• Rainwater harvesting is the collection and storage of rainwater for reuse on-site, rather than allowing it to run off. These stored waters are used for various purposes such as gardening, irrigation, etc.
• The components of the rainwater harvesting system include  Catchments, Coarse mesh, Gutters, Conduits, First-flushing,  Filter, Storage facility.
• Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like polyvinyl chloride (PVC) or galvanized iron (GI), materials that are commonly available.
  
• Hence Conduits are the component of the rainwater harvesting system.
• So, the correct answer is 'Conduits'.

• Rainwater harvesting is the collection and storage of rainwater for reuse on-site, rather than allowing it to run off. 
•  These stored waters are used for various purposes such as gardening, irrigation, etc.
  
• Broadly there are two ways of harvesting rainwater. They are Surface runoff harvesting and Rooftop rainwater harvesting.
  
• Hence Rooftop and runoff are the types of rainwater harvesting methods.
• So, the correct answer is 'Both A and B'.

The population is a major cause of water shortage. Water is polluted when industrial wastes are deposited into water bodies thus making it unfit for human consumption. Thus there is a need for water security.

Scarcity of water is the under or non-availability of usable water. This water presence in the ground is very less and this may sometimes lead to draughts.

The following techniques are used for rainwater harvesting
 (1) Rooftop rainwater harvesting: The rainwater is collected from the rooftop to a storage tank, through pipes.
(2) Water is allowed to go into the ground directly from the roadside drains that collect rainwater.

There is shortage of water in many parts of the world. Hence, it is very important that water is used carefully to avoid shortage of water.

Rainwater harvesting is the process of collection of rainwater from surfaces on which rain falls, filtering it and storing it for multiple uses  'OR' the method of collecting, storing and distributing rainwater for different uses. 

The collected water can be stored for direct use or it can be diverted for groundwater recharge.

Following are true about Rooftop rainwater harvesting:
1) The rainwater is collected from the rooftop to a storage tank, through pipes.
2) This water may contain soil from the roof and need filtering before it is used.
3) Instead of collecting rainwater in the tank, the pipes can go directly into a pit in the ground.

Formation of $H _{2}CO _{3}$:

Region having high annual rainfall and large population and  Region having high annual rainfall but water is highly polluted regions have high water scarcity problem because of high use of water tends to water pollution.Polluted water is unusable for humans.

Rainwater harvesting cannot be practiced in Bathroom as the bathroom is a closed area and the rain water cannot directly comes into it.

Rainwater harvesting can be implanted in an open area where the rain falls directly.

Rainwater harvesting is the accumulation and storage of rainwater for reuse on-site, rather than allowing it to run off. All the water was collected into a well and helps in raising water table.

'Catch it where it falls'  is the basic idea behind the rain water harvesting. Rain water harvesting is the accumulation and storage of rain water for reuse on site rather than allowing it to run off.