Browse Forums Eco Living Re: Sludge in rain water tank 3Jun 22, 2015 3:22 pm 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: Sludge in rain water tank 4Jun 22, 2015 4:55 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Sludge in rain water tank 5Jun 22, 2015 7:31 pm 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: Sludge in rain water tank 6Jun 22, 2015 8:01 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Sludge in rain water tank 9Jul 01, 2015 10:31 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Sludge in rain water tank 11Jul 06, 2015 11:41 pm 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: Sludge in rain water tank 13Jul 09, 2015 11:56 pm 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: Sludge in rain water tank 15Jul 11, 2015 6:36 pm 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: Sludge in rain water tank 16Jul 13, 2015 1:40 pm Thanks for your further info, H2O. I have some more questions: Stewie, I’m puzzled about a couple captions in your diagram: “Anaerobic sludge layer in base of tank to assist water treatment” I don’t understand how the sludge can help improve the water quality (unless it is in a wastewater treatment system). Does it also apply to a rainwater tank to supply drinking water? If it does, how does it help? From reading research papers on what gets into rainwater from roofs, (eg by Mirela Magyar), I have the impression that metallic compounds and other pollutants attach to the sludge, and to maximise water quality, the sludge should be minimised, and water taken from above the sludge layer. “Biofilms on inside of tank assist water treatment and capture microbial contamination” I thought biofilms were layers of bacteria. Is this correct? If so, why would you want them inside your rainwater tank? Even if they inevitably get there, how could they help the water quality (unless it is a wastewater treatment system)? “Bottom of overflow pipe extends into anaerobic zone to remove sludge and sediment off bottom of tank” This sounds like a generic version of a TankVac. If what SaveH2O and people I’ve spoken to recently say is correct, and an outlet at the base of the tank would only remove sludge from a very small radius around the outlet, would a TankVac type of device also only remove sludge from a small radius around itself? Save H2O, you say “The overflow outlet's wire mesh can gum up and when this happens, the tank will over-top.” Would a flap valve instead of a fixed outlet on the overflow be a good idea to prevent it clogging? “you cannot have a low restriction inlet fitted to the first tank (if you have a wet system) because the system would remain flooded if you did.” What’s a low restriction outlet? Would you describe our system (with the only underground pipe connecting the two tanks to a pump) as a wet or dry system? “First flush diverters don't prevent sediment going into the tank” I accept that they wouldn’t stop all sediment going into the tank, but I can’t see how they wouldn’t stop some or even most. We’re thinking of having a system to manually override the first flush diverter (FFD), so that we can keep flushing when the roof is dusty and flush minimally or not at all when there have been frequent rains for long enough to clean the roof. We thought this would improve the performance of the first flush diverters. At the moment our thinking is to have one pipe coming out the side of the FFD with a valve, to keep flushing if we wanted to, and another valve at the top that can be turned off to prevent the water going into the FFD. “I also agree with bashworth's answer re rat tailing.” What’s rat tailing? I also have a question on another angle. At the moment we just have buckets under pops in the gutter (no tanks yet). I’ve been monitoring the water in the buckets every day for appearance and taste. Unless there has just been at least a few millimetres of rain, the water tastes bad. Originally, I assumed the taste was due to the new zinc galvanised roof and gutter (all done in about March 2012), but if it is due to the metal on the roof, I’m surprised that it takes this long to stop affecting the taste. Other things on the roof include 8 PV solar cells and stand; at times lots of dust (from sedimentary soil based mainly on siltstone); a few gumleaves, other leaves, pine needles and twigs; an occasional bit of bird poo. The sometimes bad taste has been consistent when it hasn’t rained for a day or so, and then there is a small rain or frost melting. What could be causing the bad taste? (It’s hard to describe the taste, but it doesn’t taste “off” like decaying organic matter.) I’d also be happy to hear from others about their experience with first flush diverters, leaf-diverting rain heads, floating inlets, TankVac-type devices, and any other gadgets, solutions or problems. Re: Sludge in rain water tank 17Jul 13, 2015 6:01 pm einadia Save H2O, you say “The overflow outlet's wire mesh can gum up and when this happens, the tank will over-top.” Would a flap valve instead of a fixed outlet on the overflow be a good idea to prevent it clogging? I have never seen one fitted to an overflow pipe but the manufacturer advertises flap valves as suitable for this purpose. http://rainharvesting.com.au/product/ta ... w-outlets/ einadia What’s a low restriction outlet? No idea. einadia Would you describe our system (with the only underground pipe connecting the two tanks to a pump) as a wet or dry system? Dry. It only refers to the infeed. einadia “First flush diverters don't prevent sediment going into the tank” I accept that they wouldn’t stop all sediment going into the tank, but I can’t see how they wouldn’t stop some or even most. Some, not most. Not all first flush diverters are the same either. Some are better than most. einadia What’s rat tailing? The suctional sphere of influence. einadia I’ve been monitoring the water in the buckets every day for appearance and taste. Unless there has just been at least a few millimetres of rain, the water tastes bad. What could be causing the bad taste? The atmospheric and other pollutants that are washed from the roof when it first rains is called the roof wash or first flush. 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: Sludge in rain water tank 18Jul 14, 2015 1:10 pm Thanks for your answers SaveH2O. It was a low restriction inlet (not outlet) I meant to ask about, re "Having mosquito proof leaf diverters also allows you to fit a low restriction inlet." I've figured out it probably means an inlet with minimal restriction ie fast flow. Is that right? Regarding the underground pipe the plumbers have already put in, we're having second thoughts about it. Our house designer warned us not to have the downpipe going underground before it got to the tank, as he said it would get stagnant water, algae, etc in. When the plumbers proposed an underground pipe connecting the 2 tanks, we told them what the designer said, and they said that wouldn't apply because the water would always be moving, but now we realise that if we have a dry spell and the tanks are nearly empty, we won't be using that pipe, and so the water wouldn't be always moving. Any comments? Also, the pipe is copper, and we suspect the health risks of a copper pipe are worse than that of UPVC or polyethylene. We could possibly have the connecting pipe go along the outside wall of the house (although there's a door in the way). "Not all first flush diverters are the same either. Some are better than most." Which ones are better? We're thinking of getting the Rain Harvesting one, which is the only one we've come across. "The atmospheric and other pollutants that are washed from the roof when it first rains is called the roof wash or first flush." What I'm wondering is which pollutant in particular is giving it the bad taste. I initially assumed it was the zinc from the new roof, but it's over 2 years old now. I suppose I could test to see if it's the dust by mixing up some dust from somewhere not on the roof, letting it settle, and tasting the water. The Your Home Technical Manual (yourhome.gov.au) has a diagram of a rainwater tank system with a “desludging valve” at the bottom. Bashworth and SaveH2O, if what you say is correct, the labelling of this diagram appears to be misleading. Would you agree? Re: Sludge in rain water tank 19Jul 14, 2015 10:57 pm einadia It was a low restriction inlet (not outlet) I meant to ask about, I've figured out it probably means an inlet with minimal restriction ie fast flow. Is that right? Yes. An example of a low restriction outlet would be fitting a flap valve to the overflow outlet to eliminate the outlet's wire mesh which will typically have a 53% open mesh area. Another example would be to fit a larger outlet valve and hose to supply a pump that was some distance from the tank. A wet system low restriction inlet is simply an inlet valve (typically 40mm) that is fitted about 100 mm above the bottom of the tank at the valves lowest point. The valve is connected to a flexible UV stabilised hose (typically Clearpond pondflex) that in turn connects to a same sized DWV pipe. The small DWV pipe then connects to a 100mm DWV tee at the base of the wet system vertical riser via a reduced size fitting, typically a 100mm x 50mm/40mm pipe reducer or a 100mm x 50mm invert taper. http://www.clearpond.com.au/products/al ... ccessories The flow path has priority flow because it operates with more head pressure than the vertical riser because the tank's variable water level will always be lower than the top of the vertical riser. The flow is also higher velocity due to the smaller pipe plus the flow path provides a minimum rise in elevation unlike the vertical riser. There are many advantages to using a low restriction inlet and these were all lessons that we learned through the initial Supadiverta research and development program. It was during this research period that we found that the common rainwater harvesting methods used were very much sub standard. That led to developing the Supadiverta that uses syphonic drainage to divert first stage filtered water through small pipes to a low restriction inlet, i.e., NO vertical riser. It was then realised that the methods used could also be used to significantly improve standard wet systems by improving the water quality, increasing yield and supplementing the wet system's flow rate during heavy rain. einadia Our house designer warned us not to have the downpipe going underground before it got to the tank, as he said it would get stagnant water, algae, etc in. When the plumbers proposed an underground pipe connecting the 2 tanks, we told them what the designer said, and they said that wouldn't apply because the water would always be moving, but now we realise that if we have a dry spell and the tanks are nearly empty, we won't be using that pipe, and so the water wouldn't be always moving. Any comments? Your house designer obviously has knowledge about standard wet systems and he is correct. The water in the pipe should be clean because it comes from the tanks and because both tanks have infeed, the pipe can be small which will generate higher velocity than a large pipe. I wouldn't have any concerns. Are you having any sort of filtration? einadia Also, the pipe is copper, and we suspect the health risks of a copper pipe are worse than that of UPVC or polyethylene. Polyethylene is food grade and inert. uPVC pipe use to contain lead but it no longer does. Not all uPVC stormwater and DWV pipe is certified to AS/NZS 4020, products in contact with drinking water but that is not what the product is designed for. I know of one manufacturer that does certify their uPVC stormwater pipe to AS/NZS4020 but plumbers still issue compliance certificates when they use non AS/NZS 4020 certified uPVC stormwater pipe in rainwater systems even when they know that the water is plumbed for potable use. The regulatory bodies turn a blind eye to the practice. Rainwater is naturally acidic and becoming even more so due to the continuing elevated levels of carbon dioxide (CO2) in the atmosphere. Acidic water reacts with copper and copper piping should never be used with rainwater. You can alter the pH by adding a nylon bag of limestone chips into each tank, just tether a small float to the bag for easy retrieval. Adding bi carbonate of soda also does the trick. Because rainwater lacks minerals, some householders also add Epsom Salts if the water is used for potable purposes. einadia "Not all first flush diverters are the same either. Some are better than most." Which ones are better? You first need to know the roof area diverted to each FFD. Most FFDs use 90mm (OD) uPVC stormwater pipe, the ID is usually 86.2mm. This gives an internal volume of 5.83 litres per metre. 100mm SN6 DWV pipe has an OD of 110mm and an ID of 104mm. This gives an internal volume of 8.5 litres per metre, 46% more than the 90mm uPVC stormwater pipe. If the roof area was let's say 40 sq m (including gutters) plan area, it would only take an insignificant 0.3mm of rain to fill a two metre long 90mm first flush diverter. Using a 100mm pipe and a longer length is better. When most first flush diverters are full, an internal ball rises and seals the top to prevent a venturi effect (supposedly) recycling the flush. Most debris and bird droppings are washed from the roof and gutters during heavy rain, long after the first flush is full but remember the ball seal? It also diverts muck over the top to the tank. FFDs with drippers are responsible for a lot of yield loss. A tap dripping at 1 drop per second (not apothecaries measure) will lose about 13.5 litres per 24 hours but many FFDs flow with a steady stream and this is during the entire rain event and afterwards as the diverter empties. Annual yield losses can be significant. SUMMARY: It is best to use a 100mm pipe of maximum available length and have a manual drain facility rather than a dripper. If you go to JNK40's Gympie thread, you will see a FFD on his garage. The FFD is DIY and made from a tee at the top, a pipe, a 100mm bracket cap with a 19mm outlet spout at the bottom with some 19mm polypipe and an inline tap attached. The amount collected is known and it can be collected. If it was to be drained, a longer poly pipe would be used. A floating ball is not needed because the pipe is deep and the water settles. The photos are also below. See if you can identify several examples of a plumber's lack of knowledge in the photo below. There are 2 vertical risers and 2 FFDs supplied from multiple downpipes. einadia "The atmospheric and other pollutants that are washed from the roof when it first rains is called the roof wash or first flush." What I'm wondering is which pollutant in particular is giving it the bad taste. No idea. You can get water tested if you are really interested but it could be general atmospheric pollutants. Water that has a dissolved oxygen (DO) level less than 1 mg/L is considered anaerobic and is said to taste foul. Maybe bacterial activity breaking down dissolved bird droppings has depleted the DO levels but I wouldn't think that it would be that fast. Maybe the taste comes from the bucket. einadia The Your Home Technical Manual (yourhome.gov.au) has a diagram of a rainwater tank system with a “desludging valve” at the bottom. Bashworth and SaveH2O, if what you say is correct, the labelling of this diagram appears to be misleading. Would you agree? Yes. It shows a misunderstanding as only the immediate zone is cleaned. There are also several mistakes shown in other diagrams and photos but it is easy to find fault in reports and advice by 'experts' in this field. 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: Sludge in rain water tank 20Jul 16, 2015 3:43 pm Thanks again SaveH2O. You asked: “Are you having any sort of filtration?” No, we’re not. You said “I know of one manufacturer that does certify their uPVC stormwater pipe to AS/NZS4020” Which manufacturer? I have the impression that the difference between food grade and non food grade polyethylene is the smoothness of the surface (to minimise bacteria habitat) rather than the chemistry of the plastic. Is that correct? “You can alter the pH by adding a nylon bag of limestone chips into the tank” Where do you get limestone chips? I presume this sets up a chemical reaction which eventually depletes the limestone, which then needs replacing. Is this correct? I wouldn’t like to add sodium bicarbonate – I try to minimise my sodium intake, for health reasons, and also minimise what goes into the soil, as high levels damage plants and soil. “You first need to know the roof area diverted to each FFD.” The total roof area is c. 175 sq m, divided equally between 2 first FFDs, which gives c. 87 sq m per FFD. (This area doesn’t include the gutter – which is half round and 16.8m long.) The roof is at a pitch or about 7 deg. Re water taste, after reading/re-reading a few papers (Magyar et al 2006, 2007, Chapman et al 2006) on what gets into rainwater from roofs, I’m again thinking the taste could be from the zinc on the galv. roof. If so, I wonder how long it will take to go away. I grew up drinking rainwater from a house with a galv. roof (40 years old when I was 15) and I don’t remember this taste. Can a plumber put a tap on a rain water tank which is full? Tank is similar to one in photo. Cheers. 0 1752 If you can calculate the reasonable charged head from let's say 100mm below the gutter to the top of where the vertical riser's horizontal discharge pipe will be, that… 11 17664 Building Standards; Getting It Right! Thank you for the generous offer. I need to get the plumber out to give me an explanation. As mentioned I haven't seen any rain water discharge from pipes 1& 3. It… 7 10986 |