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Description of solution Storage System for Rainwater Based on the Innocentive specification, the prices are calculated based on a currency for € and $: 1,40 $ for 1,00 €. All prices are wholesaling prices or ex factory for medium (500-1.000) pieces lot sizes. I have marked and calculated my top solution. But the conditions in developing countries are very different. So I have described and calculate some alternative solution. It was nor asked for the collection system but I made some thoughts because you cannot be sure that you can design a collection system just with local material. Following the way of the water there will be the steps. So you have to find the best (cheapest) solution for every step.

1.) Collecting the water from the roof (rain gutter) 2.) Down pipe 3.) Pipe from down pipe to reservoir 4.) Filter 5.) Reservoir and frame for stabilization 6.) Water withdrawal 7.) Extreme low cost / foil storage system

Problems around the system:

A) Overflow protection B) Material choice for Reservoir C) Ultraviolet Resistance (UV-Resistance) D) Oxygen supply for stored water E) Quite incoming water / clear outgoing water from surface F) Temperature G) Mosquito and animal protection H) Complete costs incl. transport and local work I) Bigger units and modular systems

Username: InnoCentive Challenge #: 7497318

InnoCentive Challenge Name: Low-cost Rainwater Storage System

Doc. Number: (internal use only)

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1) Collecting the water from the roof Specification: Low cost For 10m² of roof area Length 5m (modular) and opportunity for cutting Why thinking about rain gutter? Not every roof in developing countries has got a rain gutter so it is point of cost. Dimensioning of the rain gutter Minimum diameter: 10m² * 800 l/(1s 10000m²) = 0,8 l/s Following (DIN EN 12056) there will be a minimum diameter of 50mm for nearly 100% storage volume during heavy rainfall. Fixing material: You have to calculate 15% on top for simple fixing material (wire and/or cable straps, some nails, screws…). Solution 1: Iron rain gutter

Iron zincked 2,06 € [ 2,88 $] per meter about 5m are needed => 10,30 € [14,40$]for one roof side Conclusion: good working system but much too expensive. Solution 2: Plastic rain gutter

Plastic (PVC) 1,70 € [2,38 $] per meter about 5m are needed => 8,50 € [11,90$]for one roof side Conclusion: good working system but also too expensive.

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Solution 3: Plastic Profile Standard (semi finished part) used as rain gutter

Plastic (PVC) 50mm x 50mm x 3mm 1,35 € [1,89 $] per meter

about 5m are needed => 6,75 € [9,45$]for one roof side Conclusion: working system but special parts like endings and connector to down pipes have to be designed and to be produced. The reduction of costs in to less. So its better to buy a Plastic rain gutting system. Solution 4: Iron Fence with plastic foil inlay used as rain gutter [Second Best Solution]

Iron fence Mesh size 12,5mm x 12,5 mm (standard) 55,20 € per roll / 25m/roll / 2,5 strips = 0,88 €/m [1,24 $/m] Mesh size 25mm x 50mm (50% cost reduction) because of less material and machine hours. 0,44 €/m [0,62 $/m]

fence with foil inlay

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Plastic foil (0,1mm): 0,001dm x 10dm x 2dm x 1,2 kg/dm3 x 2,5 € per kg => 0,06 € [0,08 $] per meter about 5m are needed => 0,44 € /m mesh

0,06 € /m foil total: 0,50 € /m x 5m = 2,50 € [3,50 $] for one roof side. Conclusion: cheapest system but it will need about 2h more time per roof side for fixing. It could be necessary to repair the foil. Solution 5: cut drainpipe (without holes) [ TOP Solution ]

Diameter 50mm 0,60 € / m and 0,5 h more time to prepare (cutting) the drainpipe. about 5m + 1m are needed => 3,60 € [5,04$]for one roof side (one more meter because of curved endings) Conclusion: good working system less expensive easy to fix and less risk of rapair. Decision: Both systems cut drainpipe and fence with foil inlay are working low cost solutions. If low cost is top you have to take fence with foil, but in the long term run I think the cut drainpipe will be better because of less risk of repair. The low cost systems are not 100% dense. They just have to collect an high amount of rainfall. There is an option without rain gutter see (chapter 7), it is extreme cost reduced but it needs very much working hours, maintenance and a relative high risk of repair and failure.

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2) Down Pipe Specification: Low cost Height: 3m maximum roof to ground (water storage level) Connection between gutter and down pipe: There are several connectors for European and US to buy, but each is at least about 2,00 € [2,80 $] That’s too much just for one connection. So I will describe some “No cost” solutions. Dimensioning down pipe Same diameter [50mm] like gutter Fixing material: You have to calculate 15% on top (same as gutter). Solution 1: Plastic waste water pipe DIN

Plastic Polypropylene 3,87 € [ 5,42 $] per 3 meter Conclusion: good working system but not the cheapest. Solution 2: Drainpipe as down pipe

Plastic Polypropylene 1,80 € [ 2,52 $] per 3 meter

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Conclusion: as good working system as waste Water pipe and just half the price. Fixing drainpipe at gutter (no cost solution): Down pipe and gutter are the same material. You just have to prepare the roof area and to curve the pipe.

delivery condition cut and curved Solution 3: Foil pipe (foil tube) ) [ TOP Solution ]

Principle of fire fighter tube , but just with thin plastic foil (0,1mm).

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Plastic foil (0,1mm): 0,001dm x 10dm x 1dm x 1,2 kg/dm3 x 0,90 € per kg => 0,011 € [0,015 $] per meter. => 0,033 € [0,045 $] per 3 meter. Conclusion: extremely cheap system. There is a risk of repair but if you take PVC you can fix wholes by gluing or just change the tube. If there is a long way to the reservoir on ground level you have to protect the tube with local material. So there could be cases, when it will be cheaper to use a drainpipe. Fixing foil tube at gutter (no cost solution): Cut the end of the tube (30 cm the middle) and make a node upside the gutter.

3. Pipe from down pipe to reservoir Specification: Low cost Distance: 5m from down pipe to reservoir The best is to have no distance between down pipe and reservoir, but sometimes you need a different position for the reservoir. You can use the same solution as for the down pipe. Changing materials between down pipe and ground pipe should be avoided. Plastic waste water pipes and drain pipes can be buried without any problems. If you want to use the foil tube you have to make a protection frame with local material. See below for some solutions:

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=> 0,03 € [0,04 $] per meter. => 0,15 € [0,21 $] per 5 meter. Local working time 15 min/meter Remark: optionally it could be interesting to use a foil pipe for longer distance water transportation because of the extreme low costs. 4) Filter There are several filter systems available. High-Tech Filters with good cleaning results and no maintenance like hydraulic jump filters or filter collectors. But the prices are not acceptable 97,50 € (reseller price) for hydraulic jump filter or 89,00 € for filter collector. Hydraulic Jump Filter (Diameter 100mm)

As water flows over a stone, its surface is smoothed, rounded and the waterflow is substantially changed by the height drop, from a sub-critical to a super-critical flow. At the bottom of the dip, the waterflow changes again to a sub-critical flow in a process now commonly known as hydraulic jump This resulting increase in water power is similar to a

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strong eddy and any impurities are then forced over the next level and washed away downstream.

Filter collector

Filters directly in the down pipe: The construction of the vertically placed fine filter washes out large and small dirt (larger than 0.28 mm). Moss, leaves and insects are automatically removed. There are also various “medium” priced filtration systems

22,02 € [30,82$] 36,48 € [51,02$] 14,22 € [19,91 $] 79,00 € [110,60$] But it is still to expensive. If you want to have a less budget solution you have to accept a minimum of maintenance and you have to use easy standard parts. No filtration will not work, because the waste is collected at the ground of the storage system . Then non oxygen microbes will make the water uneatable.

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To make a real low budget filter with an optimum of filtration quality you have to use as much standard parts as possible. Therefore for the case I used standard waste water pipes and connectors (HT-Rohr DIN). European rainwater systems do not accept any maintenance. But in developing countries the time for getting water is high and a minimum of regular maintenance will o.k. The optimum filtration material will be a nylon tube. It is the same material as for ladies stockings; just cheaper. But of course you can also use real lady stockings, so replacement will be no problem.

Waste water Pipe Fitting and Nylon Stocking Filter

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The best position of the filter is in the down pipe. Both favourite down pipes are flexible (drain pipe and foil tube) so the filter could be removed very easily. The double collar is without rubber rings. Cleaning the nylon filter will be very easy just by removing the double collar. There is filter grid in the top to catch bigger parts. The overflow is just the case of emergency if you forgot to clean the nylon filter. It should not be connected with the central overflow. So you will immediately see if the filter is not working. The prices are as follows (all prices are checked wholesaling prices) The grid have to be manufactured. If you buy more than 20.000 parts a price of 0,15 € per piece is possible. More will be cheaper of course. Pricing of single parts of the filter: 1) Branch 1,59 € 2,23 $ 2) Grid 0,15 € 0,21 $ 3) Double Collar 1,26 € 1,76 $ 4) Rubber Ring 0,30 € 0,42 $ 5) Nylon Filter 0,41 € 0,57 $ 6) Central Pipe 1,74 € 2,44 $ 7) Grid 0,15 € 0,21 $ 8) Reduction 0,78 € 1,09 $ Total 6,48 € 9,07 $ 50% of the cheapest product you can buy but the same quality and amount of water as the high end filters. The assembly time will be about 15 min. It is not difficult so you can do it in the target country to reduce costs. You can save some more money, if you design your own case. Then you can make No. 1,2,3 as one part and No. 6,7,8 as one part. If the number of parts will be o.k. you can reduce the price down to 4,50 € [ 6,30 $] per unit Sand filter Shown at the extreme low cost solution (see chapter 7) I used a sand filter. It is very cheap. You only need a few square meters of foil and a little sand. But it will need maintenance (cleaning the sand several times) and it needs place near by the wall.

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5. Reservoir The classic storage systems for rainwater are plastic tanks. But weight, volume, costs and transportation is not acceptable. See examples below.

Schütz 120 € [168$] 600liter Intewa 260 € [364$] 1100 liter Graf 27 € [38 $] 500 liter Solution 1: Blow out storage system Based on children wading pools you I have designed a reservoir you can blow out. So there will be a minimum of storage room during transportation and a very light design.

200 liter 4,91€ 2.000 liter 16,40 € cover foil 1,70 € blow out storage for rainwater: If you want to use the shown system for rainwater, you will need a higher geometry and some flat areas, where you can make holes for pipes. So a 500 l blow out storage system could have the following design:

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all dimensions [mm]

The calculation of costs will be not easy. I think twice the price of the 200 liter wading pool will be a first realistic mark. So you have pay about 9,82 € [13,75 $] for the reservoir plus cover foil 1,70 € [2,38 $].

Conclusion: it will be a working solution, but there will be high costs for design and testing. Because of the option to repair you have to use PVC. So you have to produce a large quantity to hold the prices. There will be some problems on top which does not exist for leisure use. The live time has to be much longer. For example you have use ultraviolet resistant foils. It will be better to use a multi air chamber system to avoid a complete failure of the system. The price is o.k. but not really cheap.

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Solution 2: Big Bag with foil inlay (TOP one)

For transportation of sand in the building construction industry big bags are very common. You also can transport liquids with big bags, if you have a foil inlay bag. If the number of pieces (1000 and more) is o.k. you can get every dimension you want for the same price. The outside is bright and UV-stabilized.

foil inlay big bag examples for big bags Based on this idea a have designed a rainwater storage big bag. It is a 6-corner (near by circle) with long straps to hold stabilisation pipes. So you can have very light and good for transportation solution. As inlay I took one with just one hole in the top. So the risk of pollution and unwanted animals (insects) is minimised. Overflow and water withdrawal is no problem (see chapter 6 and A)

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The stabilisation pipes are working like a tent.

Big-bag offer (500 liter bag): not glued inside and outside bag; 5.000 pieces 4,05 € [5,67 $] The pricing is for a 4 corner bag with straps on top. There will be no difference if the straps are at the side and if there will be 6 corners, but therefore are real project is needed.

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Stabilisation pipes: Plastic pipe (20mm diameter; 1mm thickness; 1200mm length ):

3,14 x 0,2dm x 0,01dm x 12dm x 1,2 kg/dm³ x 0,90 € per kg = 0,08 € [0,11 $] Connector pipe (18mm diameter; 1mm thickness; 411mm length ): 3,14 x 0,18dm x 0,01dm x 4,11dm x 1,2 kg/dm³ x 0,90 € per kg = 0,03 € [0,04 $] Pricing of single parts “Big-Bag” reservoir:

Price per Unit Units Total 1) Outside Bag 4,05 € 1 piece 4,05 € 5,67 $ 2) Inside Bag incl. 1 piece - - 3) Pipe 1200mm 0,08 € 6 pieces 0,48 € 0,67 $ 4) Pipe 411 mm 0,03 € 6 pieces 0,18 € 0,25 $

Total 4,71 € 6,59 $

Conclusion: it will be a good working solution and my top one, using a proofed system for transportation in the building construction industry. The inlay foil bag is not 100% leak proof just 99,99999%. That depends on the weldseam. But the leaks are not going bigger. It is just like sweating a few drops per day. This is acceptable. There are two options for the positioning of the bag: downside in earth like seen in chapter 7 or on the ground. You can save a little bit of costs (stabilisation pipes) but this is not a real advantage. The real advantage is the cold and lightless storage. But the work to make the whole in hard ground makes it sometimes easier to deposit the reservoir at the surface. If you will put the reservoir inside earth you also have to dig a hole for water withdrawal which needs time and local material.

6. Water Withdrawal You have to make a hole downside the reservoir an to fix a connector at the foil for the tube. At first you think it will be the easiest to fix the connector by gluing or melting. Gluing (only PVC) with local workers you take the risk of leaking. But you have to do it with developed country man power so you have to pay at least 1,00 € [1,40$] for fixing. The second problem is the position of the hole. There will be no chance to change the position.

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glued tube connector The thinner the foil is the bigger the diameter of the flange has to be. The diameter tube can be minimal. There will be time wait a minute to fill up the water so I have taken a diameter of 1/2 “. It will be much more easy to make a hole into the foil and to fasten the connector with screws.

Connector with screws (hose nipple not shown) There are some systems with winding but they will not work with thin foil.

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Valve: there are many valves to open and to close the reservoir. But the cheapest one will be no valve. After the connector will follow a tube of about 1,5 m. If you need water you just put the tube downside and the water will flow. If you do not need water the tube will be fasten upside and the water stops. You can put a little bit of fabric to protect against pollution and insects. Best you take a clear tube so you can see how much water is inside the reservoir from outside (similar to Pitot tube).

“No-valve” system

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Pricing of withdrawal “screw version” :

Price per Unit Units Total 1) Tube Connector 1,20 € 1 piece 1,20 € 1,68 $ 2) Tube Sheetl 0,20 € 1 piece 0,20 € 0,28 $ 3) Rubber Seal 0,09 € 1 piece 0,09 € 0,13 $ 4) Screw 0,02 € 4 pieces 0,08 € 0,11 $ 5) Tube ½” 0,63 € / m 1,5 m 0,95 € 1,33 $ 6) Hose Clip 0,16 € 1 piece 0,16 € 0,22 $

Total 2,68 € 3,75 $ With glued connectors you can save 0,37 € [0,52 $] of material but you have to solve the problem of local gluing. So I have calculated the saver solution.

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7.) Extreme low cost / foil storage system

If there is enough place around the building, not extremely hard ground, you can store and filter (with no extra costs). You just have to make a double fosse along the roof.

The prices are as follows (all prices are checked wholesaling prices). The thickness of the foil has a main influence of the costs. If you check the ground for sharp pieces before

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fitting the foil it will be possible to take 0,25 mm foil. Because of the option to repair I would prefer PVC foil.

Example for PVC-foil for garden ponds. Price for 0,5 mm incl. tax and no reseller discount.

� Without tax and incl. wholesale for 0,2mm: Plastic foil (0,25mm):

0,0025dm x 10dm x 10dm x 1,2 kg/dm3 x 0,90 € per kg = 0,28 €/m² [0,39 €/m²]

Pricing of single parts of the foil storage system:

Total Total Price per Unit Units Storage Filtration 1) Reservoir Foil per m² 0,28 € 2,4m x 6m= 14,4m² 3,23 € 0,65 € 2) Sand Bed local material - - 3) Plank local material like bamboo or boughs - - 4) Cover Foil [0,12mm] per m²: 0,14 € 1,5m x 6m= 9,0m² 1,26 € - 5) Overflow with fence 0,41 € + 0,15€ 3 pieces - 1,68 € 6) Straw local material - -

Total 4,49 € 2,33 €

There is no special training necessary so. So you just need 2 x 8 h of your own local work to fix the whole system. Resumee: It is not much cheaper than the “Big Bag” solution, but it has got an extremely low cost filtration system and it needs no rain gutter. If you have a hard ground or not enough space in front of the house it will be difficult to realize this solution.

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A) Overflow Protection

The cheapest way for overflow protection is no overflow protection. You just make a dent at the top of the storage system and let the water flow. If it is wanted you can make a small channel to give the water a defined direction [similar to ground pipe]. But you will have a muddy area. With a minimum of costs you can make a connector for overflow if foil is used for storage. Just make a smaller hole than the tube and press and fix it with a hose clip. I have used this system downside 2m deep 24h under water for 10 years without any leaking. But you have to make several tests with the diameters and the material so this solution is for local workers only acceptable as overflow protection.

fixing overflow protection

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Pricing of overflow protection:

Price per Unit Units Total 5) Tube 1½” 1,02 € / m 0,15 m 0,15 € 0,21 $ 6) Cable Clip 0,02 € 1 piece 0,02 € 0,02 $

Total 0,17 € 0,23 $

You can add drainpipes of foil tubes at the end. The length depends on the local situation so you cannot make any pricing. For prices per meter see chapter “ground pipe”.

B) Material choice for reservoir Generally you can use vinyl plastic like polyvinychloride (PVC) or vinyl free plastic like Polyethylen (PE). The price is in the long term run is a little bit better for PVC. Recycling is easier for PE, but it is much more difficult to repair PE for not qualified workers. So if there will be a risk of failure or leaking I would prefer PVC. If there is no risk of failure would prefer PE.

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For the calculation for easy part like foils I have taken the commodity price multiplied with the factor 2,0 . this means for PVC 0,90 € / kg and for PE 1,10 € / kg.

C) Ultraviolet Resistance (UV-Resistance)

For long term use (several years) it will be important that the sunlight will not destroy the storage system. If the storage box is covered with something (straw) it will be no problem. There are some foils with optimised UV-Resistance, but this is no resistance for 100 years. So the extra costs of the better material have to be calculated on top. A solution could be coating the foil but it has to be a very low budget paint. You can use a bitumen paint. There will be good connection between foil and paint. But you have to be careful that there will be no paint inside the water because of the pollution and bitumen colour need a very long drytime. So the best will be to cover the foil with earth and straw or other local material. Only in the case of emergency you can use a bitumen colouring.

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D) Oxygen supply for stored water

There has to be a permanent exchange of air at the surface of the water. Otherwise there will grow anaerobe microbes which are smelling bad. During short time they will makes the water uneatable. In tropic areas this effect could be faster than wanted. So you have to guarantee a circulation of air around the surface of the water.

Solar ventilation: You will need two openings for air conditioning In and out. To guarantee moving air you will usually use an electrical van. In our case this will be much to expensive. So I will use the effect, that warm air is going up. Ingoing Air will come from the overflow opening and the outgoing air will end into a black tube like a smoke pipe. Because of the black colour the air is getting hot and going upside. The hot air is made outside the reservoir so temperature will not be a problem.

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Costs of solar ventilation:

Price per Unit Units Total 1) Black Drain Tube 0,25 € / m 1,5 m 0,38 € 0,53 $ 2) Hose Clip ½” 0,16 € 1 piece 0,16 € 0,22 $

Total 0,44 € 0,75 $ Resumee: Because of the minimum of costs you should ad the solar ventilation to enlarge the storage time.

E) Quite incoming water / clear outgoing water from surface

If there is only a open pipe for the incoming water there will be much turbulence in the storage and small pollution on the ground of the reservoir in moving around drops down the quality of the water. To avoid this effect put one meter of foil pipe (chapter “ground pipes”) at the end of the incoming pipe and fix it with a hose clip. So the water is running through the foil pipe and slowed down and the turbulence is minimized. The best quality of water is a few cm down from surface. To get this water by withdrawal you substitute the one ending connecter by an double ending connector and a thin flexible tube of 1m inside the reservoir. At the end of the tube you fix a small block of Styrofoam so the end of the tube will swim near the surface. Costs of incoming and outgoing water optimising:

Price per Unit Units Total

1) Flexible Tube 0,46 € / m 1,0 m 0,46 € 0,64 $ 2) Hose Clip ½” 0,16 € 1 piece 0,16 € 0,22 $ 3) Styrofoam 0,02 € 1 piece 0,02 € 0,02 $ 4) Cable Clip 1½” 0,02 € 1 piece 0,02 € 0,028 $ 5) Foil Tube 0,011 € / m 1 ,0 m 0,011 € 0,015 $

Total 0,67 € 0,94 $

Resume: You should invest this money to get a better quality of water. The budget 20$ is still o.k.

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F)Temperature

The colder the water will be the longer it will stay eatable. So the best storage is in earth an on top covered with e.g. straw for isolation. If there is no opportunity to store the water downside you have to chose a bright surface a shadowed place for the storage. It could be a problem if a UV-protection colouring is done because it will be in black because of costs. So you have to use a very thin white foil on top which has to be changed when destroyed by sunlight. Another opportunity the isolate the water is also using straw for upside reservoirs. You can use bales of straw or you can use a thin cover bag (about 1,5 € [2,1$] ) around the storage big bag or blow out storage and fill it with straw. So you can reduce the warming of the water during the daytime.

G) Mosquito and animal protection

Because of the “aircondition” it you are forced to have at least two openings for air. Generally animals could come inside the reservoir through the openings. But it is easy to make this openings “animal save” just by taping a rest of the nylon filter material in front of the air tubes.

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H) Complete costs incl. transport and local work

There was a limit of 20$ for basic storage system: The calculation of my favourite (not cheapest) solution “big bag stand alone at ground” is shown below:

1) Reservoir 4,71 € 6,59 $ 2) Water withdrawal 2,68 € 3,75 $ 3) Overflow protection 0,17 € 0,23 $ 4*) Quite incoming outgoing from surface 0,67 € (0,94 $) 5*) Solar Ventilation 0,44 € (0,75 $) Total I 8,76 € 12,26 $ 6) Local Work (5h with minimum skilled worker) 0,89 € 1,25 $ 7) 20% for extra parts 1,75 € 2,45 $ (I think it will be less, because of detailed calculated solution) 8) Transportation (10 kg ) volume minimal 0,06 $ t km * 3.000 km * 0,01 t = 1,28 € 1,80 $ 3000 km because of special plastic parts

Total II 12,68 € 17,76 $

*) not necessary but very useful and calculated

Added systems and parts: A) Filtration 4,50 € 6,30 $ B) water collection and piping see first chapters

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I) Bigger units and modular systems

500 liter is a very small unit for water storage connecting such small units via pipes and tubes will not be the optimal way. I think you should design a larger unit about 2.000 liter (European common size for restroom use) . The cost will be less than double from the 500 liter and you will have four times more volume. If you are looking for larger than 2.000 liter units you can connect two ore more 2.000 liter units with pipes and tubes.

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