06 DEVELOPMENT OF WATER SOURCES

can be utilized as an important source of water supply in areas where rain is well distributed throughout the year and where surface and groundwater are scarce

Rainwater

is the process of collecting and storing rainwater in a scientific and controlled manner for future use.

Rainwater harvesting

It is hard to determine who was the first to collect rainwater. However, the earliest known infrastructure was found in the?
It is located close to modern-day India, Pakistan, and Afghanistan, and dates back to 5,000 BC

Indus Valley

what are Rainwater Harvesting Benefits?

✓ Environment-friendly, easy approach for water requirements

✓ Uses simple technologies that are inexpensive and easy to maintain

✓ Ideal solution for water supply in areas without adequate alternative water resources (good backup source to wells and municipal water)

✓ Increases ground water level and improves its quality

✓ Mitigates the effects of drought

✓ Reduces the runoff, which otherwise would flood storm water drains

✓ Reduces flooding of roads and low lying areas

✓ Reduces soil erosion

✓ Cost-effective and easy to maintain

✓ Reduces water and electricity bills

✓ Little soap is needed since rainwater is soft

✓ Very flexible, allows expansion, reconfiguration, or relocation, if necessary

Notes on Rainwater Harvesting

Bypass the first __ to __ minutes of rainwater and filter the collected water.

The cistern be treated after every rain with a chlorine compound of at least___ chlorine

5 to 10

5 mg/l

Today, rainwater harvesting is becoming a viable alternative for supplying households and businesses with water and not just for the farms anymore. There are many countries such as?

Germany and Australia

what are the Uses of Collected Rainwater?

• Irrigation Use

• Indoor, non-potable use

• Whole house, potable use (when properly treated)

what are the Methods of Collecting Rainwater?

1. Rain Barrels

2. Dry System

3. Wet System

This method is the most common and one that many people are familiar with. This involves installing a barrel at a gutter downspout to collect rainwater. The actual barrel may be a recycled barrel or a new commercially available rain barrel

1. Rain Barrels

The pros and cons of Rain Barrels

Pros:

• Easily implemented by anyone at any residence ▪

• Barrels are readily available in your community or at various stores & websites 

• Barrels don’t take up much space so they can fit into any situation

Cons:

• Capacity is generally only 50 to 100 gallons

• Easily overflows and wastes collection opportunities

This method is a variation of a rain barrel set-up, but it involves a larger storage volume. Essentially, the collection pipe “dries” after each rain event since it empties directly into the top of the tank.

Dry System

The pros and cons of Dry System

Pros: 

• Can store a large amount of rainwater Great for climates where rainfall happens with infrequent, larger storm events 

• Can be inexpensive to implement 

• Less complicated system so maintenance is easier

Con

• The storage tank must be located next to your house

This method involves locating the collection pipes underground in order to connect multiple downspouts from different gutters. The rainwater will fill the underground piping and the water will rise in the vertical pipes until it spills into the tank. The downspouts and underground collection piping must have water-tight connections. The elevation of the tank inlet must be below the lowest gutter on the house

Wet System

The pros and cons Wet System

Pros: ▪

• The ability to collect from your entire collection surface 

• The ability to collect from multiple gutters and downspouts 

• The tank can be located away from your house

Cons: 

• More expensive to implement due to underground piping 

• Sufficient difference between gutters and tank inlet must be available

Determine the amount of water which can be collected in a year if the annual rainfall is 2,360 mm and the available collecting surface has the dimension of 5 x 10 meters


Note: One millimeter of rain falling on one square meter of roof will yield 0.80 to 0.90 liters of water depending on the type of roof

Rainwater Collection System

1. It all starts with the roof surface. Nearly all roof surfaces are fine for rainwater harvesting.

2. Gutters should have some sort of gutter protection screening in order to keep large debris from entering the gutters.

3. Rainwater can be collected from any type and shape of gutter. There is no need for a special gutter for harvesting rainwater.

4. An additional filtration opportunity is with the installation of a rain head (downspout filter) that allows for a bit of self-cleaning filtration options

5. A first-flush diverter helps to prevent the first flush of contaminated rainwater from entering the tank.

6. Another rainwater filtration opportunity is with a tank screen that is installed on the tank entry point. It also helps to keep mosquitoes and pests out.

7. Rainwater tanks come in all sorts of sizes and materials.

8. Install an insect proof flap valve on the end of the overflow pipe to keep mosquitoes and pests out.

9. An auto-fill system can be installed to keep a minimum amount of water in the tank at all times. This is very important for rainwater tanks that are connected to automatic irrigation systems in order to prevent the pump from running dry.

10. Select a pump system to provide pressurized rainwater to distribute the rainwater easier or to connect to an inground irrigation system.

11. Install an irrigation filter inline after the pump in order to catch any large debris that may have gotten through the pump

12. A water level indicator can be helpful with monitoring the water usage from the tank.

-are outcrops of groundwater that often appear as small water holes or wet spots at the foot of hills or along river banks

Springs

is a watertight collecting box constructed of concrete, clay, or brick with one permeable side

Purpose: to isolate spring water from surface contaminants such as rainwater or surface runof

spring box

-involves a simple means of obtaining naturally filtered water

-consists of a system of porous, perforated, or open-joint pipe or other conduit that drains to a receiving well

Infiltration Wells

✓It is not advisable to construct an infiltration well unless the water table is relatively _____ and the water intercepted is _____

stable
free of pollution.

• includes water from streams, rivers, lakes, ponds, seas and oceans.

• usually contains organic and inorganic minerals and needs expensive water treatment

• should be avoided for rural water supplies

Surface water