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