Browse Forums Eco Living 1 Nov 18, 2013 9:04 am We are based in QLD, just outside of Brisbane. When the contract for our house build was put together and signed it was a requirement to have a rainwater tank, by the time the build started the rainwater tank requirement was repealed. We opted to leave the rainwater tank in as part of the build including the connection to internal plumbing. Our thinking was the rebate wouldn't be the "real cost." Our tank is 5000ltrs, (should be bigger, but it is all we can afford at the moment.) we plan to add a larger tank at later date. Tank was on its side one day, 24 hours later it was installed and connected. Then we had some rain, thunder storms, heavy rains and more storms Now it looks like this Now I was expecting the tank to be installed on either concrete or a bed of gravel within a boxed wooden frame to stop the gravel from collapsing. I'm very annoyed a out this install. Are my expectation re the tank bedding unrealistic? The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 2Nov 18, 2013 11:45 am Was there anything in your plans? On our plans say its on a concrete base (along with A/c). Otherwise maybe check with council and see what the requirements are for the base. http://camdenbuild.blogspot.com.au/ by invite only please pm me Re: Rainwater tank bedding 3Nov 18, 2013 5:19 pm Hi Robbie55, thanks for replying. The tanks on the plans but no mention of what the tank would be places on. I've checked the tank manufactures installation notes and this install set up not the recommended. We are at Practical completion inspection stage this week so I will go over it with the builder. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 4Nov 18, 2013 5:50 pm Most builder's plans will show a concrete base but poly tanks are not required to have them. You should at least have a compacted sand base that is set below soil level to prevent erosion. There are several issues with the installation but a lot comes back to knowledge and best practice. Most installers and plumbers only do what the regulations allow them to get away with. 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 tank bedding 5Nov 19, 2013 7:12 am Hi SaveH20 thanks for your reply. There is no sand base. Picture of tank on it's side is the same day the bobcat was on site cleaning up. I turned up next day and the tank was up and installed. It's a pile of gravel flattened out and tank placed in top and installed. A combination of freshly turned soil, gravel patted down with the back of a spade and heavy rain and it would be obvious errosion will occur.
I have to confess I haven't seen a setup like ours anywhere. That's for the base and the connection. Saveh20 - I am interested in reading your points relating to this install. This weekend we are going over this house/tank with a fine tooth comb. I have one shot to get this fixed and/or at least plan for future water harvesting plans/set up. Our build is a custom design and this tank looks like a 1/2 @rse install. Pretty doesn't mean it's installed right, either, but I'm wondering in what world did they think I would be ok with this? Re: Rainwater tank bedding 6Nov 19, 2013 12:37 pm There are facets of the installation that make it sub standard to my standards. Unfortunately, a sub standard install is still most often compliant in many examples. It comes back to the knowledge and ethics of the installer. A compacted sand base is mixed with cement and it sets like concrete. I would arm myself with a knowledge of the tank manufacturer's installation instructions and warranty conditions. Also measure some of the bits of gravel as many manufacturers warn not to sit tanks on gravel/stones over a certain size and doing so will void most warranties. Regulations are practically non existent unless pertaining to tank stands, distances from the boundary etc. You might come across some plumbing handbooks that appear to be regulatory but they have no legal standing. Your best chance is arguing that the tank's base as provided does not satisfy the terms and conditions of the manufacturer's warranty. The tank has a submersible pump and I would also check to make sure that they haven't placed the pump directly on the tank's floor. Most pump manufacturers require the pump to be fitted above the sediment layer and not doing this will void most warranties. It also results in the pump vacuuming the floor of sediment which in turn will foul filters. Try and find out the make and model of the pump. They have also plumbed the pump with copper pipe. I would not use copper pipe with rainwater as rainwater is naturally acidic but there are no regulations that prevent installer doing this. Again, it comes back to basic knowledge. There are however regulations that (broadly) address the maximum temperature that cold water can be delivered and your copper pipe is exposed to the QLD sun! AS/NZS 3500.1:2003 SECTION 2.4.1(d) states that cold water pipes and fittings shall be protected from ambient heat. This standard unfortunately is ambiguous as it does not state a maximum temperature but your copper pipe is not protected. As such, it is not compliant as is in my opinion. There is a standard that states that drinking water shall not have a temperature in excess of 40 degrees C. Unfortunately, the pipe also creates a rather ugly archway between the tank and the house but regulations don't prevent this. For obvious reasons, I would not have the harvested water entering the tank through a top inlet that is almost above a submersible pump. At the very least, I would use a calming inlet inside the tank fitted to the end of the infeed pipe. This not only doesn't stir up the sediment layer, it also oxygenates the anaerobic zone. Unfortunately, once again you cannot prevent bad design. You also have a (compliant) dreaded wet system; do you know how many downpipes are harvested? The problem with wet systems is that they have a vertical riser and vertical risers need a lot of velocity to flush detritus from the buried pipe. The wet system as installed is compliant but it is still the pits as it will retain debris. To rectify this and ensure that the underground wet system pipe is regularly flushed, you simply branch a smaller pipe (generally 40 mm) off the bottom of the vertical riser and plumb it via a flexible UV stabilised pond hose to a 40 mm inlet fitted approximately 100 mm above the bottom of the tank and within 75 degrees of the pump's draw outlet. This also oxygenates the anaerobic zone. You have a decent amount of land; I would not have sited the tank in its current location unless it was absolutely necessary. Was it your decision to site it there? I am assuming that you intend having a high fence. EDIT: The reference to "and within 75 degrees of the pump's draw outlet" pertains to tanks that supply water to an external pump. For this installation, having an external pump would have avoided having the (unlagged) copper pipe archway. 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 tank bedding 7Nov 19, 2013 2:56 pm Thank you SaveH2O for taking the time to reply. Many of your comments aligns with alot of my thoughts at the moment. I have also replied to some points in your response, not neccessarily in order. Quote: You have a decent amount of land; I would not have sited the tank in its current location unless it was absolutely necessary. Was it your decision to site it there? I am assuming that you intend having a high fence. If you popped over to my thread and looked at the site plan to determine the location of the tank, we have since the plans were printed requested that the tank be located to the other side, so it is now outside the laundry. OH requested this and it seemed to be more practical to me, closer to laundry and two toilets. Quote: I would arm myself with a knowledge of the tank manufacturer's installation instructions and warranty conditions. Also measure some of the bits of gravel as many manufacturers warn not to sit tanks on gravel/stones over a certain size and doing so will void most warranties. Agree, I have their installation and warranty conditions, in my hot little hands. I will also look at the gravel on site. Quote: The tank has a submersible pump and I would also check to make sure that they haven't placed the pump directly on the tank's floor. Most pump manufacturers require the pump to be fitted above the sediment layer and not doing this will void most warranties. It also results in the pump vacuuming the floor of sediment which in turn will foul filters. Try and find out the make and model of the pump. With FIL in tow we will be looking inside the tank this weekend. I am in the process of finding out more about the pump make and model. I like to know what we have paid for..... Quote: You also have a (compliant) dreaded wet system; do you know how many downpipes are harvested? Four down pipes are connected and are collecting from a roof area of 25 mtrs by 6 mtrs approx.) Quote: To rectify this and ensure that the underground wet system pipe is regularly flushed, you simply branch a smaller pipe (generally 40 mm) off the bottom of the vertical riser and plumb it via a flexible UV stabilised pond hose to a 40 mm inlet fitted approximately 100 mm above the bottom of the tank and within 75 degrees of the pump's draw outlet. This also oxygenates the anaerobic zone. I will look into this as it makes complete sense to me to flush the underground pipes. I shudder at the thought of the quality of the water in the underground pipes after weeks of no rain. Quote: They have also plumbed the pump with copper pipe.......... Unfortunately, the pipe also creates a rather ugly archway between the tank and the house but regulations don't prevent this. Yes indeed they have used copper pipe and yes indeed it is ugly. The tanks is full and I would like to see how it copes when we have heavy rains. Yesterday we had such a storm (unfortunately I could not be at site) and today I note we have a drip. This will keep the dog happy as the ground will stay damp and keep it cool in the middle of summer. Perfect for a dog den, under the copper archway and located between house and tank. Seriously this will need to be fixed. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 8Nov 19, 2013 5:11 pm There would be no hydraulic pressure whatsoever on the dripping seal. Tank movement? Do you know what the overflow pipe size is? kiakhan Four down pipes are connected and are collecting from a roof area of 25 mtrs by 6 mtrs approx.) The tanks is full and I would like to see how it copes when we have heavy rains. QLD rainwater tank installations are notorious for over topping during heavy rain. Your eaves gutter drainage must be compliant to not overflow during a 1:20 Average Recurrence Interval (ARI). The gutter's cross sectional area, the downpipe size and the maximum roof area harvested by each downpipe is calculated by a formula based on the area's 1:20 ARI. The ARI is stated as mm per hour but it is based on an average rainfall intensity over a 5 minute period. The Brisbane 1:20 ARI is 240 mm/hr, based on a 5 minute rainfall intensity with an average of 4 mm/min. 1 mm of water on 1 sq m = 1 litre. You have 4 downpipes harvesting 150 sq m of roof. During a 1:20 ARI, the tank's infeed will be 600 lpm. Regardless of whether the tank's overflow is 90 mm or 100 mm, the tank's overflow pipe has absolutely no hope whatsoever of discharging anywhere near this amount of water. Even the TankVac syphonic overflow system that drains at 9 lps would fall short! Plumbing regulations are very poor when it comes to water tank overflow pipes (and many other things). The Brisbane City Council had (during the compulsory water tank period) a mandate that the tank must harvest a minimum 100 sq m or 50% of the roof area, which ever was the greater. No thought was given to the fact that the tank's overflow needs to be equal to or greater than the tank's inflow capacity when the tank is full. You would have noticed an above ground cap on the tank's infeed pipe. This is an inspection outlet (IO) that I am sure is a mandatory fitting for wet systems in QLD. These supposedly flush out the wet system when the cap is removed but they are far from effective as little water is drained when most of the water is 1/2 a metre lower down. I'm sure (detect sarcasm here) that there would be an 'adequate' flow velocity through the pipes to flush out the wet system during a major storm and I'm also sure that I would not like to be in the line of fire of the infeed pipe's outlet above the tank's top meshed inlet during a downpour when water was blasting out at 10 lps. 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 tank bedding 9Nov 20, 2013 9:28 am Ha! Having already lived in a house where the above occurred (cast your mind back to Brisbane Jan 2011 and the floods - we weren't flooded, but the days and days of endless rain and then a massive storm and heavy rain. Admittedly even the council had trouble.) So I know exactly what you mean. We stood in our raincoats and watched all the water flow out the top of the tank and over the side of the tank. Not much else could be done at that point, except to make sure anything inside the house was ok. In this particular instance the out feed pipe was "supposedly" connected to the storm water system, but this was not the case........ Because crushed or non-existent underground stormwater pipes on the one side (drive access to back of property and shed) do not work !! for previous homeowner. I'm just about to discuss rainwater tank with builder...... Quote: You would have noticed an above ground cap on the tank's infeed pipe. This is an inspection outlet (IO) that I am sure is a mandatory fitting for wet systems in QLD. These supposedly flush out the wet system when the cap is removed but they are far from effective as little water is drained when most of the water is 1/2 a metre lower down. I believe this is the Inspection outlet you referred to above. SaveH2O thank you so much for your responses. I really do appreciate your input. I will post an update after my discussion with the builder. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 10Nov 25, 2013 6:47 am Ok update on tank, so before I met with the builder he had the plumber back to work on the tank and storm water system. He happened to be on site last Monday when we had a storm, hail and heavy rains. Tank over flowed from top and via overflow. So plumber was back for two days working on tank. As a side our storm water exits to the kerbside and then into council storm water system. However during construction the pipe has been crushed 1/2 meter before the pipe connects to the kerb. So this will need to be fix. This also explains the very soft ground and vigorous grow of the grass/weeds. Also tank bedding has been discussed and I am awaiting a reply.. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 11Nov 26, 2013 10:41 am Yeah not so happy with reply something about the bedding been inline with manufactures requirement. Which it isn't. Also queried where the storm water was exiting and turns out exit point for storm water hasn't been finalized....... Just sent rebuttal re bedding. I don't think they will completely fix...... The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 12Nov 26, 2013 10:55 am If all else fails I would highly recommend boxing up the base and mixing up a small pad of concrete yourself. I have two large tanks at 10K litres each. I went beyond the min spec and design a slab myself costing about $500 at the time. However the tanks have been there five years and havent moved a bit. Compare this to my neighbour who did the sand base and his tanks have moved around to the point where he believes it is to late to put on concrete as the tank base is no longer flat and it may be damaged if it goes back onto a flat surface. In your case I would be also suggesting that the slab is tied into the house slab with 10mm steel dowels. Re: Rainwater tank bedding 13Nov 26, 2013 5:42 pm Thanks B-Star. I think I will do just that. I am getting other concreting work done so will look at adding this as well. I am also seriously considering bumping up our "to do" list two larger rainwater tanks (2x 10,000 ltrs). So this will be a project for 2014. I kick myself over this one for not been across it as much as the house and for not been as vigilant when the house plan was drafted to ensure it was on the plan. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 14Nov 26, 2013 8:14 pm Resiting the tank on a slab involves a lot more than just making a slab, there are also disconnections and re-connections and you will not have the same levels. 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 tank bedding 15Dec 02, 2013 2:23 pm Builder is going to redo tank bedding. Going with draining and removing the tank, digging out soil (depth of 100mm) boxing it and back filling with sand/gravel cement mix. Replacing the tank and all connections. If I had time I would have a concretor out there now, but these things take time.... On a side note, the down pipes are 900 and the underground system is 1000 and all other pipes are infeed and outfeed are 1000. I have made two changes to the overflow, something to do with the a collar and one of the pipes. I meant to take pictures today... But forgot. The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 16Dec 02, 2013 2:53 pm kiakhan the down pipes are 900 and the underground system is 1000 and all other pipes are infeed and outfeed are 1000. They will be 90 mm & 100 mm. You need to read my posts again. You are either missing a lot or you have chosen to ignore professional advice. 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 tank bedding 17Dec 02, 2013 6:05 pm Yes you are correct 90 mm & 100 mm. SaveH2O or you have chosen to ignore professional advice. Wow that's a leap. I have read your post and will reread it after I've finished meeting builders, plumbers, carpet layers, pest control, window tinting, blinds, concreter, fencers and the list goes on.... Honestly Saveh20 math was never my strong point. Also the water on this roof can only flow one way. High point is 5100 to 3200 with a concave roof. I paid professionals to do this right and like most people have put my trust in them doing the right thing. I'm hardly going to ignore the advise of professional with one of the biggest financial investments of my life. Cheers The build - https://forum.homeone.com.au/viewtopic.php?f=31&t=67554 The Yard - viewtopic.php?f=19&t=67695 Re: Rainwater tank bedding 18Dec 06, 2013 12:11 pm kiakhan I paid professionals to do this right and like most people have put my trust in them doing the right thing. I'm hardly going to ignore the advise of professional with one of the biggest financial investments of my life. Hi kiakhan, It is your choice as to whether you follow the 'professional' advice of those that you have put your trust in (and who have let you down) or whether you research the advice given to you by others to verify its authenticity to ensure that the work done is compliant and/or is of a high standard. When I give advice on these forums, it is in the knowledge that many others read the threads and there is every chance that more than one person will benefit from my time and effort. I have the strong feeling that you are not following up on all of the advice that I have given and simply concentrating on aesthetics. This is frustrating as it not only wastes my time, it could/will inadvertently disadvantage others. Amongst other issues that I have alerted you to, I have gone to lengths to explain the amount of water that will be draining off the 150 sq m roof harvest area supplying the tank during a (near to) Brisbane area's 1:20 ARI. Your 150 sq m roof area drained is also subjected to a multiplier that factors wind driven rain. If your roof slope is let's say 23 degrees, the multiplier is 1.21. In other words, the roof area would be factored as 150 sq m x 1.21 = 181.5 sq m. If your area's 1:20 ARI is 240 mm hr (based on a 5 minute average rainfall intensity of 4 mm/min), the roof area would be factored to drain 181.5 (sq m) x 4 (mm/min) = 726 litres per minute during wind driven rain for roof drainage compliance that determines the required gutter cross sectional area and the number and size of the downpipes. Stormwater retention system regulations are poor at best and the BCC has in the past shown a woeful lack of understanding of hydraulics as per their failure to recognise water tank overflow pipe hydraulic capacity limitations. Regardless of this, a good ('professional') plumber will design all facets of a rainwater retention system so that it is compliant with the National Plumbing and Drainage Code and is not sub standard. Unfortunately, this is not always done and a casual stroll through the many threads and blogs on this site will show numerous examples of sub standard and excessively priced installs that are nevertheless often still compliant. It was stated in an earlier post that the 150 sq m roof area drains through four 90 mm downpipes to a 100 mm pipe. I previously referred to AS2200 on November 26th. I deleted this on December 4th after the post was not acknowledged. AS2200 is the standard that mandates the maximum flow rate through drain pipes laid with a 1:100 fall. For the benefit of all, I offer the following... AS/NZS 3500.3:2003 SECTION 5 - Surface Drainage Systems Design references AS2200 and Figure 5.1 shows that the maximum flow rate for a DN 100 mm pipe laid at 1:100 is 460 litres per minute. Regardless of any deficiencies in other regulations, your 150 sq m roof area would be factored by regulation to drain 726 litres per minute during a 240 mm/hr 1:20 ARI and hydraulic calculations need to ensure that the correct pipe size is used for compliance. The link below is from the QLD Government: Department Of Local Government And Planning that also addresses the above issue. The example used is for a 150 sq m roof in Brisbane. Note that the Brisbane 1:20 ARI is 250 mm/hr. Also note the calculation for the gutter size and the size and number of downpipes required for compliance. http://www.dsdip.qld.gov.au/resources/n ... er/136.pdf EDIT: The 125 mm x 85 mm rectangular gutter size used as the example in the QLD Government document linked above is stated to have a cross sectional area of approximately 8,000 sq mm. 125 x 85 = 10,625. The reason that the gutter's cross sectional area is the lesser figure (approximately 8,000 sq mm) is because the measure is taken from 10 mm below the lowest wall (which is usually the back wall) or 10 mm below the gutter overflow slots if optioned. 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 tank bedding 19Jan 02, 2014 11:15 am A couple of years back on our old house, we added a 10 000 litre poly water tank, and the instructions for the base was that if you didn't have a concrete base, you could use crusher dust mixed with cement power. That tank water put in place on the crusher dust about 20cm above existing ground level, and whilst small bits of the crusher dust got washed away in the next dumping rain, the rest of it is as it was when I installed it. FWIW, it was attached to a 2 car garage (7 x 6m) and glad I didn't get a smaller tank. Also the downpipes go straight to the tank in the air, and not down underground then back up again. I might add that this is in the Logan City area of Queensland. Owner Building at Jimboomba Woods in Logan City Qld. Blog : http://bandlnewhomebuild.blogspot.com H1 thread : viewtopic.php?f=38&t=68283 . Hi All! I have engaged a plumber to re-do the stormwater drainage system on my property which is mid-70s and had blocked/cracked clay pipe drains. The works has… 0 18686 18 90427 DIY, Home Maintenance & Repair But if it is a ground level open pit, then it is not a charged system. No surprises there. The pipes have obviously been altered and there would be a reason for this.… 3 31266 |