My Rainwater harvesting system

Hi,
Just thought Id share how I designed my current rainwater harvesting system , in case it offers ideas for others.
-roof area 370 m2
-Storage tanks 50 m from house
- wanted underground system for various reasons.
- Want easy-to-clean entry-filter.
- Long distance to collection point means 'first-flush' option would have not worked well for wet-system.

Answer:
Figure below shows 5kL tank and ONE of the two identical feed systems.
- 2 entry points to a small nearby tank ( feed from gutters at opposite sides of house), then transfer pump to main tanks.
- Above ground filters ( 2 x 90mm dia), just before tank inlets ( on tank side-wall, at top). Water enters from filter bottom as shown in figure.
- the 2 underground sections each have only 2 45-degree bends, and access covers on ends. THis will allow easy deep-cleaning at some point.
- I Can drain entire underground system with transfer pump via single tap ( i am thinking of automating this also).
Notes: THe first-filter was the biggest concern for me. I knew it would need cleaning regularly, but climbing atop-tank isnt ideal. The 'first-flush' concept wouldve requred a lot of water to go to waste to be effective.
At first I tried a spring-loaded "flip-out' filter from bunnings , which I installed on the horizontal beam before inlet, it worked fine for a while ( flip-out, clean with hose, flip-back)., but quickly become leaky to the point of big concern.
Im currently trying out this new design as shown, with 2 points:
- The overflow is essential incase the fliter is clogged
- The filters are glued permanently in place. They are actually the 'over-flow' anti-mozzie filters.( bunnings) Its very easy to clean - just squirt water down top of inner-90mm pipe. ( Although gravity should keep it somewhat clean natural, as it will fall down unless physically stuck in filter. ( probably will happen )







Rain inlet filters Ive tried. Gave up on middle one. Now using one on left ( Image from rainharvesting-com-au )

Just an after thought: Of course the fine sediment will go through the filter, and slowly build up in the 5KL transfer tank. Ill need to vacuum that out every few seasons.

It is always good and interesting to see improvements on archaic sub-standard charged systems.

Some questions.


Is the entire roof area diverted to the tanks and what is your 1:20 ARI?

So there are two 90mm pvc stormwater pipes charged pipes?

What do you mean by collection point and why couldn't you have fitted first flush diverters?

Are leaf diverters fitted to the downpipes?

Hello. This system looks great but I couldn't see any mechanism to stop stormwater backflow.

I'll add a pic to help.
SaveH20:
1a. Not sure of my 20:1 ARI . Im near Gawler SA. BOM Rainfall SIte says about 2% chance of filling 5KL tank in 4 minutes assuming tranfer pump doesnt turn on.
1b. Entire 370M2 Roof is diverted.
2. Yes 2 charged pipes.
3a. "Collection point' = the 5KL tank right next to house.
3b. Ok - this gets a little technical...our house is over 3 times longer than wide. , and the tank is on a narrow end. Hence the underground volume of EACH long ( over 35 Metres ) 90mm pipe before the first tank is about 240 Litres., meaning crap that falls on the roof, and flows through, wont arrive at first tank until that volume has passed. There's 2 pipes, so a 'properly-working "first-flush " system should loose over 480 litres-ish to "Flush" before any actual "fresh" roof water arrives. I guess its possible to fit individual diverters under base of nearly all of the down pipes ( I think there's 9 ) , to somehow avoid loosing the underground buffered water. ?
Rather than disperse this water, I chose to hold it all, and filter on-tank-entry.

4. Im lucky to have no trees nearby. Im working on the 'suck-it-and-see' approach... I may add these if/when later I believe necessary.

rantapawan:
Im not sure how stormwater could flow backwards. The transfer-pump has valve . THe down-pipes from Gutter only have natural (open system) equalisation through to top of first-tank feed pipe , which run up to a hieght approx 2 foot below gutter.