Browse Forums Landscape & Garden Design 1 Jul 30, 2012 9:20 pm Hi all, just wondering whether something like this is possible, and if so what hardware would be best to use. We have a water tank with a 50mm PVC overflow pipe which currently goes nowhere due to logistics in getting it to the nearest storm water drain. We were thinking of connecting a 50mm greywater pipe or agi pipe (with slots) to this and running it 20 metres down the side of the house as a kind of drip irrigation system. Would this be advisable and would the water distribute pretty evenly over that 20 metres or would it all accumulate towards the beginning of the pipe (I suppose it depends on pressure)? Would it be better to use the sealed greywater pipe and drill some holes in it, or maybe some 19mm poly pipe, or would we suffer pressure issues? Ultimately we want some way of distributing tank water overflow from a 50mm outlet over around 20 metres. The ground is pretty flat. Any ideas? Re: Using tank overflow for drip irrigation 2Jul 30, 2012 11:47 pm Far better idea to plumb the extra water back into the home. Pay for less scheme water in winter to offset the use in summer. Relying on the tank water for the garden is not the greatest. You'll need the water when the resupply to the tank is at its lowest. Its gong to need to be a very big tank to supply the garden. Very big. Re: Using tank overflow for drip irrigation 3Jul 30, 2012 11:51 pm The water will accumulate near the head of the line. If you use netafim integrated drip line it will be distributed evenly. The problem you have is that the ground will already be wet if the tank is overflowing. Can you maybe add another tank instead? Re: Using tank overflow for drip irrigation 4Jul 31, 2012 2:31 am It depends on how big the holes are. If they're small enough, it will drip all the way. With that said, I'm with Fu on this: When the tank is overflowing, there's usually no need to have it, unless you want to water somewhere where rain can't reach naturally, or if you want to make it into some sort of waterfeature - the latter could be nice, depending on how you design it. Using tank overflow for drip irrigation 5Jul 31, 2012 8:52 am Thanks guys. I actually have 4 1000 litre tanks connected together and I'm out of space to add any more I understand the issue of watering ground that's already wet so that's why I thought a drip line might be best so it can be distributed relatively evenly during a downpour. It's just a logistical issue plumbing it back into the storm water drain. Re: Using tank overflow for drip irrigation 7Jul 31, 2012 1:01 pm Try the netafim rain water pipe. Your local retic shop can help you with that. Re: Using tank overflow for drip irrigation 8Aug 07, 2012 7:47 pm The drip line would need to have the same discharge capacity as the overflow pipe's maximum flow during heavy rain. At all other times, the discharge would not be evenly distributed. There are devices available that substitute as the tank's overflow when the tank fills, eliminating the need for a tank overflow. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Using tank overflow for drip irrigation 9Aug 07, 2012 7:54 pm SaveH2O The drip line would need to have the same discharge capacity as the overflow pipe's maximum flow during heavy rain. At all other times, the discharge would not be evenly distributed. There are devices available that substitute as the tank's overflow when the tank fills, eliminating the need for a tank overflow. I think I'll find a way to get it back down the storm water drain. What is this substitution device? How would it eliminate the need for an overflow? Re: Using tank overflow for drip irrigation 10Aug 07, 2012 8:03 pm Water is fed into the tank through a side inlet and not through the top inlet. The device is height adjusted to divert slightly below the overflow mesh, this stops the water flowing to the tank once the tank fills. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Using tank overflow for drip irrigation 11Aug 07, 2012 8:16 pm SaveH2O Water is fed into the tank through a side inlet and not through the top inlet. The device is height adjusted to divert slightly below the overflow mesh, this stops the water flowing to the tank once the tank fills. Ok that makes sense, but it wouldn't work in my case as the tank sits below the storm water gutter (which incidentally *only* runs into the tank any nowhere else, hence my problem). Re: Using tank overflow for drip irrigation 12Aug 07, 2012 8:29 pm They fit into the downpipe and there are 3 that l know of. As long as the overflow heights are adjusted correctly, you could harvest an infinite number of downpipes and the tank will never overflow. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Using tank overflow for drip irrigation 13Aug 07, 2012 8:37 pm Interesting, you wouldn't have a link or product name by any chance? The problem is the main gutter flows directly into the tank, there's no down pipe that's connected to storm water. That means the water has to go somewhere and if the tank's full it can't divert anywhere else. Re: Using tank overflow for drip irrigation 14Aug 07, 2012 9:31 pm That is an interesting situation. I assume the gutter's roof harvest area is not big, otherwise a 50 mm overflow would not cope during heavy rain. Have you got a downpipe that you could divert the overflow back to? Downpipes have a lot of capacity to take additional water fed in at the bottom as downpipes carry a lot more air than water. A 50 mm charged pipe can generate a high flow rate and diverting the overflow even 30 metres with a 1 metre head will provide an unneeded potential flow rate of around 200 lpm. You could use 32 mm LDPE, depending on the required maximum flow rate. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Using tank overflow for drip irrigation 15Aug 07, 2012 10:52 pm That's the main issue in that I don't have a downpipe nearby. I'll divert it to one further away but it's just a logistical problem. By the way the roof area is 25m^2 and it collects via a 65mm pipe into a tank with a 50mm overflow that goes nowhere. Kind of strange but that's the way it was when we moved in. Re: Using tank overflow for drip irrigation 16Aug 08, 2012 12:08 am It would take 160 mm of rain on the roof to fill all 4 tanks and this leads me to ask what you use the harvested water for. If the tanks over filling in winter is a problem, maybe just slowly drain some off during dry periods for mitigation as it sounds like playing around with an overflow pipe will be messy. Melbourne has been wet until last month and La Nina officially finished a couple of months ago. The prediction for a return to El Nino is about 70%. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Using tank overflow for drip irrigation 17Aug 08, 2012 1:16 pm I'll be running irrigation for new buffalo turf that will be installed in spring and have a reasonably large veggie area. Of course over the last couple of years even a 1000 litre thank would have been enough. Re: Using tank overflow for drip irrigation 18Aug 16, 2012 11:34 pm The last couple of years have been La Niña years. When the dry El Niño returns it will bring the dry again and that means available tank water maybe compromised in summer. Re: Using tank overflow for drip irrigation 19Jun 21, 2023 9:20 am SaveH2O The drip line would need to have the same discharge capacity as the overflow pipe's maximum flow during heavy rain. At all other times, the discharge would not be evenly distributed. There are devices available that substitute as the tank's overflow when the tank fills, eliminating the need for a tank overflow. Hi SaveH2O, I realise this is an old thread but I have a related question please. We purchased a small water tank (2500L) for our animal barn (roof = 26m2). Water from the roof enters the tank via a 90mm pvc pipe. It currently has no overflow pipe and I need to remedy that asap as the overflowing water is ruining the tank foundation. The overflow outlet is 90mm but I was thinking of reducing that to a 50mm pipe and then running the pipe into a hedge 6m away. We’re actually thinking we’ll use about 6m of 50mm pvc and then connect it to a smaller poly pipe with holes in it. We’re not fussed if the water doesn’t travel far, we just don’t want it to fall around the tank. Do you think a 50mm overflow pipe would be sufficient in size to prevent the tank overflowing from the inlet? I would prefer to use a 50mm pipe (as opposed to a 90mm pipe) if possible as we’d like to partially bury the pipe, which will be easier to do with a small pipe. We can’t fully bury it unfortunately as there isn’t fall to the hedge. TIA Re: Using tank overflow for drip irrigation 20Jun 21, 2023 12:46 pm You would need to convert the 90mm pvc stormwater pipe to pvc DWV pipe because (DN) 90mm pvc stormwater pipe is the smallest size. Doing this is easy as you only need to buy a 100x90mm stormwater adapter and a 100 x 50mm DWV invert taper. 1. Buy and fit a meshed 90mm overflow outlet. 2. Buy and fit a 90mm pvc stormwater 90 degree M + F elbow. Fit the M end into the meshed outlet's socket. 3. Fit a short 90mm pvc stormwater pipe (sleeve) between the elbow's female end and the stormwater adapter's female end. 4. Fit the invert taper's largest end over the stormwater adapter. 5. Fit a 50mm DWV pipe to the invert taper. Disregard the above advice, Lisa06 has found a simple fitting that I was unaware of. See her next post. The DWV pipe is much stronger than a 90mm pvc stormwater pipe.and it won't have any problems with the flow due to the vertical riser providing head pressure should water in the pipe ever back up. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Much a do about nothing. You can see the fall heading to the actual drains. Stormwater ingress will be minimal and it's far better to have the top sitting flush rather… 12 6414 Thanks for that, the PVC pipe is still about 40cm below ground level and it sticks out of the sand with no end cap or anything on it just open pipe, is this the finished… 2 10661 Hi all I am looking to run a water line under my concrete footpath which is directly next to my home, was seeing if this is possible without cutting the entire section… 0 20519 |