FAQ – Frequently Asked Questions

  1. What is rainwater harvesting?
  2. “Conscious collection and storage of rainwater to cater demands of water, for drinking, irrigation, industrial / commercial and domestic purpose is termed as Rainwater Harvesting”.

  3. Why harvest rainwater? What are the features of rainwater?
  4. The benefits of rainwater harvesting at your home go far beyond your property. Utilizing rainwater reduces the energy and chemicals needed to sanitize and pump water, limits the need to draw from groundwater sources, and retains water in the watershed in which it fell. Rainwater harvesting also halts the negative effects storm water can bring, such as erosion, water temperature fluctuations in streams, and pollution. Rainwater harvesting is a key component of sustainable living.

    Features of Rainwater:

    • Rain water is free of minerals, contaminants, anaerobic bacteria’s.
    • Self Depended. That means does not need to depend water from other sources during dry periods.
    • Decentralized Rainwater collection reduces fast water runoff and can be used for ground water table maintenance by water infiltration.
    • Ability of collecting rain makes independent from weather extremes and cause reduction of flooding.
    • Effects rise in ground water levels.
    • Saves water for our future.
    • At least the dry period’s needs of water can be satisfied by the FILTERED HARVESTED RAINWATER.


  5. What is the aim and motivation of the ACT-WISY Rainwater Harvesting Systems?
  6. Rainwater is the only freshest available water on earth surface. For challenging the water scarce related issues, the only way is to conserve the water at its best.
    ACT-WISY Rainwater Harvesting Systems aims to “Harvest, Store and Use the freshest rainwater through the best and proper way”.

  7. How much water is saved?
  8. This depends on the size of your catchment area (usually the roof of the building) and the amount of rainfall in your area. Typically, domestic systems will reduce mains-water consumption by up to 50%, rising to more than 80% in commercial applications.


  9. Give an example calculation of amount of rainwater harvested?
  10. The total amount of water harvested depends upon the roof catchment area and the average annual rainfall in that region.

    For example: For 100 SQM catchment area with average annual rainfall of 2000 mm has the following calculation:

    Total Amount of Water Harvested = Area of Catchment x Average Annual Rainfall x Coefficient of Transportation x Coefficient of Filtration

    Total Amount of Rainwater Harvested = 100 x 2000 x 0.90 x 0.85 = 1, 53,000 Ltrs per Year.

  11. Is only roof like catchment area is preferred for harvesting rainwater?
  12. No. All roof like surfaces are perfect for rainwater harvesting systems. Water can be collected by gutter and downpipe or by surface water intake in case of flat roofs.
    Water from roads, gardens, parking lots, is second choice, because of a greater amount and diversity of contamination, with chemicals from traffic, deteriorated earth, gravel, etc.


  13. What are the different installations and applications of Rainwater Harvesting systems?
  14. We design different systems for various applications:

    • Small systems for private homes.
    • Applications: Rainwater is used for toilet flush, laundry, cleaning purposes all around the house, watering the garden.

    • Large systems for commercial applications, for example in shopping centers, theaters, cinema hall, etc.
    • Applications: Rainwater is mostly used for toilet flushing, cleaning and watering, air conditioning and cooling of large areas, like on flat roofs.

    • Large systems for public buildings like schools, government buildings, hospitals, etc.
    • Applications: Rainwater is used for toilet flushing, watering, air conditioning.

    • Very large systems for industrial applications. Rainwater for industrial use (very large system for industrial buildings)
    • Applications: cleaning in and around the building, flushing toilets, park irrigation, mechanical refrigeration, air conditioning and cooling surface, i.e. Flat roof, process water.


  15. What are the components that make up a good rainwater harvesting system?
    1. Filters
    2. Vertical Filter called the Filter Collector – rain water is collected through more than one down pipe (smaller roof area).

      Horizontal Filter called WFF 100/150/300 – rain water is collected at one entry (larger roof area).

    3. Tank (cistern).
    4. Pressure boosting systems (pump)
    5. Suction pump, underwater pressure pump hybrid system = combination with feed tank.

    6. Pipes, fittings, valves (shut-off valve, water meter, water tap) and identification labels.


  16. What are the steps and products take part in ACT-WISY Rainwater Harvesting Systems?
    • A pre filter – Down pipe or Vortex type
    • Smooth Inlet for settlement of sediments ( in case of any)
    • Suction floating filter ( for the best part of water for the re use)
    • Multi siphon – Total quality management of storage tank.


  17. Specify the size of the filtration?
  18. WISY filters are filtered out the fine particles from the harvested rainwater having the size of 280 microns. Also 440 micron sized filter meshes are used for fine filtration.

  19. What are the performance factors of WISY Filters?
  20. WISY Filters are to be selected according to their purification performance.

    WISY Filters have high purification performance on the following factors:
    1. Efficiency.
    2. Service life.
    3. Permeation size.

  21. What is the working principle behind the WISY Filtration Systems?
  22. ACT-WISY Rainwater Harvesting Systems follows the Principle of Free flow and Adhesion. Only Natural force is used for the flow of water and hence the filter rarely or never block.

  23. How many filtrations are done in a ACT-WISY rainwater harvesting systems ?
    • Fine-filtration (Before storage) is done by the use of either Filter Collector / WFF Vortex Fine Filter.
    • Within the storage tank, Floating Fine Suction Filter provides filtration as well as the suction back of water for reuse.


  24. How does a vortex fine filter works?
  25. Rainwater enters the inlet connection in the side of the Vortex Fine Filter unit. The inlet is designed to swirl the water in a vortex-like action around the surface of the stainless steel filter below. The rainwater is drawn through the vertical mesh walls of the fine filter by adhesion, then collected and fed through the outlet to the storage tank. Debris and particles too large for the filter are flushed through to the drain outlet by the action of water flowing down the surface of the filter. More than 95% of the rainwater entering the vortex filter unit filtered and collected by this principle.

  26. What are the advantages of WISY filter?
    • Drainage safety.
    • Complete dirt separation.
    • Oxygenation of the rainwater at different stages.
    • Extremely low maintenance.
    • High water collection efficiency.
    • Eco friendly.
    • High durability and reliability.


  27. What are the challenges when installing a system, especially in different landscapes?
  28. – Assessment (calculation) of the plant

    • The tank should not have too big and/or not too small dimension. The tank should be installed underground. Reason is; water should be kept in a cool and dark place to assure longer shelf life in order to improve the water quality.
    • Security of the system. (Striving for double safety in public buildings and in the industry.)
    • Using reliable and low maintenance filters, such as FS, WFF 100/150/300 or SAGF, SAFF.
    • Selecting the correct pumping equipment (where there is no electricity a hand pump is required).


  29. Who is qualified to install a RWH system?
  30. Only installers (trained installers) should install Rainwater-Harvesting-Systems. Optimally, they should be trained by ACT-WISY Experts on rainwater utilization technology.


  31. What errors can be made when installing a system?
  32. Almost everything can be just done wrong,

    1. a filter is not used. A filter is installed incorrectly, rather than using a filter system to discard dirt, a debris collection system is used.
    2. the smoothing inlet and siphon are installed incorrectly.
    3. an overflow was not built into the tank.
    4. the rainwater is taken directly from the bottom of the tank and not from flotation.
    5. the potable water feed for drinking water is not adjusted correctly (waste of water).
    6. the cables routed out of the tank are wavy.
    7. certain lines were installed without making it possible for main water disposal to connect to the open potable water feed.


  33. What needs to be taken into consideration before installing a system?
    1. How large is the roof area (surface) where the rainwater can be collected from.
    2. How many consumers will there be. How high is the daily water demand?
    3. How high is the average rain fall? When is rainy season?
    4. Rainwater experts from ACT- WISY should be involved right from the beginning of the planning phase of a construction project.


  34. What type of materials is used in WISY Filters?
  35. WISY Filters are manufactured of stainless-steel. This guarantees the resistance to corrosion and frost.

  36. Is WISY Rainwater Harvesting Systems Regulated to any standards?
  37. Yes, the DIN 1989 regulates the Rainwater Harvesting Systems in EUROPE and many of the products are patented.

  38. Does have any possibility of clogging in rainwater harvesting filter elements?
  39. ACT-WISY RWH Systems, does not present any clogging in the filter element.


  40. Whether the oxygenation of harvested rainwater is done? What is the importance of oxygenation in rainwater harvesting systems?
  41. Oxygenation of rainwater is one of the most important steps in rainwater harvesting systems done by Smoothing Inlet. It promotes the life of the Aerobic Bacteria in the storage tank. They eat biological matter, using Oxygen and producing Carbon dioxide.


  42. What do you mean by Extraction of water in ACT-WISY RWH?
  43. Extraction of water within the storage is done with the help of Floating Fine Suction Filter. The water is extracted from the cleanest part of the storage tank; just below (10-15 cm), to ensure the water taken is most oxygen enriched.

  44. How does one ensure the water does not become stagnant after a certain time period?
  45. This is ensured due to good filtering of rainwater as well as the underground installation of the tank. As long as the water is kept in a cool and dark place, without faltering, it can be stored up to a time period of six to eight months.

  46. Is it water overflow occurs in rainwater harvesting systems? Can it controlled properly?
  47. A good rainwater harvesting systems should have an overflow condition. ACT-WISY Rainwater Harvesting Systems should control the overflow of water in a proper manner by the use of Multifunctional Overflow unit called Multisiphon. The unit is effectively a ‘U’ bend, providing a water seal. When overflow conditions occur the water is ‘skimmed” rapidly into the horizontal opening.


  48. What are the functions of Multisiphon in ACT-WISY Rainwater Harvesting Systems?
    • Drain odor elimination.
    • Vermin protection.
    • Backflow protection.
    • Overflow with skimming effect.
    • Pipe protection in case of backflow.
    • Gas barrage.


  49. What type of materials is used in pumps and pipes?
  50. WISY pumps are made of stainless steel, plastic or brass, which are suitable for use in the food industry. The tubes and pipes are also made to suit the food industry as well as the natural rubber we use.

  51. Is it substituting the potable water with by use of rainwater? How much water can be saving by the use of rainwater?
  52. Yes. We can substitute the use of potable water by the rainwater without any treatment. The average calculations and applications of rainwater without further treatment includes

    • For toilet flush – 50%
    • For laundry – 18%
    • For the irrigation purposes – 7%
    • For cleaning – 5%

    Thus 80 % of the potable water needs can be substitute and conserve by the rainwater.


  53. What is potable water?
  54. Potable water is another name for fresh drinking water. Water of sufficient quality to serve as drinking water is often called potable water.

  55. ACT-WISY Rainwater Harvesting Systems does follow any Standards?

  56. ACT-WISY Rainwater Harvesting System follows the DIN Standards. The standard series DIN 1989 -1:2001-10 specifies “Rainwater Harvesting Systems”.

  57. Does the system require any electric power?
  58. No. ACT-WISY Rainwater Harvesting Systems does not need any electric power for working.

  59. Where should I put the tank?
  60. The best place for your storage tank is below ground, where it is out of sight and the water will be in the best environment for storage – dark and cold, yet protected from freezing. Once installed the tank then effectively takes up no space on site. Installing an underground tank is relatively simple but can be disruptive on existing properties. For this reason underground tanks are best suited to new-build or major renovation projects. If you do opt for an above ground tank, try to site it where it have some shelter from hot summer sunshine, or screen it with trellis, plants etc.

  61. Piping and connections of ACT-WISY Rainwater Harvesting Systems follows any standards or guidelines?
  62. The piping and connections of the ACT-WISY Systems are according to the well defined DIN Standards. This results no restriction of flow of water.

  63. ACT-WISY Systems does present any reduction of piping?
  64. The piping of the ACT-WISY Systems does not have any reduction of piping rather request for 4’’ or higher piping subject to the Filter.

  65. How long would the water last in a drought?
  66. ACT – WISY Rainwater Harvesting Systems maintaining the water quality for longer duration up to 8 months. So we can use the filtered harvested water in the dry period without depending to any other sources.

  67. How far from the house can the storage tank be sited?
  68. Ideally within about 10m of the building, but this is not critical. The shorter the distance between tank and building, the better for pump efficiency and reduced pipe runs. However, the tank should not be so close to the building that the excavation is in danger of undermining any foundations.

  69. What is the size of tank do I need?
  70. That depends on how big a roof you are collecting rainwater from, where you live, and the level of usage in the property. We can calculate the appropriate size for your particular project, and the simplest method of doing this is to fill out our on-line quotation form. There is a common misconception that one should have a large a tank as possible; however it is very important that the tank is not too large as this can in time lead to water quality problems. You will also find that some suppliers have very limited choice of tank sizes available, so they may simply recommend what they have. We can supply tanks of any size and will always recommend the correct model for your needs.

  71. Can the storage tank be above ground?
  72. Yes, but it makes it more complicated to divert the water to the tank, and thought must go into how to arrange guttering and pipe work to ensure it is not too unsightly. It may not be possible or practical to drain the entire roof area into the tank. Consideration must also be made towards frost protection.

  73. How much maintenance is required?
  74. Very little. The only routine maintenance necessary is the cleaning of the rainwater filter unit. This is a simple 5-minute task and should be done approximately every three months. The other components of our system are effectively maintenance-free, though we do advise an annual check.

  75. What happens when there is no rain, or I use more water than I collect?
  76. An automatic mains water back-up system ensures that the system will not run dry. So if your tank gets too low, it will automatically receive a limited low-level ‘top-up’ from the mains. This will only ever raise the water level by a few centimeters, thereby leaving most of the tanks’ volume free to collect the next rainfall.

  77. What happens when my tank is full of water?
  78. When your tank is filled completely with harvested rainwater, an installed device (conveniently called Multisiphon) will divert the excess rainwater from your tank to wherever you designate.

  79. Please explain how the health and safety act is applied when installing a system?
  80. This is also specified in DIN 1989 and will continue to be verified that only approved components apply, which have a TÜV certificate.

  81. How long will the system last?
  82. Once installed correctly by a trusted installer your system will last well over 20 years.

  83. Does vehicle transportation allows in ACT-WISY Rainwater Harvesting Systems?
  84. DIN Standards clearly and properly specifies the Load class, Type of load and Max. axle load in tons .

  85. Do you provide detailed instructions?
  86. Yes, step by step guidelines are provided. For domestic installations these include excavation and ground works drawings as well as detailed mechanical and electrical guidelines.
    As you might expect for commercial systems the instructions are comprehensive including pre installation meeting, full P&ID drawings, electrical wiring drawings and commissioning check service.

  87. Does your product have any warranty?
  88. Yes. All Products provided by the ACT-WISY are covered by a two year warranty.

  89. Do you have any reference installation projects of your Rainwater Harvesting Systems?
  90. We have lot of worldwide reference projects for successful installation of our systems. Some them as follows:



  91. How much does a system cost?
  92. Pricing depends on your requirement and the local taxes. For more information, please contact us

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