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Modern Technologies in
Rainwater Harvesting
Fritz Poerschke, Director R&D - WISY AG Germany
THE MAGIC OF
H2O
RainAll Sweetwater has once been Rain
Rainwater Harvesting Is A Part Of Water Management Solutions
o Storage of rainwater for utilization in a vessel instead of direct infiltration into the groundwater
o Advantages of RWH
o Merging modern and indigenious technologies in rural areas
o Creating awareness and carry RWH to more popularity a need is:
• to create jobs
• to create responsibility
• to include women in decision making processes about water issues
How Does Modern Rainwater Harvesting Work?
1. Collection
2. Filtration
3. Storage
4. Extraction
5. Utilisation
Design & Construction Details Of Modern Rain Water Harvesting
o Learnig from History
o Four Steps To Ensure The Best Possible Water Quality
1. guidline for best types of filter
2. smooth inlet to ensure interaction between the stored water and the sediments
3. overflow device to burst the surface tension for removing swimming particles
4. floating suction
o Storage of Harvested Rainwater in cold, dark and a cleanest possible storage vessel
o The discussed four steps are the same: in high tech rwh system in a Mall or a simple rwh system in rural areas .. the difference is only in material and products.
1. Collection
- All rooflike surfaces are perfect.
- Water can be collected by gutter and downpipe or by surface
water intake in case of flat roofs
- Water from roads, gardens, parking lots, are second choice
because of possibly a greater amount and diversity of
contamination.
Rainwater Harvesting
2. Filtration
- Rainwater must be filtered before it is stored.
- Simple physical filtration is sufficient
- The filter removes particles
like sand, dust, tile pieces etc.
to ensure long life of pumps, sealings, and faucets
- The filter removes biological matter
leafs, Insects, birdsdrop, rodents, etc.
to ensure microbiological stability
Rainwater Harvesting
2. Why Filtration Is A Microbiological Need ?
1. Bacteria are essential for human life !
e.g. Coli Bacteria live in symbiosis within the human intestine,
without them digestion is not possible.
2. Bacteria cause diseases and foulness
Oxygen and the distribution of oxygen in the stored water makes the whole
difference
Oxygene prevents anaerobian reactions and promotes the life of the aerobian
bacteria.
They are:
Eating Biological matter,
using Oxygen,
producing Carbondioxide
That are the good ones which we whish to have in the stored rainwater!
4. Rainwater Harvesting
Examples of existing filtration systems
Example 1: Sand & Stones Filter
Example 2: Filter with a horizontal sieve and rinsing water
Example 3: Filter with a inclined sieve
Hon. Eng. Norbert Winkler had a genius idea which is working much better:
Filtering by ahesion!
The principle:
water jet is attraced by a
solid surface and it changes
its velocity, e.g. not only its
speed but also its direction
changes!
WISY Filter Collector
for vertical pipesWISY Vortex Fine Filter
for horizontal pipes
The result: WISY filter with a perpendicular sieve!
3. Storage
Rainwater should be stored in a cool and dark place
at best underground
Above ground container should prevent sunlight inside the
tank. Good protection from the sun is necesary to avoid
warming of the water.
Big containers can be divided to keep a certain amount of
water, for example for use as fire fighting water
Rainwater Harvesting
4. Extraction
The best method is the use of a submersible pressure pump
Extraction by suction pump is possible when special care is
taken that the hose stays filled with Water, including a non
return valve or automatic filling device.
Placing the pump by the side of the tank is possible but has
the risk of water loss through the pump or bad sealings
Rainwater Harvesting
WISY Rainwater Harvesting System
1
Step 1:
Filtration of Rainwater
Step 4:
Overflow removes floating particles
Step 2:
Water enters cistern softly and oxygen is distributed evenly
Step 3:
Extraction of water in the cleanest level of the cistern, by floating filters
1
2
3
4
4 Steps To Clean And Store Water
WISY Vortex Fine Filter
- For horizontal pipes
- Filtration with 0,28 mm mesh Size
- Self cleaning
- No energy consumption
- Oxygenation of filtered water
- Automatic transport of dirt
- Three sizes
Pipe diameter 100 mm
Pipe diameter 150 mm
Pipe diameter 300 mm
Step 1:
WISY Rainwater Harvesting System
WISY Filter Collector
- For vertical Downspout Pipes
- Filtration with 0,28 mm mesh Size
- Self cleaning
- No energy consumption
- Oxygenation of filtered water
- Automatic transport of dirt
-
WISY Rainwater Harvesting System
WISY Smoothing Inlet
- Distribution of the fresh water
In an upward direction
- Slows down speed of fresh water
- Allows new particles to settle
- Keeps old sediment undisturbed
- Spreads the oxygen from
fresh water in the tank
Water Inflow
Dispersed Water
and oxygen
Soil sediment
WISY Rainwater Harvesting System
Step 2
Floating fine suction filter
- For highest functional security
of your pump.
- For the extraction of rainwater
out of cisterns and other
storages, ponds and wells from
the cleanest part of the tank.
- The floating ball is made of
ecologically harmless
polyethylene, the other
components of stainless-steel.
WISY Rainwater Harvesting System
Step 3
- Multifunctional overflow unit
- Made of impact-resistant ABS plastic.
- Connects to an overflow pipe.
- Removes surface debris.
- No drain smells,
- Prevents rodents from entering into
the tank
- Prevents sewage backwash from
entering into the tank
Multisiphon
WISY Rainwater Harvesting System
Step 4
• Local and decentralized availability with little demand for
Infrastructure
• Rainfall is independent from political and financial situations
• Decentralized Rainwater collection reduces fast water runoff
• Ability of collecting Rain makes us independent from
weather extremes
• Reduction of flooding
• Rainwater is free of minerals, irrigated soil stays fertile
Rain Harvesting Is Not The Solution Of All Water Problems
But
There Is NO Solution Without RWH !!!
Parameter Unit
Result
National
Standard For
Drinking Water
Quality
Test MethodPanasonic
WarehouseSubang Jaya UITM 1 Lagenda
Turbidity NTU 0.43 1.13 0.73 0.65 <5.0 HACH 2100P
Colour PtCo/TCU 1 4 3 1 <15 TCUPHARO 100
METHOD 32
Hardness as
CaCO3
mg/L 36 32 39 34 <500HANNA hardness test
kit
TDS mg/L 38 45 50 33 1000 TDS Meter
Bacteria
Presence
/Absence
test
Cfu/ml ND Coliform = 16 ND ND ND (0)
3MTM PetrifilmTM
E.coli/Coliform
Count Plate
pH - 6.25 7.29 6.82 6.34 6.5-9.0 HANNA pH test pen
RAINWATER QUALITY TEST REPORTS
easy and reliable
water testing
quality of rainwater
Saftey and Maintenance
Best Practice Is To Avoid Or Minimize Water Usage
... Wherever Possible !
some Examples:
• Water-saving tapware
• Toilets without water flushing system
• Using grey water
• Drip irrigation in agiculture