Browse Forums Eco Living 1 Jul 01, 2013 11:18 pm Hi, I have been researching & reading with interest different posts on collection of rainwater. I have a couple of questions I was hoping your knowledgeable members may be able to assist me with? 1. Does the gradient of the pipe runs in a wet system need to be towards the tank or can it fall the opposite direction providing a drain/flush point is provided at the lowest point? 2. Is there a standard for head height in a wet system? Thanks in Advance, David. Re: Rainwater Harvesting Wet System Questions 2Jul 02, 2013 2:03 am Dave07 1. Does the gradient of the pipe runs in a wet system need to be towards the tank or can it fall the opposite direction providing a drain/flush point is provided at the lowest point? COMPLIANCE If the wet system is part of a 'loop' that drains back to the stormwater system via a tank's overflow pipe, it is part of the stormwater drainage system. Stormwater pipes must drain with a minimum 1:100 slope (the wet system vertical riser is overlooked). PRACTICALITY Bed load travels much slower than the water in a charged system due to water travelling in streamlines. Water travels fastest through the core. The problem with a wet system is the retention of debris and the resultant debris build up and anaerobic conditions unless the pipes are regularly flushed. Flushing reduces yield and the term "flushing" is a misnomer as pipes are more drained than flushed. This is due to the limited and quickly diminished available head in the downpipe(s) and riser. This severely impacts on a wet system being able to be properly flushed, particularly when the flush valve is at the end of the pipe opposite the normal direction of flow. The recognised required minimum flushing velocity in stormwater pipe is .6 metres per second. If you are using let's say 100 mm SN6 DWV pipe that has an OD of 110 mm and an ID of 104 mm, it will hold 8.5 litres per metre. To achieve the minimum flushing velocity, the water will need to travel at 8.5 X .6 = 5.1 litres per second or 306 litres per minute! This is why silt builds up all along a wet system pipe. Having the bed load travel up even a slight slope will further slow the bed load. The wet system riser however is VERTICAL and so even if the required minimum flushing velocity for a horizontal drain pipe is achieved, a lot of the debris will not flush to the tank's top meshed inlet. If you have no choice but to run the pipe uphill and have a flush valve away from the tank, then you should consider installing a simple DIY sediment trap in a non turbulent section of pipe between the downpipes and the tank. This will also dramatically improve your water quality. Check out the diagram posted by jnk40 on the 5/11 in the linked thread below. Note that the diagram is discussed in a following post. viewtopic.php?f=35&t=60317&start=40 Fitting a flush valve at a high point will not 'flush' all of the pipe. Dave07 2. Is there a standard for head height in a wet system? The figure 300 mm is often quoted on various websites and this includes those run by various regulatory and plumbing bodies. The fact is that the regulations are very poorly written or non existent and you will not find a 300 mm figure written in any of the primary regulations. If you look at the diagram at the bottom of the Victorian Plumbing Industry Commission technical solution sheet that I have linked below, you will notice that it shows a 300 mm head. The document however is only a guideline and other advice given is also erroneous. Plumbers and many others consider the document to be a regulatory guideline and is one reason why there are so many bad installs by untrained 'professionals'. EDIT BELOW: The VBA keeps changing the Technical Solution Sheet doc number and so I will paste the substantially flawed (and very long lived) diagram instead. Leaf diverter not required in Victoria (but should be mandatory on all wet systems). Inspection openings not required in Victoria and are useless as depicted because they will not effectively flush the 'sump'. 300mm head advice is wrong. Advice on overflow size is manifestly wrong. The overflow capacity must be equal to or greater than the maximum inflow capacity. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ When I design a wet system, I always calculate the flow rate through the pipe as being sufficient to handle a 1:20 Average Recurrence Interval (ARI) plus an allowance for even heavier rain. A 1:20 ARI is the minimum that eaves gutters and downpipes must be able to drain without overflowing. I also calculate the tank's overflow capacity by the same parameters. You may have noticed that the linked PIC document, amongst other misinformation, also shows on the diagram and states in the earlier text that the overflow pipe must be the same size as the stormwater charge pipe. This is wrong as a charged pipe flows full of water, could be supplied by several downpipes and is subject to head pressure whereas the tank overflow has no head pressure and draws an annular vortex. This needs to be realised when designing a wet system as numerous tanks supplied by wet systems overtop during heavy rain when their inflow capacity exceeds the overflow capacity. Very, very few plumbers will be able to tell you the maximum flow rate applicable to the various sizes of water tank overflow pipes yet this knowledge is vital when determining the maximum roof areas that can be drained without risk of the tank overtopping whenever the tank fills during a 1:20 ARI. The first thing you need to do is determine your regions 1:20 ARI and the total roof area that will supply the wet system pipe so you can calculate the 1:20 ARI flow rate to the tank. You then need to determine the intended pipe size and its length. If you don't have a tank, you need to determine the head you will have when feeding to the tank's top inlet at different heights. I have seen many mistakes made when people have measured the head as being from the bottom of the gutter to the tank's inlet mesh prior to ordering the tank. Allowance must be made for head loss at the top of the downpipe resulting from the loss of hydraulic connectivity due to the annular vortex or generated bubbles. You must also measure the head not from the tank's inlet mesh but to the very top of the vertical riser less half that pipe's diameter. You should also use a leaf diverter and this could be mandatory in your area. This will further reduce the available head. The length of the pipe also diminishes the dynamic head and people also often fail to equate the pipe fitting's friction losses as an additional length of pipe. Once you know the parameters you have to work within, you can determine the minimum head requirement. EDITED 27/11/2013 Posted new document link from the Victorian Building Authority that has replaced the Victorian Plumbing Industry Commission. EDITED 03/12/2013 Additional information on tank overflow pipe flow rates. 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: Rainwater Harvesting Wet System Questions 4Jul 03, 2013 12:30 am If you post the area/region you are in, I can let you know your 1:20 ARI. The ARI is based on a rainfall intensity over a 5 minute duration. The roof area harvested by each downpipe is the roof area between the gutter high points (the gutter's slope apex). You will see a gradual difference between the height/gap between the bottom of the gutter and the bottom of the fascia. You will also usually find a join in the gutter at this point. The downpipe is fitted at the gutter's low point. This will give you a good idea of the roof area harvested by each downpipe. From this, you then measure the length of the wet system pipe and if you know the available head, you can work out which pipe size is best or I can do that for you. It is a balancing act with the pipe as using a big pipe means a lower velocity whereas a smaller pipe will have greater velocity but it needs more head. Fitting a supplementary low inlet that branches off the main pipe at the riser's tee will give you an additional infeed that operates with a greater head, the head being measured to the (varying) height of the water in the tank and not to the height of the riser above the tank. This allows a lesser head to be factored, the degree to which depends on the size of the lower inlet used.The low inlet also gives the bed load a low restriction flow path into the tank that substantially aids the pipe flushing, improves the water quality, increases yield and reduces maintenance. The best variant of this method depends on several factors including whether the property is rural or urban, the size of tank, the number of downpipes or roof area diverted, the area's 1:20 ARI and the intended end use of the water harvested but the downpipes must be fitted with good leaf diverters. If you are in suburbia, it is often possible to eliminate the need for an overflow pipe regardless of the number of downpipes harvested as we have developed a harvesting and filtering system that can also substitute for the overflow pipe. If you have a big tank and need to maximise yield, fitting a TankVac overflow system will increase the overflow capacity as well as syphoning water from the tank floor, substantially improving the water quality. 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: Rainwater Harvesting Wet System Questions 5Jul 04, 2013 11:37 pm Hi & thanks again for your advise. We live in the Lewiston/Gawler River area in SA. Proposed tank is a 22500L. A second tank will be installed near out 25' x 50' shed, but that is relatively straight forward. The shed is some distance from the house. Block is reasonably level with slight fall towards front. Would like to plumb to, & run the whole house on rainwater. Link to house plan - http://imageshack.us/photo/my-images/844/ku2f.jpg/ Regards, David. Re: Rainwater Harvesting Wet System Questions 6Jul 05, 2013 4:03 am Hi David, Your (eaves gutter) 1:20 ARI is 120 mm/hr which is measured as a 5 minute intensity of 10 mm of rain in 5 minutes. The house roof harvest area would therefore be about 440 litres /min during a 1:20 ARI. 1 mm of water on 1 sq m = 1 litre. Your annual average rainfall however appears to be about 430 mm. If we factor an 85% yield(which is very good), this equates as 220 sq m X 430 X .85 = 80,410 litres harvested annually. The 50 X 25 sq m (1,250 sq m) shed would harvest approximately 456,000 litres annually or a combined 536,000 litres annually. The above raises the question of what % of water do you anticipate that you will need for household/potable use and what will the rest be used for. Most places collect all of their water as one mass and draw the same water regardless of its end use. If you diverted very clean water to a tank that supplied the house and diverted other water to another obviously much larger tank, then the flow paths would need to accommodate this. The thread below describes a system that does this but that system was also designed around having an excess roof harvest during the QLD wet season. The last diagram is on page 3. Your system should also be designed around the anticipated usage indoors and outdoors for the best results. This is easy to do. viewtopic.php?f=35&t=60317 I am surprised at the location of some of the downpipes and have concerns. I can explain further if needed. Most 22,500 litre tanks are about 3.5 metres in diameter and about 2.5 metres high at the inlet. Do you know what the height of the bottom of the gutter will be? If your gutters are going to be let's say 2.7 metres high, a leaf eater would reduce this by about 400 mm. Even if you got away with a 300 mm head, you would only have an available head of 2 metres. Do you know what the gutter's height will be? Will you also be connected to stormwater? 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: Rainwater Harvesting Wet System Questions 9Jul 05, 2013 8:10 am Thanks SaveH20. Yes, sorry the shed measurements were in feet. The down pipes are where the builder located then 20 years ago apart for the pergola. If you have some suggestions on placement I am interested! From the underside of the gutters to our path is 2320mm but the position of the tank is actually 200mm lower than the path level. I was planning on digging the tank in to maintain a minimum 300mm head. We are in a rural area so stormwater is directed towards the front, well past the front of the house & left to soak in around the trees. Regards, David. Re: Rainwater Harvesting Wet System Questions 10Jul 06, 2013 4:35 pm Danois That would be an aircraft hangar! Thanks Danois, seano & David. I was wondering what the shed would be used for. I completely overlooked the foot symbols. Lucky l'm not a builder! So, the shed's roof area is about 116 sq m ( 1 sq m = 10.76 sq feet). Assuming an average rainfall of 430 mm and a 85% yield, the shed would harvest an additional 116 X 430 X .85 = 42,398 litres per year. This will give a combined total of about 122,800 litres annually or an average of about 336 litres per day. This assumes that the two tanks will be linked. It would be good to use the shed tank as a separate storage/settling tank to top up the house tank when required. It would require 22,500 ÷ 220 X .85 = nearly 87 mm of rain to fill a 22,500 litre tank from the house roof. I have guesstimated the house roof harvest area as 220 sq m. Even if the tank was half full prior to a major rain event, it would still take a lot of rain to fill the tank. I could not find average annual rainfall figures for Lewiston but the nearest weather stations to Lewiston/Gawler River area can be found on the BOM site that I have linked below. http://www.bom.gov.au/climate/data/stations/ The 2.5 m usual inlet height may not apply to the make of tank you are considering and this needs to be checked. A lot of people make head miscalculations when ordering their tanks. I suggest that you use the Leaf Eater Advanced on your wet system. These will not only prevent mosquitoes breeding, the fine outer mesh also diverts solid bird droppings and most other rubbish. It is trapped organic material in wet systems that create anaerobic conditions. Many leaf diverters have a 6-8 mm coarse outer mesh that allows solid bird droppings and other debris to drop through and then wash through the finer inner mesh. Manufacturer have tried to devise leaf diverters with fine outer mesh but steep mesh angles are needed to prevent debris adhering to the mesh. Steep mesh angles increase the diverter's vertical length and this in turn decreases the available head as well as increasing costs, the reason most leaf diverters are made with filter mesh with inferior slopes. So, the total head from the gutter's sole to the ground level at the tank is about 2.5 metres. You need to make an allowance for the height of the water overflowing from the riser above the mesh during a storm and this is usually about 80 mm, depending on the tank's design. The working head at the downpipe then needs factoring. I have linked a simple online flow rate calculator below. This uses the Hazen Williams formula which is very simple. Enter 150 as the PVC roughness coefficient. http://www.calctool.org/CALC/eng/civil/hazen-williams_g HOUSE DIAGRAM: If you denote the downpipe nearest the tank as being downpipe 1 and then sequence the downpipes in a clockwise direction, (and not being able to see the property and know where paths and driveways are), my first impression is to have downpipes 1 & 2 share a common pipe and have downpipes 3, 4, 5 & 6 share a second pipe. The two pipes would connect via a tee near downpipe 1 to drain to the tank. With the tank's location being 200 mm lower, this means that the above pipes would have a downward slope. This leads me to think that you intend using the existing stormwater pipes that slope the opposite way. Usage calculations depends on the number of household residents. If the average 336 lpd (that assumes a high 85% yield) is insufficient to provide year around use, then perhaps do some calculations based on sanitary flushing and laundry use. Sanitary flushing per person is generally averaged as 24 litres per day but this varies depending on the cistern size. There are other things that could also be considered, for example, is there room at the house where a couple of tall narrow based tanks could be sited? This would allow you to harvest 2-3 downpipes to each tank and these tanks could be balanced to each other and to the main tank plus it would also allow you to have a smaller and lower main tank. This would be further advantageous if the house is on stumps. If the existing pipes were used and the piped water was filtered through leaf diverters, then you could also use a supplementary low inlet fitted 100 mm or so above the bottom of the tank. This will provide the bed load with a non restrictive flow path into the tank. The slope to the tank would also be ideal for fitting a sediment trap to the main pipe extension that would have to be plumbed to the vertical riser. 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: Rainwater Harvesting Wet System Questions 11Jul 06, 2013 4:39 pm David, re the downpipes, do you have gutter overflows during heavy rain between downpipes 1 & 2 and particularly downpipes 2 & 3? 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: Rainwater Harvesting Wet System Questions 12Jul 06, 2013 5:22 pm Probably only once a year we have a major, short downpour that results in overflows pretty much all round. On the current storm water pipes, they will not be used & every thing will be redone using 100mm. I had thought of having down pipes 1, 2 & 3 on one run & 4, 5 & 6 around the back on another. Would you suggest I T the runs together as opposed to two risers & inlets? Will definitely go with the leafeaters as recommended & just clean them regularly! I had planned to dig the tank in to end up with a 1730mm inlet height. Thanks, David. Re: Rainwater Harvesting Wet System Questions 13Jul 06, 2013 7:48 pm Gutter overflows. There is a lot of distance between downpipes 1 & 2. The same with downpipes 2 & 3 but those two downpipes also have two corners between them. Are the gutters also slotted? The links below are off one of my websites and they explain why gutters overflow when not blocked. http://www.gutterpumper.com.au/gutters-overflow.html http://www.gutterpumper.com.au/frequent ... tions.html Having downpipes 1 & 2 plumbed separately would use less pipe and trenching than if downpipe 3 was also picked up. You will only need one 100 mm pipe and riser going to the tank. A 300 mm head will be ok if you also use a supplementary low inlet. The larger the inlet, the higher the flow rate through that inlet. A 40 mm inlet would be ideal. A low inlet operates with more head than a riser. You fit a tee at the bottom of the riser and then reduce one of the tee's outlets to fit the pipe that feeds the low inlet. There are several ways to do this and the best way is determined by the flow path and the pipes used. The smaller pipe will have much higher velocity than the riser and will act as a vacuum to transfer the bed load. A word about the 100 mm pipes. Flushing velocity is important and if you use 100 mm solvent weld SN6 rated DWV pipes, they have a volume of 8.53 litres per metre as the SN6 DWV pipe has an internal diameter of 104 mm. Downpipe 2 has a run of approximately 16 metres to downpipe 1 and it would need a doozy of a storm to generate the necessary velocity to flush this section of pipe. It just won't happen! If you use a smaller diameter pipe for that initial run and then increase the pipe size, that section of pipe will flush better while still providing an adequate drainage capacity. The same goes for downpipe 3 to 4. DWV pipes are made in 40, 50, 65, 80, 100 mm and larger sizes. The pipes and fittings can differ greatly in price between retailers and it pays to shop around. The link below gives an indication of the price difference between the pipe sizes. http://www.pipeonline.com.au/listProduc ... E/DWV+PIPE Sizing the pipe depends on the roof area drained to the downpipe and the more common use pipes are usually cheaper. The same goes for fittings. Some smaller pipes and fittings can be dearer than larger pipes and fittings. The link below also gives information about their OD and the wall thickness. http://www.iplex.com.au/iplex.php?page=lib&lib=8&sec=52 If downpipe 2 for example harvested 35 sq m of roof, the 1:20 ARI would produce 70 lpm. Using a 50 mm pipe would provide a suitable drainage safety margin as its internal volume is about 2 litres per metre but the recommended horizontal flushing velocity is .7 metres per second. This is where having a filtering system is also good. A leaf diverter also provides the downpipe with an air gap. This provides an emergency overflow should the drainage not manage for whatever reason. 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: Rainwater Harvesting Wet System Questions 15Jul 07, 2013 2:32 am Rather than use 100 mm pipe the entire length, I would run a 50 mm pipe between 1 & 2 as well as between 3 & 4 and l would upsize the pipes to 100 mm before downpipes 1 & 4. The 100 mm pipe will oversize the system but it will be easier and cheaper than using 65 or 80 mm DWV. I never recommend using the cheaper thin walled PVC stormwater pipe but you can buy the 90 mm with 2.5 mm walls rather than use the thinner 1.9 mm walled pipe. If you can get some, this would make the plumbing very simple as you would use 90 mm pvc downpipe, pipes and fittings. At the end of the pipe's runs, you would use 100 X 90 mm DWV-stormwater adapters to connect both pipes to a 100 mm DWV tee. This tee would run a 100 mm DWV pipe a short distance to a second tee at the tank. The tee would then supply a low inlet and the riser. A 90 mm stormwater pipe will easily service downpipes 3-6 and joining both pipes to a 100 mm DWV pipe allows for a simple connection to a low inlet plus you can buy a flap valve to fit the end of the pipe above the top meshed inlet. The low inlet also ensures that the riser is not always full of water. Water fed through a low inlet also oxygenates the anaerobic zone. Just make sure that the outlet supplying the pump is within 75 degrees of the inlet. On reflection given that you intend using the Leaf Eater Advanced, l think that this would be your best option of the two. 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: Rainwater Harvesting Wet System Questions 16Jul 07, 2013 9:50 am Thanks. I'll do some drawings & see how it looks. Are the placement of the down pipes adequate & i have read that extra drainage would be helpful at the high points? When it comes to filtering is a good twin element system enough or is a UV steriliser an ideal addition? Only ever bothered with a filter before but would rather do it right once! Re: Rainwater Harvesting Wet System Questions 17Jul 07, 2013 4:51 pm Hi David, I don't have anything to do with filters and so I am not the best persons to give advice but I can offer some generalised info. The biggest mistake people make is having the pump's draw outlet fitted very low on the tank. The bottom layers of water are known as the anaerobic zone, the word meaning deprived of oxygen. When organic matter breaks down, oxygen is taken from the water. This is particularly bad when the process occurs in the wet system pipes because there is no air/water interface, unlike the water in the tank that can breathe. If the pump's draw outlet is fitted only 50 mm above the bottom of the tank at its lowest point as many are, then the pump will obviously draw the very worst quality water and vacuum the immediate sediment layer. Even when the water is not for potable use, it is still a bad set up as who wants to wash their clothes in poor quality water or have dirty toilet cisterns. The best quality water is found in the upper layers and it is ok to fit a very low outlet if you have a device like the one I have linked below that draws from the best quality water in the tank. You coulld also have one made up for 1/3 of the cost. http://www.crystalclearwater.com.au/waterboy/ The other thing that you could look at is a TankVac as your wet system will deliver much more water during heavy rain than a 90 mm overflow can handle. The TankVac extracts the worst quality water and sediment from the bottom of the tank rather than the best water from the top. It overflows through an 80 mm DWV pipe at 9 lps after a delayed start that is necessary to initiate the syphonic action. You will need to check as to whether the tank's design is suitable for the system as some current tanks are very poorly designed with little mitigation. http://www.youtube.com/watch?v=e1_B9WITe94 It is a New Zealand invention but the Australian contact (Neale) can be Emailed at: namcpheeplumbing@hotmail.com I am told that an Australian website is coming soon. It is always best to concentrate on delivering good quality water to the tank and if you do this, the filters will have an easy life. Having a settling tank system is a huge benefit. Leaf diverters that don't trap and then allow solid bird droppings to wash through are of more benefit than first flush diverters as they operate throughout the entire rain event. A lot of people have a 10 micron filter plus a carbon filter but an additional UV filter is often used. If you have overhanging trees with a possum population, then a good filtration system is vital as possums host Giardia and Cryptosporidium. These are protozoan parasites that can infect the digestive tract of humans. You could also look at a filtering system for the kitchen only and you also have to consider the effect on water pressure if all of the water is filtered. The Alternative Technology Association (ATA) forums would be a good place to ask for advice on filters. Rainwater is also naturally acidic and this will react with copper pipe. If you put limestone chips in a meshed nylon bag into the tank, this will alter the ph. The chips will build up a protective covering as they disolve and so you will need to take the bag out every 6 months or so and break them again. Just tether a small float to the bag so that you can retrieve it. DOWNPIPES Few houses have well designed roof drainage and display homes are a glaring example. When inspectors were commissioned by the Dept of Fair Trading Review Advisory Committee to randomly inspect display homes during the recent NSW inquiry into high fronted guttering and gutter compliance, of the 35 display homes inspected, only one was found to be compliant! You can access the report on the link I previously posted. Most overflows, unless the gutter is blocked with debris, occur away from the downpipe due to most downpipes being plumbed at the end of the walls for aesthetics, leaving the greater roof area the furthest distance from the downpipes. If you call a plumber, the first thing that they usually say is "you need a bigger downpipe" but that is usually not the solution when the overflow is happening 8-10 metres from the nearest downpipe. The device I linked offers a neat solution at very low cost (usually less than $30 for the items plus all fittings). If you want to try one, I will send you one FOC. Just PM me. You will need a 32 mm metal hole saw. 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: Rainwater Harvesting Wet System Questions 18Jul 08, 2013 12:07 am Once again, thanks SaveH20. So pipework would end up something like this? http://imageshack.us/photo/my-images/443/7mc4.jpg/ Re: Rainwater Harvesting Wet System Questions 19Jul 09, 2013 4:36 am Hi David, I had thought that running downpipes 1 & 2 separate would have used less pipe but the diagram shows a lot of pipe used to harvest downpipes 3-6 whereas I had envisioned a single pipe following the house perimeter. Obviously I can't see the property but if it is more straight forward to run downpipes 1-3 together, then that is what you obviously have to do. I didn't have time yesterday to get a cost comparison on the 2.5 mm walled 90 mm stormwater pipe. The normal 90 mm thin walled pipe is very weak but most plumbers use it for wet systems, mainly because it is cheap and they have no pride in their work. The better plumbers use DWV pipe. If you are on Bay of Biscay, then I wouldn't use the flimsy stuff. Re my earlier suggestion to initially run some 50 mm pipe, the problem is that I don't know the approximate roof areas that downpipes 3 & 4 harvest. There would normally be a high point at the valley near downpipe 4 and if there is, then I wouldn't run a 50 mm pipe between 3 & 2 as downpipe 3 will be harvesting a large roof area. There would most probably also be a high point between downpipes 4 & 6 near the wall separating living 2 & bedroom 2. If there is, then downpipe 4 is also harvesting a fairly large roof area due to the additional pergola roof area. It would be ok if there was more available head but 300 mm head on a long run during a major storm off a decent roof area could overtax a 50 mm pipe. The Gutter Pumpers that you have drawn are fitted at a valley. Valleys attract leaves and they flow down the valley en mass. The Gutter Pumper only generates a vacuum once the water is more than 20 mm deep and this means that a high point along a straight length of gutter is flushed prior to the vacuum starting. It's normal high flow rate also means that it operates with frequent vacuum breaks. When this happens, the suction stops and any debris washes past due to the turbulence during heavy rain. Valleys can be a problem however as debris can often 'raft' down. I recommend that you also fit some gutter guard to these areas. The Fielders Watergate is a good zinc mesh that is easy to DIY and comes in a 8 X 1.25 metre pack that costs about $40. Bunnings have it in their garden section. The long run to downpipe 6 is of no consequence as the G-P head is calculated from the gutter. The ID of 20 mm class 12 pressure pipe is 23.7 mm. You will need this figure for the calculator. Add about 25% to the pipe length as a fittings allowance if you don't know the fitting's friction losses. Do you have slotted gutters? If so, the overflows at the valley could be caused by generated hydraulic jumps during heavy rain causing the slots to 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. Re: Rainwater Harvesting Wet System Questions 20Jul 09, 2013 11:41 am Pretty much no leaves get into our gutter, mainly dirt & dust over summer. No the gutters are not slotted. Gutterpumpers preferably in the high spot mid way between runs? I will investigate availability of thick walled 90mm stormwater & see if decent fittings are available. Most I've seen are just as thin as the pipe these days! There is a whole lot more to know than just the answers you seek but they are a good start. Overflow outlets have a mosquito proof mesh. These… 3 9146 Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 20438 Grate, thank you! RexChan if thats the reason i could sleep well without thinking about additional cost. But 1st i'll need to read about NRV cleaning/replaing stuff. I… 7 31919 |