NCWR

About NCWR

Rainwater harvesting

In a nutshell

In this activity we become “engineers” and see how a rainwater harvesting system is working.

45 min

10-13 years old

In class

Our objectives

In this activity you will:

  • Find out about the operating parts and functions of a rainwater harvesting system.
  • Learn how we can use the collected rainwater.

Stop and wonder

In your groups discuss about the following:


  1. Did you know that till the recent days in various Mediterranean islands, many houses kept rainwater harvesting .
  2. Today, in several cities around the Mediterranean, many new buildings are equipped with rainwater collection systems. Why? Where do you think this water can be used ?
  3. In many European cities, places like sports’ courses and airports are equipped with rainwater collection systems. Why so?

Play & learn

How can we collect rainwater?

If you wish to collect the rainwater, what equipment would you use? Here are some ideas by students!

 rainwater-harvesting quiz-hotspot
1
2
3
4

Play & learn

The  rainwater harvesting system

  • The catchment surface is where the rain falls: a roof, the terrace, etc.
  • A sieve (or net) is placed at the opening of the gutter (like the windows sieve) to retains debris, leaves, etc. from the rainwater .
  • Gutter  or drainage pipe is an open horizontal or closed vertical pipe that lets rainwater flows inside it.
  • Filter: to further clean water from small sized solids (dust, etc).
  • A tank to store the water; made of cement, plastic, metallic (placed at the yard or the basement; we need to have access).
  • A pump to move water upwards.
  • An overflowing siphon/pipe leads the excess of water out of the tank
  • control valve to control the flow either to the tank or the yard.

Match the parts of the system to the right spots:

 rainwater-harvesting quiz-hotspot
1
2
3
4
5
6
7
8
  • 1 1 catchment surface
  • 2 2 sieve (filter)
  • 3 3 gutter / drainage pipe
  • 4 4 filter
  • 5 5 pump
  • 6 6 tank
  • 7 7 overflow siphon
  • 8 8 control valve

Stop and wonder

In your groups, discuss about the following:


  1. Even when the tank is underground why we need to have access to its opening?
  2. Which season we need to clean the filter?
  3. The control valve gives us the option to choose whether to direct the rainwater to the tank or not. In which case you think that the rainwater might be unwanted?

 

Play & Learn

How do you think we can use the collected rainwater? We can use it (choose the right options) ...

It is appropriate for watering our garden, flowers and vegetables.

This way we achieve an important water saving!

Collected rainwater can be potable if disinfected because it might contain microorganisms. Disinfection takes place using specific filtres or chlorine or UV rays. In any case, before we drink it it is necessary to have it tested from a chemical lab.

Rainwater does not contain salts, thus, is proper for washings. Actually, certain washing machines have been manufactured to use rainwater as input. However, if we do not disinfect the water first, we cannot do the dishes or wash our clothes with it.

Rainwater does not contain salts and thus, women, back in the old times, preferred it for washing their hair. Today, when installing a modern rainwater harvesting system we avoid bathing with it because we do not know if it contains microorganisms. It needs disinfection and lab test in order to use it for showering or drinking.

It can be used for such cleaning purposes

Activity

What do we gain by collecting rainwater?

  • We reduce water consumption from the water supply network.
  • We reduce the water bill.
  • We reduce the risk of flooding, particularly when is  large-scale structure (see Rainwater Harvesting in practice Section).
  • We take advantage of a good quality, enough clean water that would otherwise go lost, end up in the sea.

Apart from households and buildings, rainwater can be collected at large-scale installations and sites such as airports, courses, squares, valleys and slops, to be used for watering the urban green, irrigating the crops, etc

How much rainwater can you collect at your school?

If your school has a water tank, you can easily calculate how much rainwater it collects within a year. Even if there is no tank, you can still calculate how much rainwater could have been collected if you know:

  • The area of the catchment surface (in square meters,m2) . This information can be obtain by the school director or you can measure the building’s perimeter and then, calculate it.
  • The average rainfall of your town (in millimeters per year, mm / yr).  You can find this from the webpage of the Meteorological Service/Institute. Then, the amount of rainwater that can be collected in a year (in cubic meters, m3) is:
Area (m²) x Average annual precipitation (mm) x [runoff coefficient] *** = .... m3

What is a run-off coefficient? We usually have some leaks or losses (e.g. due to evaporation at the collection surface). So we use a “run-off coefficient”, a number that expresses these losses and it depends on the material by which the collection surface is made. For instance, it is about 08-0.9 for metal; 0.75 to 0.9 for concrete surfaces; 0.8 – 0.85 for gravel; 0.5  for clay tiles, etc.

Water shares


Water meter

I liked this activity . . .

Way forward

Surfing around the internet

Watch here a short animation about the rainwater harvesting system that has been installed in a Primary School in Malta.

Dive in

The water cycle in a bowl! if you want to  make rain through a model of the water cycle!

Rainwater Harvesting Systems in practice if you want to read more  about an installation/construction of a rainwater harvesting system!

Go back to the homepage!

The water basins

Water in the city

Desalination

Do you know about grey water?

Rainwater harvesting

Greywater recycling in practice

Wastewater treatment

The water cycle in a bowl!

Waterworks through time

Climate change challenges

Rainwater Harvesting Systems in practice

Reduce-Reuse-Recycle

Water resources

Where do I begin?

The water basins

In this activity we learn what a water drainage basin is and why it is important for the experts to study it.

Continue!

Water in the city

What is the "urban water cycle"? Which are the important aspects of water management within a city environment?

Continue!

Desalination

Let's find out how sea and brakish water can become a freshwater resource!

Continue!

Do you know about grey water?

Let's find out what "greywater” is and how we can use it!

Continue!

Rainwater harvesting

Can we collect rainwater? And how to use it? Let's find out!

Continue!

Greywater recycling in practice

How a grewywater system is installed? Let's find out!

Continue!

Wastewater treatment

In this activity we are informed about how wastewater is treated and what we can do with the treated wastewater.

Continue!

The water cycle in a bowl!

Let's travel within the water cycle!

Continue!

Waterworks through time

Let's discover the story behind the historic fountains, cisterns and aqueducts of our town!

Continue!

Climate change challenges

Time to discuss about climate change, causes and impact and how we can cope with it.

Continue!

Rainwater Harvesting Systems in practice

What are the various types of rainwater harvesting systems? Let's find out more about them!

Continue!

Reduce-Reuse-Recycle

What is my water footprint and how can I reduce it?

Continue!

Water resources

Discovering the water resources of our region.

Continue!

Where do I begin?

Let's see why it is important to know about water in our region.

Continue!