The KRS dam on the Cauvery has only 1.03 tmcft of water. This is sufficient for Mysore, Bangalore and Mandya for only 10 days. This is one report in the press today. We need 600 cusecs of water to flow in the Shiva Anicut for us to tap water into the Netkal balancing reservoir. We will then pump 1110 MLD into the city says the BWSSB according to another statement.
The neighbour drilled a bore-well for two days. I struck water at 750 feet and got 2 inches of water he says. The rain gauge on our office has measured 300 mm of rainfall so far since April. What do these numbers mean? How do we understand them in a common language? Here is an attempt to explain some of them.
1 Tmcft is One thousand million cubic feet of water. This is 28316.85 million litres of water. If there was 1 Tmcft of water in the dam and this was to be pumped equally, every day for 365 days in a year to the city, 77.58 million litres per day (MLD) would be available to the city.
By the way 1 cubic metre of water is 1000 litres of water
Cusec is a measure of the rate of flow still commonly used by the irrigation department. 1 cusec is one cubic foot of water flow per second. It translates to 28.32 litres of water per second. If 1 cusec of water is released from a dam for the whole day 2.45 million litres of water would have flown in the river in the 24 hours.
A common mistake made by many is to add up cusecs. If 600 cusecs of water was released for one day and 900 cusecs the next day it does not mean that 1500 cusecs of water was released in 2 days.
Borewell: A common way to describe the yield of a new bore-well is to say that 2 inches of water was struck. What does this ‘2 inches’ of water mean? It is actually the free, unrestrained flow of water from a Borewell over a 90 degree V notch.
Using a complex formula, calculations are made. Here is an approximation of the litres per hour flow
Height Flow in litres per hour
½ inch 95 litres per hour
1 inch 600 litres per hour
2 inch 3400 litres per hour
3 inch 9300 litres per hour
4inch 19100 litres per hour
Rainfall: Rainfall is measured in typical standard rain gauge as prescribed by the Indian Meteorological Department. Typical measurements are taken at 8.30 a.m. in the morning and reported as mm of rain.
For those harvesting rainfall, here is a good way to calculate the volume of water falling on a roof. Suppose you have a roof area of 100 square metres and the rainfall on a particular day was 10 mm. The total volume of water that fell as rain on your rooftop would be 100 x 10 = 1000 litres of water.
Conclusion: Knowing the numbers is a very important step in water literacy. Water literacy leads to water knowledge and better management of the resource. With years perhaps water wisdom will also come.
In the second case a determined drive by an IAS officer called Manjula who was the then DC of Bangalore Rural District , persuaded recalcitrant elected reps and govt officials at the Gram Panchayat and village level to talk to people and persuade them to build toilets. People by and large put in the effort and built toilets and sometimes bathrooms too putting in their own money.
In the first case , though toilets have been built they are not used since people prefer the great outdoors.
On the other hand efforts are being made to build Ecosan toilets so that farmers too can benefit from the toilets .
The monsoon is a magical time in India. The season of the wind, clouds and rain brings joy to a parched land. Rainwater to India is a gift from the Indian Ocean. The clouds do the couriers job and the winds play assistant. When i falls on our heads it is good to keep a clean catchment and then collect it in Rain barrels. You can then put this soft water which is slightly acidic to good use . Apart from drinking the water (after checking for purity) you can make coffee from it.
A clean roof , a good cloth filter and a food grade HDPE tank to store rainwater
Clean soft water slightly acidic and with a high Dissolved Oxygen content – rain
Here is Indian Ocean coffee for you
My coffee Percolator …filter we call it in this part of the world
The percolator container comes on top
Ground coffee powder goes in – Arabica with 5 % chicory is my favourite
The cover plate on the coffee powder , to hold it steady
Rainwater goes in – cold not hot – so that the Oxygen is not lost and there is an earthy taste
Then you put the top lid and wait
Rainwater percolates through the coffee powder..take it from the bottom container and percolate it again
Indian Ocean coffee is ready
Then again you can also make rice using rainwater
Rice , rainwater in a pressure cooker
Soft tasty white rice …eat the monsoon flavour
Add milk and sugar as per taste and heat if you like. I prefer it cold and neat
Well digging has been the forte of the ‘Mannu Vaddar’ community in Bangalore. They are the people who work with earth for many centuries. They have dug the many lakes of Bangalore and also the many wells that dotted the landscape. Then their cousins the ‘Kallu Vaddars’ would take over and line the well with stones . The craft is at least 6000 years old in India.
The stone lined wells of South Karnataka
Since the 1980 ‘s , especially during a period of 3 continuous years of bad rainfall, the construction of wells stopped and people shifted to the bore-wells. This rendered the well diggers jobless and they shifted to digging foundations for buildings as well as digging pits for toilets.
With the recent rainwater harvesting interest in the city and the coming in of the bye-law , wells are being dug again, only this time to recharge water from the rooftops and from storm water drains.
Muniyappa – is now known as ‘Bhavi’ Muniyappa or Well Muniyappa in Bangalore
People like Muniyappa have dug more than 2000 recharge wells . He is a legend in the community. Of course strong competition has cropped up and there are many more well diggers in Bangalore.
A good policy , such as the rainwater harvesting policy , introduced in Bangalore not only works for ecological benefits such as increasing the groundwater table , preventing floods , supplementing the water needs of citizens but also provides social benefits such as work to many well diggers. This is truly the ‘green economy’ kicking in and traditional crafts being revived.
Even though the well mentioned by Mr Balsubramanian is more than 30 years old he still remembers Arumugham who dug it for him, everyday he says.
The memory of the well is crucial to Bangalore. On groundwater will depend the city s future. Well diggers and the recharge wells they dig will become the water warriors of the city. Time to salute ’em.
It is not only Bill and Melinda who are funding innovation in the toilet business :).
When millions of people all across India start to build toilets in rural areas and in small towns they do not have a sewerage system to connect to. They usually build a single pit lined with concrete rings and connect the toilet to it. In India the toilets too are pour flush toilets and not the dry toilets prevalent across much of Africa.
Eventually these pits do fill up, depending on many factors such as the depth of the toilet pit , the number of users, their diet , the soils ability to infiltrate water etc etc.
The pan for an Indian toilet – this has a water seal too
A single pit toilet lined with pre-cast concrete rings
Eventually they will fill up
Jugaad to the rescue – These tablets if placed in a full pit will ‘burn’ it and reduce the filling making it possible to use the pit for more time
These are called ‘pit medicine’ in Kannada and are available across many small towns. Each set costs Rs 50 ( 1 US $) and is a single time use.
Taa-daah …Honey-sucker to the rescue. Will empty the pit toilet in minutes.
Now imagine a set of tablets which can also sterilize the pit content and kill all pathogens . The pit sludge can then be easily removed using the ‘Honey-sucker ‘ and spread out on the fields in the rural areas and in the small towns to act as fertilizer for the crops.
..and oh by the way , one of the fastest growing business around small towns and villages is in these pre-cast concrete ring making. All you need is an empty site , a steel mould for pouring the concrete , some cement and GI wires /streel rods and you are in business. As there is a huge government push for sanitation demand is picking up in villages for these rings for the toilet pit
All over South India , in small towns and large villages, concrete rings for pit toilets are being made
This is what we will be working at in the near future.
Rainfall measurement is very helpful in understanding the weather around you. For example if you want to harvest rainwater, understanding rainfall patterns and quantities helps to get a good design for the storage and recharge. Here is how you can make a cheap rain gauge and start putting it to use this monsoon.
You need a 1 litre or a 2 litre PET or PVC bottle. The bottle should have a flat base and be vertical for the most part.
Cut the bottle at the place it starts to curve and taper. Remove the cap
Using a hot knife helps. Be careful while using it though.
Flip the cut portion and place it like this in the bottle
This will ensure all rain comes in to the bottle and does not evaporate
Take a 6 inch plastic scale and tape it to the bottle from the outside , like so
Fill water in the bottle till the zero mark of the scale. This will give the bottle stability as well as do a ‘zero correction”
This is how your rain gauge will look from the top
Place the rain gauge in a clear place with no trees or any structure to obstruct rainfall. If necessary support it with bricks on the sides to prevent wind from toppling it over.
Take readings everyday at 8.30 a.m. and enter it to a monsoon diary. After the measurement is taken empty the rainwater into a pot and bring the water level to read zero on the scale.
Remember these are approximate measures and it does not matter if the bottle is a 1 litre of a 2 litre or even a 10 litre bottle as long as the bottle is vertical.
At the end of the June- September season on October 1 st add up all the rainfall measurements that you have taken. How much did it rain in your place? Was monsoon 2013 good ? What is the average rainfall for your place? Where will you find this information?
As the city expands and buildings fill it up to find open space becomes difficult. In Bangalore in the small sites it is impossible to have even a small garden. About 60 to 70 % of inner Bangalore will be roofs as a look at Google earth will show.
For an urban planner like me and for Chitra an Architect this was a fascinating finding. What do roofs do and how are they designed? Unfortunately we seem to poorly design our roofs apart from ensuring that they keep out the sun, rain and the elements. Most of the concrete and steel in the roof goes towards carrying its own self weight. Architect Laurie Baker had shown that we could make roofs lighter by using a filler slab. Waste tiles were what he used as a filler material. This made roofs lighter, require less concrete and steel and also look beautiful from the inside. Scientists such as Prof Jagadish and Dr Yogananda had designed the flat tile arch panel roof, which was precast and which also was structurally lighter, more efficient and had a different aesthetic quality. We therefore used these roofs in our house.
A filler slab roof using Mangalore Tiles as a filler material
A calculation on what was happening the outside of the roof was also interesting. Almost all the rain on the building site falls on the roof. In Bangalore it can rain 970 mm in an average year. This meant that our house roof with an area of 100 square metres had 97,000 litres of pure rainwater falling on it. With the idea why allow it to go waste, we started to harvest it? This harvesting was done at many levels.
From the staircase rooftop which had an area of 10 square metres, we placed a Rain barrel and collected the water on the roof itself. A small platform was designed and the 500 litre Rain Barrel placed on it. On the staircase roof we placed a gutter to collect the rain. This came down into a vertical pipe with an end cap called the first rain separator. During the first rain and subsequently when we want to clean the roof or the rain gutter we open the cap and the dusty water flows out through the first rain separator. Then after a ‘Y trap’ rainwater flows in through a ‘dhoti filter’ into our rain barrel. We checked the rainwater quality using a H2S strip test and found the water potable. Sometimes when there is slight contamination we use a method called SODIS (Solar Disinfection) to treat the collected rainwater for drinking purpose. Here you fill a PET bottle with the rainwater and leave it in the sun for 5 hours. The water is now sterilized and can be brought into the house cooled and is ready for drinking. This is not a low cost solution for water treatment but a no-cost solution. Our annual requirement of drinking cooking water comes from this rain barrel alone.
We also have an Ecosan toilet on the terrace. This pan in the toilet separates solids and liquids at source. We collect the urine in a barrel, dilute it and use it as a fertilizer for our terrace garden. The solids are covered with ash every time we use it. This is then transferred to some Blue drums we have kept on the terrace and again covered with earth or straw. We then plant trees in these drums. Trees such as Papaya, lemon, curry leaves, sapota are planted and they grow well. No waste from our toilet on the terrace leaves the roof.
The rainwater falling on the Ecosan toilet too is collected in a 200 litre rain barrel and used for ablution purpose.
We have a box type solar cooker to cook our lunch on the terrace. A solar water heater heats water for bath and for the kitchen. During cloudy days we use a ‘Gujarat boiler’ which uses bio-mass for the water heating. The Gujarat Boiler also generates ash for us to use in the Eco-san toilet. We have planted many trees in front of the house and the twigs and branches from the trees are used for the Gujarat Boiler.
Next we have placed a bathroom on the terrace itself. This also has a front loading washing machine which is one of the most water efficient ones in the market. We collect the water from the bath we have on the terrace bathroom as well as from the washing machine in a small ferro-cement tank placed just below the roof slab. We then pump it up to a planted reed filter to clean up the grey-water using a small pump. The reed filter is Cattails – reeds found in lakes- placed in 4 blue drums. In a fifth drum we have sand and gravel filter to clean up the grey-water further. This treated grey-water is then used for the terrace garden where we sometimes grow rice paddy. Some extra grey-water is also used for flushing the toilet in the ground floor. No greywater is allowed to go waste.
The rice on the rooftop grows well on even a small area. We place 2 sheets of a pond lining material called Silpaulin with a brick edging. The sheet is then filled with a mix of compost, vermi-compost and red earth up-to a depth of 2 to 3 inches. Rice paddy is then planted in it. The water required for the paddy comes from grey-water alone. For the fertilizer the urine from the Eco-san toilet is used. Kitchen waste which is composted is also added to the soil. We have had productions of paddy to the tune of 1 kg per square meter. We have also found that we can grow 4 crops of rice in a year. Millets can also be grown instead of rice. Vegetables such as tomatoes, brinjals, lady-fingers, chilies all grow on the terrace though the monkeys who frequent this place can also be a nuisance at times.
A small wetland has also been created in a ferro-cement tank where different plants and fishes occupy and clean water.
Solar photo-voltaic panels on the roof provide enough power for us to store in batteries and use to light 11 bulbs in the house. The house incidentally has no fans let alone AC’s thanks to the cool terrace as well as thanks to the trees planted on the sides which enfold it in shade.
A well designed rooftop can provide all the water required for a house-hold, provide energy for cooking , lighting and water heating, provide food-grains and vegetables , enhance bio-diversity as well as absorb all the waste-stream from the house from the kitchen and bathroom / toilets and convert it to reuse .
This large beautiful well is close to Jakkur Tank in the Northern part of the city . The farmer draws 50,000 litres from the open well over a 12 hour time frame. Another 50,000 litres is drawn from a bore-well which is drilled inside the open well. This magnificent structure is about 50 years old. It is fed by the large Jakkur Lake with a 50 Hectare waterspread. The tank itself is designed to receive an eventual 10 million litres per day of treated waste water which should keep the lake full for the whole year. This well too will be full . Can we preserve and integrate the well into the water plans of the city ?
Harvesting Rainwater 