Rainwater harvesting basics: Filtering the water before storage and use

Overview

Materials required and site specification

Materials Required

1. PVC drum or ferro cement
2. Filtering material – coarse jelly, smaller jelly, sand
3. Wire mesh
4. Outlet pipe for allowing filtered water to go out
5. Overflow pipe to allow excess water to flow out

Site Specification

• Usually placed below vertical down pipe
• Can also be placed adjacent to sump tank

Note

Filtering material

Placed at the mouth of the rainwater pipe, the filtering material can be very diverse.

A combination of perforated aluminium box with mesh and sand or perforated plastic bottle with mesh and gravel are efficient.

PVC drums

• Advantages – light weight, easy to transport, easy installation
• Disadvantages – cannot be kept in sun, limited capacity
• Cost - around Rs. 600. If kept in the shade, it can last over 6 years

Ferro cement filters

• Advantages – size can be made to suit the requirements
• Disadvantages – heavy, requires skill for construction
• Cost - around Rs. 1700

Stainless steel filter

• The stainless steel box filter is ready to use.
• The water enters the box from the top and passes through the mesh to the down flow pipe. Thus, stone and sand filling is not necessary.
• This filter is easy to clean
• A stainless steel filter costs around Rs. 6000

Construction technique

Step 1

Step 2

Step 3

Step 4

Caution

• Always keep the filter clean
• Remove the mesh after every rain