overflow design. (I plan to print off your instructions as we head to the hardware store!)
    What size hose do you recommend for the purpose of quick overflow redirection and are the 20mm threaded tank adapter and 20mm elbow fitting (L-shaped) hard to find? I thought my husband was trying to find similar pieces in the past and had difficulty. How durable was your washing machine style hose over the course of a summer?

    Thanks for your guidance! I hope to set up 3 more barrels around the house this summer if we can just make this 1st one work! 😉

    1. The 20mm fittings are common and the washing machine hose has lasted many years and is still going well.

  15. I love your site. Thank you for the great information! I do have some questions about the multiple barrel setup. How are the barrels connected? Just from the outlets on the bottom? How does the water flow from one barrel into the next. Sorry but I can’t see anything else connecting them. I currently have two barrels hooked together joined near the top so one acts as an overflow into the next. Is there something similar on yours that doesn’t show in the pictures? I apologize in advance if this is a stupid question. Thanks.

    1. Thanks for your comments!

      Yes, you’re correct, the barrels are all connected together from the outlets on the bottom of each barrel. As the rain comes in and fills the first barrel, it flows out of the outlet and fills all the tanks until they are all at the same level. The only overflow is on the first barrel that the rainwater flows directly into, and the overflow pipe goes to the garden because when the first tank is full, they all are. Hope this helps 🙂

      1. Hi, we are on a rural property with multiple rainwater tanks – just a tip – never connect tanks together at the base – always connect via overflows – this allows the first tank (water in) to be a settling tank where debris builds up but more importantly if one tank or pipe leaks it only empties one tank, not all of them…..

      2. Thanks for your comment, yes, that’s an excellent idea if you have large water tanks, and the overflow pipes are a very large diameter. With the smaller 250L (44 gallon) plastic tanks, when I first built them, they were all connected via overflow pipes using 20mm (3/4″) tank spigots and polypipe, but when it rained hard, the narrow overflows wasn’t able to drain fast enough into the next tank, so a lot of water overflowed out of the top of the first tank onto the ground. It’s possible to use larger diameter tank spigots, pipes and connectors, but this gets very expensive when connecting many small tanks together. Having the tanks connected at the bottom allows me to draw water from all of them via gravity, without a pump.

        For big rainwater harveting tanks, I agree with you 100%, connecting them via the overflows using large diameter pipes is the better way to do it.

  16. I I would like to know what the prices of the blue 240 litre containers and where can I get hold of them and do they deliver

    1. That’s a very hard question to answer because we’re an international website, we have readers worldwide and I can’t assume anyone lives in the same city, state or country as me!

  17. Great tutorial and love your set up. Can you explain if and how the bins are connected to each other please? I’m assuming you have some sort of set up whereby when the first bin is full the water diverts to the second and so on. Looking at the photo it seems all the overflows are connected but l’m not sure how this would fill the bins further down the chain. Many thanks

  18. This is an excellent idea for a ‘stealth’ water tank. In some cities in New Zealand the councils are studying aerial photographs and if they spot you have a water tank your sewerage charge increases. They assume you may be using this water in the house and sending more water into the public system!

  19. As per many other comments, your idea is great. I wish to install the system in our 5000 liter house tank with a diameter of 2.1m. Being larger than a wheelie bin is it better to position the riser tube (100mm dia. in my case) in the center of the tank. The other option I have seen on another website is to place a pipe with ” suction holes ” across the diameter of the tank at the base. Please advise if either or both of these options will help. Many thanks

    1. Since you want water to be drawn across a wider area to clean as much of the bottom of the tank as possible, it would be better to place a pipe with suction holes across the diameter of the base of the tank. If the riser pipe is in the centre, the setup will look like an inverted T-shape, if the pipe is place on one side it will look like an L-shape. I was thinking that you might have to cap the ends otherwise most of the water will flow in from the large end openings and less through the smaller holes. Let us know how it goes!

  20. I have used your self cleaning design adapted to 2 gravity flow household water systems with remarkable results.

  21. Hi Angelo, thanks for showing this idea. I have a slightly different version that works a treat. It’s very, very simple requiring only one length of PVC tubing. No fittings required. Is there any way for me to upload a pic to describe it?

  22. Fantastic. I’m actually currently adapting this idea – the siphon pulls from the bottom of a 220 elevated barre (which already acts as an overflow for another system!)l, then dumps it in the top of a three stage water filter (gravel-sand-charcoal) which then trickles into a smaller drum and gets used for seedlings / topping up the hydroponic systems.

  23. Good idea to siphon the bottom, I can use that both for my wheelie tank & my 5000 one too, cool idea
    I wonder why tanks dont come with siphon on purchasing?

  24. Hi Angelo
    On some commercial versions of this vac system they have what is referred to as a syphon generator on the outside of tank which is a short looking pipe. This seemingly having the effect of increasing the flow rate at the outlet. Can you tell me if your instructions will generate enough vacuum to forcefully release the sediment filled water from a larger 10000L tank.

    1. Hi Peter, thanks for your question. I didn’t base this design on commercial systems, I just worked it out on my own from basic principles, around ten years ago. In the initial design, the siphon worked brilliantly but it didn’t stop once it got started until it emptied the whole tank, simply because I forgot to add the air inlet which breaks the vacuum when the excess water has drained out via the overflow. This design works presented here works on the small scale of a wheelie bin tank.

      Your question prompted me to go and look at how the commercial systems sold currently actually work, and I did notice some differences. The commercial ones are designed for large tanks, so the inlet pipe sits horizontally on the floor of the tank and runs its whole width, to draw up sediment across the whole breadth of a large tank, this is an important feature for a large scale tank.

      The short pipe you mention outside the tank is nothing more than a wide PVC overflow pipe, and because of the large volume of water rushing out, due to its weight a high pressure is created in the siphon. The only thing that’s different is the ‘flow generator’ attached to the end of the overflow pipe. What does this component do? Looking at the technical brochure of one such commercial product, I found the following information – “…uses a patented Flow Generator which removes air from the pipe carrying the overflow water”. I’m guessing when using such a large bore overflow pipe, air must be evacuated so the pipe can fill with water to generate the full flow of water in the siphon. Looking at the patented design, the overflow pipe contains a restriction device inside it which creates enough fluid flow turbulence to dissolve the air back into the water within the outlet of the siphon.

      If I were building a similar system to a commercial one for a large tank, I would use an inlet pipe along the bottom with holes along its length and the end needs to be sealed so water is only sucked in through the holes. Perhaps something like slotted agricultural drainage pipe (Ag-pipe) may work, otherwise you’ll need to drill a length of fairly thick irrigation pipe for the purpose. Hope this helps!

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