With the water crisis gripping most parts of India, we are receiving many calls enquiring about rainwater harvesting and Rainwater filtration process/Processes. Most questions are related to how the rainwater can be filtered.
Many brands of Rainwater filters are available in the market. Mostly they work under two broad principles;
- Centrifugal Force: The water enters the filter laterally and swirls inside the filter and makes a vortex. The heavier particles fall off due to centrifugal force and relatively clean water pass through the filter.
- Conventional Gravity Flow (Sand filter): Here the water enters the filter chamber after first rain separation (A method to leave out initial few minutes of rain). The water passes through series of filter media and enters the filter.
This posts is intended to enlist the main differences between the two types of filter and help people choose the right filter for their needs.
Below are the main differences between the two types of filters.
|
Sl No`
|
Centrifugal Filter
|
MSF (Modified sand filter)
|
|
1
|
Quick to install
|
Elaborate process
and time consuming for installation.
|
|
2
|
Looks very elegant
|
Looks are not great
|
|
3
|
Efficiency is 70 to 75%
|
Efficiency is
90-95%
|
|
4
|
Easy to clean
|
Cleaning is labour
intensive
|
|
5
|
Not Self-Cleaning
during rains
|
Not self-cleaning
during rains
|
|
6
|
Wall mounted
|
Ground Mounted.
|
|
7
|
Design is just few
years old
|
Conventional time
tested design.
|
|
8
|
Works on
centrifugal force
|
Works only on
gravity.
|
|
9
|
Only mesh for
filtration
|
Mesh ,graded metal,
cinder and activated carbon for Filtration.
|
|
10
|
Cannot support
rainfall greater than 80 mm/hour.
|
Can support any
rainfall.
|
|
11
|
Filtration is very
basic
|
Filtration is
elaborate.
|
|
12.
|
No sedimentation
tank possible
|
Sedimentation tank
is a part of the design.
|
|
13.
|
Loss during rains
is very substantial
|
No loss during
rain.
|
|
14
|
Minor clogs can
result in all the water getting wasted.
|
No loss due to any
clogs. However, it is important to clean the filer regularly.
|
|
15
|
No backwash
|
Backwash is
possible after every rain.
|
|
16
|
Automatic flush out
if filter is clogged
|
No automatic flush
out.
|
|
17
|
Expensive but
branded
|
Unbranded.
|
|
18
|
Standard design
|
Custom built.
|
|
19
|
Civil works is less
|
Civil works is
more.
|
|
20
|
Running cost is
almost negligible if the mesh does not break due to sand or abrasive material
getting inside the filter.
|
Running cost is
little higher
|
