Monday, 28 September 2020

RainTap RoofWater Filter, DIY Rainwater filter, Do It Yourself RWH filter

Designed and Developed by A.R. Shivakumar

Government of India Patent Priority No. ****/CHE/2015

Raintap RoofWater filter



Rainwater collected on the roof is very pure and clean.  However, there are many substances, which get mixed with this pure water on the roof (leaves, bird droppings, dust etc.).  These impurities need to be filtered before the rainwater is stored or recharged in to the ground.   “Raintap RoofWater Filter” is a scientifically developed device, which is very effective and user friendly. This filter will effectively filter roof top rainwater from residential buildings and smaller institutional or industrial buildings.

These Raintap RoofWater Filters are simple in design and are very flexible to install in varying field conditions.

An important feature in filtering rainwater is the separation of the first flush of rainwater from the relatively cleaner and purer subsequent rainwater.


Installation of Raintap RoofWater Filter

In a building, rainwater is normally allowed to flow down from the roof through pipes.  PVC pipes are commonly used in the present times. They are cost effective and convenient for installation.  Raintap RoofWater Filter can be installed on the wall or any flat surface with suitable inlet and outlet pipe fittings. 

Depending on the roof area and the quantity of rainwater flow, the down water pipes of a building are of varying sizes.  For a residential building one or more 3 inch or 4 inch (90mm/110mm) pipes are used.


Installation of filter to down water PVC pipe

The down water pipes are placed vertically on the walls.  These pipes receive water from the rooftop through 900 bend or elbow attached to them at the top.  The other end of the pipe is left free for the water to flow down or attached with a 450 elbow or a bend to facilitate the water to flow away from the building.

RoofWater Filter comes in a carton box and will have 6 components.  

Raintap RoofWater Filter is installed at the bottom end of the down water pipe.  The pipe running down on the wall need to be fitted with a 900 elbow or a bend and connected to the inlet (rainwater inlet) of the Raintap RoofWater Filter.  The connection from the down water pipes to the inlet is through the 90mm or 110mm (3” or 4”) elbow and a connecting pipe or a reducer collar. The filter so installed must have a gap of minimum 12 inches from the floor.  This will facilitate easy flow of flush water with undesirable substances coming from the roof. Raintap RoofWater Filter has an outlet (filtered water outflow) through 110 mm Tee joint. Make sure that the Tee joint is seated on the filter body without any gap in-between. This Tee joint along with the filter cartridge can be turned in any direction (3600) in its place.  This will facilitate positioning of the filter outlet in any direction convenient for installation in the site.  This facility is provided in the filter to add flexibility in connecting the outlet of the filter in the required direction to allow filtered water to flow in to the tank.

The out flow of the filter through this outlet is connected to the storage tank.  The filter so installed need to be anchored to the wall by using screws at 3 locations.  Two screw holes are provided at the bottom of the filter and a clamp with holding socket is provided at the filter body top behind the outlet tee joint. A templet with three holes is provided in the packing carton box and the same may be placed on the wall at suitable location beside down water pipe for marking the screw holes’ location. Using 5 mm concrete drilling bit, three holes are drilled and the plastic screw plugs provided in the kit need to be pushed / driven in to these holes. The metal clamp provided in the kit need to be fixed first in to the top hole by using the stainless steel screw provided in the kit and the clamp should be facing downwards. Now the filter is placed on the wall and aligning the top slot on the filter to the metal clamp, filter body is gently pushed upwards to position the clamp firmly inside the slot on the filter body. The two holes facing the wall at the bottom of the filter need to be aligned in to the two holes with plastic plugs. Using the remaining two stainless steel screws the filter can be fixed firmly by tightening the screws in to the bottom two holes.


Inlet and out let pipe connection

Down water pipe carrying the roof water need to be connected to the inlet of the filter with proper pipe fittings (90mm or 3 inch elbow or bend and if required pipe collar). Filtered rainwater outlet need to be connected to a pipe and suitable fittings (110 mm or 4 inch) to channel the filtered water in to the water storage tank or underground sump. Make sure the elbows or bends or pipe connecting to the filter at inlet and outlet are firmly anchored on to the wall with proper pipe clamps and screws.


Raintap RoofWater filter has a drain / flush pipe at the bottom. This pipe can be either left free or can be connected with a suitable pipe to channel the dirty water while flushing or back washing the filter cartridge in to the drain or for ground water recharge.


Filter element

Filter element is made of plastic net and mesh of varying sizes to effectively filter rainwater from the roof of a building. This filter cartridge is designed for the life time of the filter and normally need not be replaced.  A cap-holder rim on the top facilitates installation of the filter element inside the filter body and also positions the filter element at appropriate height inside the filter body.  While removing the filter element from the filter, gently pull the cap-holder vertically upwards.  Make sure the entire length of the filter element is pulled out of the filter before tilting.  While installing the filter element back in to its position, make sure the mesh role enters the barrel without any crinkle.  Gently push the filter element downwards up till the cap-holder sits and positions itself on the vertical column of the filter. 


The filter cartridge cap has a spring loaded knob and the knob need to be pushed inside before pressing down the filter cartridge in to its position. The bottom of the filter cartridge has a flow stopper arrangement and sits on a rubber O-ring. This arrangement allows the water to flow out of the filter at the bottom or stop the flow when required.



·         Raintap RoofWater Filter must be installed in vertical position only.

·         Raintap RoofWater Filter can handle rainwater from a maximum of 1000 sq. ft. of roof area with 1000mm / 40 inch annual rainfall

·         Keep the Raintap RoofWater Filter dry during non-rainy days by lifting the filter cartridge and releasing the spring loaded knob on to the rim of the outlet. This will release stagnant water inside the filter body along with all the dirt collected and filtered.

How Raintap RoofWater Filter works?

The rainwater is allowed to flow from down pipes in to the filter and as the filter cartridge is in its top position, the initial flow with all the dust, bird droppings etc. will flow out. This need to be practiced during the first rain of the season. Subsequently the filter cartridge need to be in its position to close the flush valve at the bottom. Water received in the receptor flows upwards against gravity through the filter element to filter most of the floating elements and allow water to stabilize in this filtration zone.  Rainwater passing through this filter element is relatively cleaner and flows out through an outlet, which can be led to storage tank. 

Filter element is mounted on a vertical stabilizer barrel with a friction fit. Filter element need to be cleaned periodically during the rainy season to remove the impurities trapped and there by keep the filtration system clean.  In the event filter is not cleaned and the filter element is getting clogged, “Raintap RoofWater Filter” has a safety feature built into it.  The water pressure pushes out the clogged filter element from the stabilizer barrel and allows the water to flow out freely from the drain pipe at the bottom.  This safety feature will avoid flooding of the rooftop because of clogged filter.  For normal working condition, filter cartridge need to be in its position closing the bottom drain pipe.


Maintenance of filter


Back wash arrangement is provided to clean the filter cartridge. A hose connector provided at the top of the filter cartridge need to be connected to your tap with a hose pipe. Make sure the filter cartridge is in the open position by pulling the filter cartridge upwards till it pin comes out and the cartridge sits on the pin. This will allow the dirty water to flow out at the bottom. By allowing the tap water through the filter cartridge back wash can be achieved and the dust and other impurities embedded inside the filter cartridge get released and flow out through the bottom pipe. When the clean water start flowing out at the bottom or after three minutes of back wash, the tap water flow may be stopped and filter installed in its position for filtering rainwater.  

When the rain stops, flush the filter by gently lifting the filter cartridge from its position until the cartridge stands on the spring loaded knob.  The water with all the filtered dirt gets released and washes off.  After five minutes, push the filter cartridge back to its position by pressing the spring loaded knob.  Take care to position the filter cartridge correctly in its position and the bottom stopper sits correctly on the O-ring.


Wednesday, 19 August 2020

RWH App live demo from RainmanSkumar

Rainwater Harvesting Do It Yourself App

Web link:

Google Play Store :
rwh advisor
Designed and Developed by : A R Shivakumar
in Association with

World Environment Day web series from ICCW IIT Madras
A R Shivakumar live on 1st June 2020 YouTube link :

Do It Yourself Areca / Betel Nut Stool

 Do It Yourself Areca / Betel Nut Stool

DIY from ARS

Build a Leisure time stool from old paint bucket and pieces of areca nut trunk very rugged and easy on maintenance

Be environment friendly, reuse used paint buckets, If not, old plastic items like paint buckets, drums and cans are burnt/melted in kilns to make recycled plastic items and pollute the environment with highly toxic fumes and soot .....

Materials required :

1. One 20 litre empty paint bucket

2. Three pieces of Areca nut trunk

3. Wood screws 3mm dia 40mm long

Tools required :

1. Angle cutter / grinder

2. Screwdriver

3. Handheld drilling machine (optional)

Thursday, 4 June 2020

Do It Yourself Rainwater Harvesting APP

Rainwater Harvesting Do It Yourself App

Web link:

Google Play Store :
rwh advisor
Designed and Developed by : A R Shivakumar
in Association with

World Environment Day web series from ICCW IIT Madras
A R Shivakumar live on 1st June 2020 YouTube link :

Monday, 13 January 2020

Can we protect our precious ground water on the sea cost of over 7500 kilometers of Indian cost line?

Can we protect our precious ground water on the sea cost of over 7500 kilometers of Indian cost line?

Our country - India is one of the richest country with its natural resources - gift of nature
India has over 7500 kilometres long sea cost and has the most fragile ecosystem. Ground water extraction along the sea cost has encouraged saline water intrusion to several kilometres inland. Ground water being the major source for domestic as well as industrial use has touched alarming levels of TDS. Water softeners and largescale water treatment plants are the order of the day for both domestic and industrial water requirement (unsustainable)
It is time we take scientifically correct and simple measures to harness rainwater and protect our ground water- Sustainable management

Ganjam, Odisha - Case study of Grasim Chemicals

Water pumped                                          2360 kld
Water supply on the way to villagers         500 kld
Water used in the plant                            1860 kld
Raw Water Quality TDS                            2600
Annual Rainfall                                         1238 mm

Road side drain to collect rainwater

Cement ring well infiltration gallery
Roof top rainwater from most of the buildings in the colony is harvested and being recharged in to the ground.
RainTap RoofWater filters are mounted on the wall to filter roof top rainwater from the buildings and used rainwater is used for domestic needs as the rainwater is purer than any other source in the colony.
Accelerated recharge wells

Testing of percolation of water through recharge wells 

Large scale ground water recharge at the ‘Rushikulya’ river bank:

Three borewells of diameter 300 mm at depth of around 46 meters are the source of water on the bank of Rushikulya’ river.
Only two borewells are being used at present. The third borewell is not in use and is sealed from the top.
The percolation pond near the borewells has around 30,000 sqm catchment area and impound water by creating an impervious bund using HDPE liner. Recharge of rainwater through sub soil and augmented by drilling two recharge shafts with perforated / serrated casing pipe to a depth of 40 meters. The third borewell which is not in use is also in the water impounding area close to the bund. This borewell can also be used to recharge water as this is not being used to with draw water.
Perforated pipe ground water recharge shaft

HDPE lined rainwater collection pond for high volume groundwater recharge

To enhance the ground water recharge capacity, additional catchment of around 90,000 sqm area is developed near the pump house and the care taker house. Two impounding bunds with HDPE lining are created to form two separate ponds to collect rainwater.

As the catchment areas have water flowing in different directions, few channels are dug to lead the rainwater towards ponds with impervious bunds.

Water harvesting in the open field of the Grasim colony is established by creating precast cement ring wells for accelerated ground water recharge. The rainwater collected in the box type drain is intercepted at intervals and the water is diverted to the recharge wells created next to the drain.

To create awareness for water conservation and rainwater harvesting, over 30 schools are identified and the surface runoff from the playground and surrounding area of the school buildings is diverted to precast cement ring wells for accelerated ground water recharge.

Wednesday, 1 January 2020

Rainwater Harvesting Act 2009, 72 A - BWSSB


“72A. Obligation to provide rain water harvesting structure

Within nine months from the date of commencement of the Bangalore Water Supply and Sewerage (Amendment) Act, 2009 every owner or occupier of a building having a sital area of 2400 square feet and above or every owner who propose to construct a building on a sital area of 1200 square feet and above shall provide for rain water harvesting structure in such manner, with such conditions as may be provided in the regulations failing which the Board may cause such rain water harvesting structure and recover the cost from the owner or occupier, as the case may be, arrears of land revenue.”

BWSSB Guideline for Rainwater Harvesting (RWH)

Minimum Requirement:

Rainwater storage (surface tank or underground sump) and ground recharge (RCC precast ring well) of minimum 20 liters per square meter of roof area and a minimum of 10 liters per square meter of paved open space provision shell be made. The open well / recharge well of depth of 3 meter (minimum) and diameter of .9 meter (minimum) with out filling in the well (like aggregates, jelly, sand etc.) provision shell be made.

You may store rainwater in a tank / sump or recharge rainwater in to the ground through a well or you can use a combination of these two to achieve the stipulated capacity of ‘X’ liter. Where X = roof area in sqm x 20 + paved open area in sqm x10.

The open well should be of minimum 3 ft diameter and 10 feet deep.
Ground water recharge should not be attempted at places where the ground water level is very high and at places where hard rock strata exists at shallow depths. It is suggested to build a shallow sump or install a surface tank for storing harvested rainwater.

Rainwater from the roof and through a filter should not be allowed directly in to a live borewell. It is advisable to allow the filtered rainwater in to an open well beside the borewell. In case of a failed or very low yielding borewell, you may allow a portion of overflow from your tank / sump which collects filtered rainwater from the roof. However a skilled person’s advice is required before recharging the borewell directly.

Government of India, Film Division presents 'Rain Man'