Miscellaneous &Nerd stuff 15 Jun 2006 10:00 am

Rainwater tanks

Here’s a new topic for the Flying Nerd.

You’ve probably notice that I enjoy writing about technology. Formula 1 sneaks in as it’s probably the sport that uses the highest level of technology.

Well, here’s a change of pace – but it’s an interesting use of a combination of simple technologies.

[Lots of pictures on following page – may load slowly…]

The House of Nerds, despite being located deep in suburban Sydney, is not connected to the local council’s stormwater drainage network. The lie of the land in the very close vicinity is such that the stormwater pipe in Nerd Street is uphill (if only a bit) from the building. So the stormwater from the house drains to a seepage pit (swamp generator) in the back yard. In prolonged periods of heavy rain, the water bubbles up from the ground in a few places – maybe I could bottle it as natural springwater…

Anyway… when your friendly Nerd and his family decided, after years of planning and procrastination, to have a new covered deck installed at the back of the house, Council knocked back the plans on the grounds that the increased roof area would collect so much water as to overwhelm the seepage pit. It’s a funny argument, because the deck is only about 5 metres away from the seepage pit, and the area was paved previously, so the new roof would only have moved the water by a couple of metres. But you can’t argue with the Council (trust me).

Council’s proposed solution was to spend (est) $50k digging trenches through three neighbouring properties in order to connect to the nearest stormwater drain ‘downhill’. Needless to say, a bit of Nerdish analysis revealed this to be a ludicrous idea.

Our counter proposal was to install some rainwater tanks to catch the water from the new roof. This proposal, costing around one tenth of Council’s, proved acceptable to the men in shorts and long socks. And so this is what we have built.

Now I know that not many people will be fascinated by pictures of tanks and pumps and stuff — but I’m pretty pleased by how it all turned out. It’s a neat installation. It reduces the load we place on Sydney’s dwindling water supplies. And it keeps some stormwater out of the instant swamp (seepage pit).

First, here’s a view of the overall installation. There are four slimline tanks alongside the new deck. Each tank can contain 750 litres of water.

Overall tank and pump installation

The tanks were supplied by Irrigation Warehouse in Glen Innes. Irrigation Warehouse is an on-line supplier of all things tanks. They gave me loads of free advice and arranged prompt delivery. Recommended.

The green box in the foreground contains a Davey pressure pump and RainBank. The RainBank is a clever device that allows the pump to supply water from the tanks when there is water in the tanks to supply, but when the level in the tanks drops below what is safe to maintain prime in the pumps, the RainBank automatically switches over to supply mains water.

At our house, the pump is connected to our toilets. When we flush, the cisterns fill from the tanks when there’s water in the tanks, and when there isn’t, the cisterns fill from the water mains. Simple, and transparent to users.

Here are some pictures inside the tank box:

View inside tank box

View inside tank box

The RainBank controller is the black box mounted on top of the pump (pump motor is yellow, pump assembly is stainless steel). Rainwater from the tanks enters the pump through the white pipe low down in the box. Mains water is connected to the end of the RainBank furthest from the tanks, and the RainBank output (tank or rain water) is closest to the tanks.

The rainwater travels in a specially marked pipe installed along the side of the house.

Rainwater pipe

Just outside each bathroom, the rainwater pipe has a tee connection feeding through the wall…

Tee on rainwater pipe

… into a new tap on the wall in the bathroom. A flexible hose connects from here to the cistern. Note the requisite labelling – just in case anybody is thinking about drinking from the toilet bowl.

Toilet water supply tap

We now feel ever-so-virtuous when we flush.

But wait, there’s more!

We now have this handy-dandy dual tap arrangement in the back yard (replicated out the front) so that we can use rainwater in the garden.

Garden taps

And still there is more!

Getting rainwater INTO the tanks is no mean feat. We are collecting water from the roof over the deck AND from part of the pre-existing house roof. The overall input side of things is shown here:

Input to tanks

Here’s a slightly closer view:

Input - closer view

The flow is like this… First, the water enters a leaf catching head which filters out leaves, twigs, dead birds and such. (It’s a LeafBeater, for those who are interested.)


From the LeafBeater, the slightly-cleaner water flows into a first flush diverter. The first flush diverter collects the first ten litres or so from the roof and drains it away. This means that the tanks don’t collect the grit and grime that comes off the roof when it starts raining. The photo shows the base of the first flush diverter, with the contents piddling out the bottom. At the top, it just looks like a piece of poly pipe connected by a T-junction.

First flush diverter

When the first flush diverter is full, the now-clean water enters the top of one of the tanks. (The tanks are linked together, so they always have equal amounts of water inside).

Water flowing into tank

(Don’t tell anyone, but when the tanks are full, per Council requirements any excess rainwater goes into the old drainpipe and finds its way to the seepage pit!)

The crowning glory for the whole technological masterpiece is the Levetator water level indicator. This clever beastie uses a system of weights and pulleys to show the level of water in the tanks.


It works like this:


Well, there you have it. Nothing really super-high-tech, but an interesting combination of tried and proven technologies.

And you know what, it all just works (for one tenth of the price of Council’s civil works suggestion).

(By popular demand, here’s The Deck. This photo was taken before the tanks were installed. The tanks are now sitting on the concrete slab you can see to the right of the deck.)

The Deck

39 Responses to “Rainwater tanks”

  1. on 19 Jun 2006 at 11:03 (Sydney) 1.Lizzie said …

    this took a long time to read and you didn’t even put a pic of the deck on!

  2. on 20 Jun 2006 at 7:52 (Sydney) 2.Richard said …

    Lizzie: it wasn’t ABOUT the deck! And it WAS worth the read…

  3. on 25 Jun 2006 at 0:36 (Sydney) 3.David said …

    I’d really love to see a pic of the deck too!
    Is the Flying Nerd married to the Flying Nun?

  4. on 25 Jun 2006 at 7:35 (Sydney) 4.Richard said …

    David, you can come and sit on the deck when the weather warms up. As to the Flying Nun… well she is sometimes a bit batty.

  5. on 29 Jun 2006 at 11:31 (Sydney) 5.The Flying Nerd » Blog Archive » Photo of deck added to article about rainwater tanks said …

    […] By popular demand (well, two people asked), I’ve added a photo of The Deck to my article about rainwater tanks. […]

  6. on 29 Jun 2006 at 11:32 (Sydney) 6.Richard said …

    OK all you deck fans… I’ve added the requested photo.

  7. on 29 Jun 2006 at 12:37 (Sydney) 7.rhm said …

    Nice pipeage.

  8. on 30 Jun 2006 at 9:09 (Sydney) 8.Lizzie said …

    very good, thankyou!

  9. on 02 Jul 2006 at 9:14 (Sydney) 9.Zog said …

    the relief is palpable!

  10. on 04 Jul 2006 at 9:12 (Sydney) 10.Richard said …

    You havin’ a go?

  11. on 12 Jul 2006 at 7:34 (Sydney) 11.Zog said …

    me? never! not the stirring type – just consider me not playing with a full deck. Just a bit of a joker. really. :p

  12. on 01 Nov 2006 at 23:30 (Sydney) 12.Paula Roberts said …

    Getting many world-wide comments? I’m from Georgia (USA) and loved all your fine pictures. You may have mentioned it (and I overlooked it), but what’s your yearly rainfall amount? What’s the square footage of your roof?

  13. on 02 Nov 2006 at 7:51 (Sydney) 13.Richard said …


    The average annual rainfall at the weather reporting location closest to my home is 1135mm. I’m collecting water from around 60sqm (roughly 600sqft) of the roof – about a quarter of the total area. This means that I collect 600L in a 10mm rainfall. That is, in an average-ish month (around 100mm of rain) I should be able to collect 6,000L (assuming that there is always room in the tank to collect). So if we get average rainfalls, I should always have water.

    However, our rainfall is less than average at present. Last month (October) we had only 10mm. The tanks are dry.

    Not many international comments. Glad to have them, though!


  14. on 29 Dec 2006 at 12:04 (Sydney) 14.Beth said …

    Richard, Excellent job! Thanks for posting.
    Beth, from Dallas, Texas

  15. on 06 Feb 2007 at 14:38 (Sydney) 15.The Flying Nerd » Blog Archive » Nerd versus flying insects said …

    […] you read my post some time ago about rainwater tanks, you’d know that our home has a new deck out the back. Here it […]

  16. on 08 Apr 2007 at 0:50 (Sydney) 16.dale hopper said …

    more and more, as time goes on and freshwater dwindles and cost goes up, rainwater can help in irrigation and toilet flushing. Its an ancient idea who’s time has come again. In china and india and other countries, rainwater has always been collected. We, here, in the usa will need to do this more and more to conserve potable water. Here, in my city, cleaning water from the river has a cost and people need to realize that drinking water should only be drank.

  17. on 07 May 2007 at 14:37 (Sydney) 17.Jen said …

    Hi flying nerd, I’m thinking of designing a similar system, could you tell us how much this whole thing cost for you? Thanks!

  18. on 07 May 2007 at 14:46 (Sydney) 18.Richard said …


    The tanks and pump added up to around $A2k. Check out the supplier referenced in the article for latest prices.

    Installation of the whole shebang including plumbing to two toilets and two garden taps was around $A2.5k (lots of copper pipe, many hours!).

    This is not a project that will pay off (financially). I guesstimate that, at current water prices, the payback is around 50 years!

    Nevertheless, it’s good for the planet and for Sydney’s water situation. We draw about 100L per day from the tanks flushing the toilets. Since installing (nearly a year ago) we’ve only used mainswater in the toilets for about one week. Another 1,000L in the tanks would have prevented this – but I just don’t have room!


  19. on 12 May 2007 at 10:31 (Sydney) 19.chris said …

    A good read with pic’s, very nice. I live in St. Catharines, Ontario, Canada. I have been collecting rain water for about 8 years now and have expanded my containers for collecting water for watering the garden. I used to have 2 containers which totalled about 315L . I now have 6- 220L containers (1320L) and have been reading about rainwater toilets. I am just about ready to connect a hose to my downstairs toilet and try it for the summer season. I am working on a valve that I can use to easily change from rainwater to city water. I can almost say for sure that I will be the only person in the city, if not Ontario, that has a rainwater toilet. When I have it finished, I am thinking of calling a newspaper to do an article on the subject. In Ontario they charge the same amount for sewage as they do for the water you use, which make sense, if you use a lot , you’ll be charged the same to clean that water up. I’m not sure if they will look to kindly upon this idea since now they have to process waste that I haven’t paid for. Oh well, onwards and upwards!! Chris.

  20. on 16 May 2007 at 0:20 (Sydney) 20.Sean said …

    This is an amazing system, thanks for sharing!

    I live in Hamilton (Ontario) and am also working on rain flushing… it’s going to be a race to see who is first! Though there may not be many (or any) homes flushing rainwater, there are definitely some public buildings that are already doing it. There is at least one (the new water treatment building) in Hamilton, and I think University of Waterloo has one building that works that way.

    Unfortunately I don’t have a basement toilet, so I won’t have the flushing set up until I work out a pumping scheme. What do you do in the winter? just shut down the collection system?

    I’m thinking of setting up a system with a small secondary tank in the attic which feeds the toilets through gravity. Then when it is low, a pump refills it from the collection tanks (or if they are dry, from city water).

  21. on 02 Jul 2007 at 11:13 (Sydney) 21.Chris F said …

    Loved the blog regarding the rain water tanks. I’m in Minnesota, so I’ll have to figure out a way to have the tank in my basement with a pump. Nice deck.

  22. on 13 Sep 2007 at 12:16 (Sydney) 22.David (Sydney) said …

    Does the Rainwater tank make such noises that bothering your neighbours such as when rainwater is dropping into the tank or while the jump is working.


  23. on 29 Oct 2007 at 9:42 (Sydney) 23.Pablo Bolomey said …

    Nice work where did you get the pump housing box

    Regards Pablo

  24. on 13 Nov 2007 at 19:15 (Sydney) 24.Richard said …

    David: it’s pretty quiet. Pump is noisiest part, but never had a complaint.

    Pablo: local plumbing supplies shop (Reece).

  25. on 07 Jan 2008 at 10:07 (Sydney) 25.rain water tanks said …

    Wow, this is a fantastic setup!

    I work for a gold coast based water tank business an its great to see quality installations being set up. Although the water pump seems a little under powered for its size Im sure it should wash down the car.

    In QLD, the govt rebate is droping back all rebates by Febuary, UNLESS internal plumbing is installed. which means fully plumbed into utilities.

    Gold Coast Water Tanks

  26. on 27 Jan 2008 at 7:38 (Sydney) 26.Chris said …

    Did you look into running your laundry machine with rain water? I’d imagine a regular clothes washer will use 20? gallons per wash. Tho that would quickly drain your tanks unless it was a rainy season.

  27. on 10 Feb 2008 at 21:07 (Sydney) 27.Richard said …

    Robert: pump handles two toilets just fine!

    Chris: the plumbing to my washing machine is difficult to reach — too expensive to connect up.

  28. on 20 May 2008 at 2:49 (Sydney) 28.Jeff said …

    Very Cool… My community has got itself in trouble with the Feds for its out-dated sanitary system and sewage rates are now about double the water rates. Something like this might actually have a reasonable payoff.
    Jeff in Pittsburgh Pennsylvania

  29. on 26 Jul 2008 at 3:54 (Sydney) 29.Terry Barnett said …

    Loved your article and the concept and the photos. Here in Manchester, England, where there is no shortage of rainwater, most houses are 2 storey, with a header tank in the attic. No one has basements here. Is the pump powerful enough to pump the water up 10 to 15 feet or am I underestimating the problems of design and instalation?
    Thanks, Terry Barnett terryb@tesco.net

  30. on 31 Jul 2008 at 20:24 (Sydney) 30.Richard said …

    I believe that the pump is powerful enough to handle a two-storey home. Can’t test it — as my home is single storey.

  31. on 12 Aug 2008 at 7:27 (Sydney) 31.Sean said …

    Does the $A2.5k project cost include the deck? Or is that sold separately?

  32. on 14 Aug 2008 at 9:28 (Sydney) 32.Richard said …

    Deck was more than 10x the cost of the water tank system.

  33. on 24 Nov 2008 at 18:53 (Sydney) 33.Darrell Young said …

    Very nice installation. You have done a great job putting this blog together.
    If you viewers/ readers are interested in a Sydney based co that can supply you with all of you rainwater harvesting needs visit http://www.rainwatertanksdirect.com.au

  34. on 29 Dec 2008 at 17:04 (Sydney) 34.Alexandros said …

    Great work, concerning the tanks an the website.
    I am working on a large scale project, cultivating land of 50 000 sq m and in the long run more than 3000 sq m will be built using bioclimatic architecture, wind turbines etc turning it into a ecological farm.
    I was wondering, since you worked so professionally here, if you have an idea on how i could follow your lead in a larger scale. Do you think Stainless Rainwater Tanks would be a more effective solution or is it too costly?
    My intention is to have a full bio-cleaning sewage system so i’ll be able to use the water and waste as fertilizer, but that won’t be enough for such vast land i’m afraid.
    Keep up the good work
    Alex-Athens Greece

  35. on 19 Apr 2009 at 13:47 (Sydney) 35.Betty Saenz said …

    Great article replete with LOTS of photos!! I saw all those pictures that said “not for drinking”. Here in Texas there are many homes that use rainwater for EVERYTHING including drinking and cooking.

  36. on 06 Aug 2009 at 8:48 (Sydney) 36.Richard said …

    The ‘not for drinking’ signs are a legal requirement. There is no treatment of the roofwater, so it contains whatever pollutants may be washed off the roof by the rain. Yes, it’s probably pretty safe…

  37. on 18 Apr 2012 at 3:17 (Sydney) 37.Rainwater Tank said …

    This is very helpful article. You gave the right form or installation of rainwater tanks and it was properly installed to your water system in your toilet.

  38. on 27 Apr 2012 at 9:43 (Sydney) 38.Jonathan said …

    Great system, well installed, nicely photographed and explained. Thank you.
    But the wire in your deck balustrade runs horizontally – surely that can’t be right? or is because the deck is less than 1m off the ground??

  39. on 27 Apr 2012 at 10:01 (Sydney) 39.Richard said …

    Jonathan: the stainless steel balustrade wires are legal on a low deck like this.

    Thanks for reading.