Archive for May, 2010


Nitrates in groundwater

May 29, 2010


Every layout must have a sewage treatment plant


Nitrate contamination through sewage is the single largest polluter of groundwater in Bangalore

What scientific age?: Uncollected and untreated sewage ends up in our lakes and rivers and also in our groundwater

Many cities in India can be smelt before they can be seen, if you arrive by train or bus. The overwhelming presence of untreated sewage flowing in stormwater drains or in gutters and collecting pools in surface water bodies is not only un-aesthetic but unhealthy too. This uncollected and untreated sewage ends up in our lakes and rivers and also in our groundwater. Nitrate contamination through sewage is the single largest polluter of groundwater in Bangalore. It is also good to remember that uncollected and untreated domestic sewage is the largest volume of pollutant in a city. The numbers reach over 400 million litres per day in Bangalore.

What should be done?

Cities must invest in a 100 per cent collection and treatment of wastewater. Decentralised systems are emerging that can do so at smaller neighbourhood levels. These decentralised sewage treatment plants can be linked to the nearest park or tank and the tertiary treated sewage used to fill the tanks after a small wetland-based biological process. These will not only keep our tanks full but also replenish groundwater in the surrounding areas.

Layouts of even 200 households can set up treatment plants for waste water and reuse it for non-potable purpose within the layout. Individual apartments are already demonstrating that this is possible and even individual households can treat grey water and black water separately for reuse. A household-centred wastewater treatment approach is what cities of the future are looking at.


In Bangalore, an abysmal Rs. 15 is paid as sewage cess by a household consuming up to 25,000 litres every month. This works out to 50 paise a day. Even beggars are known to have rejected such a sum. How can an institution ever hope to maintain a system and improve infrastructure for collection and treatment of sewage? A realistic hike in price is a must for the city to manage wastewater. The “polluter pays” principle must apply to households as well.

Typically cities tend to invest in fresh water supply systems which tend to bring more water to the city. This fresh water is consumed, turns to wastewater and then, because the collection and treatment mechanism is not in place, becomes a pollutant. The fresh water available in the city as surface water and groundwater now gets polluted, demanding more fresh water from even more distant sources. A paradigm called “fouling the nest.”

An open well can deliver the cheapest water and the most energy-efficient water provided the aquifer is kept full and not allowed to be contaminated by sewage.

Bangalore has set up some excellent wastewater treatment plants at Cubbon Park and Lalbagh. These are state-of-the art units which need to be replicated quickly and in more number of places. There is another excellent wastewater treatment plant in Madivala tank in South Bangalore, which enables treated water to be used to keep the tank full. These need to be rolled out for all tanks.

Only in collecting and treating wastewater and linking it with the protection of our surface and groundwater resources will we ensure sustainable waters for our cities. In this approach lies water wisdom.

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The Namma Bangalore awards

May 27, 2010

The Rainwater Club was recognised in this peoples award from Bengaluru.


On sustainable sanitation

May 25, 2010


Study this plant fertilizer – Using sanitation for crops


Eco-san creates toilet systems which separate solids and liquids at source and treats them before they are applied on soil as a nutrient

As sanitation involves water, this week’s ‘Waterwise’ series brings you details on how the nutrients in human wastes can be converted into manure for growing greenery.

Eco-san is a shortened term used to describe Ecological sanitation, a system of sanitation which seeks to handle human wastes safely and in a hygienic manner without causing pollution and using the nutrient value contained in the waste for growing plants.

It is well recognised that bad sanitation systems not only cause health problems but also pollute the environment dramatically. In Bangalore, ground water to depths of 400 feet has been polluted with nitrates, according to a Department of Mines and Geology study. Up to 70 per cent of the wells studied had excess nitrate in them.

A study of several wells in the Koramangala and Challaghatta valleys of Bangalore by the State Pollution Control Board also reported severe contamination.

All this pollution came from domestic sewage and bad sewage systems. This also has the effect of rendering the abundantly available groundwater unfit for any use, thus creating a shortage of water.

Eco-san tries to address the situation by creating toilet systems which separate solids and liquids at source, use urine as a fertilizer for plants and compost the faeces to remove pathogens before being applied on soil as a nutrient.

Ecosan toilet

The Indian style Ecosan pan is designed with three openings. One for the urine, one for the solids and one for ablution purpose. All three are disposed of in different ways. The urine can be collected in barrels and then used as a fertilizer or it can be led into a vegetable patch directly. This applies to ablution water too.

The solids are composted in situ by designing two boxes. When one box is full the pan is shifted to the other box.

After every use of the toilet the solids are covered with ash or sawdust or any organic material.

This ensures no smell. This pan is being made in Bangalore by N-Fibro Systems in Rajajinagar.

The Eco-san movement has rapidly spread and taken root in many parts of the world.

In India too, pioneers such as Paul Calvert ( have demonstrated its application in high water table areas of Kerala, Tamil Nadu and Karnataka and many other places.

These applications have mostly been in rural places with a few exceptions.

In an urban context, in a school in Dodballapur (population 100,000), an eco-san toilet has been built by several partners led by the group Waste wise.

The school children have received training in its correct use.

Farmers are using the urine generated for applications in maize, banana, lemon and papaya plantations.

Western system

Western-style Ecosan WCs are yet to come to India in a significant way but are available in countries such as Mexico and South Africa. As time goes they should become available here too.

Through a combined strategy of application and construction, communication, research and finding, funding urban eco-san can be pushed as one solution to the critical problem of groundwater contamination, especially through nitrates, in cities such as Bangalore.


A Water Bill revisited

May 20, 2010

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I am connected to the city mains for my water supply as are you I guess if you are in urban India.The bill comes to me once a month. I do not even bother looking at it and pay it because it is that small, until now that is. While travelling in a bus to Mysore (btw I live in Bangalore) and the battery on my mobile phone dead, the only option was reading to amuse myself. I dived into my purse to get some money for a magazine and came out with an old water bill. Read the magazine- not interesting- then started to look at the water bill out of sheer boredom.

Now this was hugely interesting. Let us see what it tells me about the water supply provider in our fair city, Bangalore.

Firstly that I get a bill looks like I have to pay on volumetric consumption. Ah ha , not many cities do that. They collect

a flat tariff or charge it on the property tax. Experts agree that volumetric tariff is good because you pay for what you get.

You are rewarded for good behaviour i.e. less consumption and punished for over consuming. Great beginning for Bangalore’s water supply.

The reverse side of the bill first if you please. It talks about a sanitary cess. Hmmmm.. I pay for my sewage too, very funny. I flip the bill around, hey I consume less than 25,000 litres every month, just 7000 litres this month and so i pay a flat sum of Rs 15 for all the shi… that I send into the drain. Pretty cheap huh. That’s 50 paise a day for the much to be collected, coveyed through pipes and then treated. No way. That’s why the stuff is flowing in storm water drains and all around. C’mon BWSSB get reasonable ; and charge me for the whole shebang. Polluter pays and all that you know.

Then I come down the bill, what’s this? A differential slab for my water bill. If i consume less than 8000 litres I pay at Rs 6 / a kilolitre. So now that i have consumed 7  kilolitres my bill should be 6 x 7 = Rs 42 ah.. ha.. a right royal sum. Hey but these guys charge me Rs 48/-? How come? That is a minimum then, so I harvest rain, use it and consume less but i pay Rs 48 /- nonetheless.Might as wellhave consumed the 1000 litres . Would’ve been free for me. .. and where is the incentive for harvesting rain? Let it be.

But lookat, the guys in the hotel business pay something called non domestic rates which is high and the industrial consumers are rogered , they pay Rs 60/= on top of which a cess of 20% thats Rs 72/- a kilo litre. No wonder they drift to a bore well or a private water tanker. That costs a lot less.

But whats this? A bore well cess of Rs 50 /- a month per house . Thank god I do not have a bore well in my house. So these guys must have a count of the number of bore wells in the city or at-least wherever they have extended their connection. very interesting. Now if they could put a meter to the bore wells a we would know how much groundwater is being consumed in this city. Got to work on that with these guys.

There is message to conserve water. Are these people serious. In Kannada there is a dire warning not to employ child labour. Wonderful look at the social concern of these guys. but wait no ‘lifeline ‘ water for the poor. 6000 litres per month per family free. Like in South Africa that would have been good.

Now the front side of the bill. The bottom line says if connection is not made by due date then disconnection process will be initiated. Hey what was the last date for payment? 27/09/2006 I see on the top right side. Good that I have paid

on time. These guys are also gentle. They at least don’t say that they will disconnect. Only begin a process.

Hopefully there will be a notice. I generally am late for everything so guys like me deserve a notice. Is there a fine or a

late payment fee? hmmm… nothing about that. Got to find out more from the sub division I guess. Which is it? N3 says

the bill. Informative. What does N-33 and RR no. and consumer i.d mean. ? I’m a number and I know what that means?

I want my UID.

There is a meter reading date and last date for paymetnt is 15 days from that day. Great, 15 days. but do these guys send me the bill on the date of the reading itself? Gotta check sometime. Then there is the water charge.. that I understand and a meter charge of Rs 10/-? Hey I pay for the meter. The meter costs about Rs 600 /- methinks. Do these guys stop after 60 months and they have collected Rs 600/- Nope . I built my house in 1994 and this is circa 2010 and yet the meter charge goes on.Must be for the meter reading methinks. Oh alright about that one then.

What is this S.C for bore wells? Sanitary charge looks like. If I use water from a bore well obviously the sewage goes to the system for which these guys are responsible.

So a sanitary cess on bore well water use. Rs 50/- a month too. If only these people could put a meter on the bore well.

they would have known exactly how much sewage is entering the system from bore well water not to mention how much bore wells are used in the city. Bangalore is one of the first city in India to do this. Great going guys. Hey there is an arrears of Rs 4/ What happened? I didn’t pay 4 bucks to these guys last month? .. and they keep tabs on that. Wonderful.

I see that I can pay my bill 24 hours at their kiosks. That is great. I get water 2 hours every alternate day but these guys

collect money 24/7.  Must be a World Bank plot. That Paul Wolfinsheepsclothing and his girfriend. Grr… Must rally with

the anti privatisation and anti world bank guys next time. Remind me to take out my khadi clothes and jhola.

Finally there is some kind of bar code at this end. Modernity and swiping machines i guess.

Now how many cities in India have this kind of a bill and this kind of a water supply? Would be good to compile.

Guys and girls please help and send me your water bills. Just a copy will do from anytown India. We’ll discuss that in the

coming blogs.. that is if you are not fed up with this one :)


The 4 taps approach- to sustainable urban water management

May 16, 2010


The ‘four taps’ approach


Bangalore can learn from Singapore, which obtains water from four different sources

Needed: More of such water recycling plants

As the city experiences water scarcity in some parts and launches a drive to drill new borewells to temporarily overcome the shortage it would be wise to remember the “4 taps approach” of Singapore. It famously developed and implemented rainwater catchment and storage in reservoirs, got water from Malaysia, recycled waste-water and desalinated water as its multiple sources of water.

Bangalore too can develop water from the Cauvery/Arkavathy, groundwater, rainwater and recycled waste-water as its “four taps.” This is already happening; however, a systematic approach will provide stewardship for all ‘four’ taps.

The solution is also scale independent, hence it can be included as a strategy by individual buildings, apartments, layouts, institutional buildings et al.

Consider the College of Engineering on Mysore Road. With a large campus and huge buildings, it requires both piped water and ground water. It invested in a rainwater tank and recharge structure to capture all the rain from the massive rooftops and built a huge sump to store it. In April itself , thanks to the showers, the tank filled up three times and provided the much needed supplementary water. Excess water from the sump will recharge the groundwater aquifers and keep the borewells charged.

Good impact

The institution will now actively consider waste- water recycling as the fourth source of non-potable water use. The single largest benefit is the demonstration effect for the students on stewardship of the environment.

Consider also this layout on Sarjapur Road to the east of the city which, when faced with water scarcity, invested in rainwater harvesting and groundwater recharge. The waste-water treatment plant has been made more efficient in operation and the treated waste-water is used for all landscape requirements. It now has borewells, rainwater and treated waste-water and waits for the Cauvery line to top up requirements.

With the mandatory rule for rainwater harvesting, every building in Bangalore now has a chance to augment its Cauvery supply or borewell-based supply with rainwater. It is a matter of time when greywater reuse too will come in, given the overall shortage of water.

With an overall shortage of water, wisdom lies in reducing demand to the optimum, not wasting water, and adopting the “four taps” approach. That is the way towards sustainability and water wisdom.


Recharge wells and their role in aquifer management

May 16, 2010


The importance of recharge wells


At the last count, the Bangalore Water Supply and Sewerage Board had listed nearly 110,000 borewells as having been drilled in the city. At least another 110,000 may exist because the BWSSB counts only those borewells where it has provided a water connection.

With such huge numbers, an average pumping of 2,000 litres per day per borewell means well over 400 million litres per day is being sucked out from the aquifers.

The groundwater is topped up whenever it rains. In a year, six to 10 per cent of the rainfall goes below one metre and recharges the aquifer. In Bangalore this would mean that the natural recharge would be about 200 to 250 million litres equivalent.

From tank beds, the average recharge rate is 10 mm to 20 mm per square metre per day. This means about 10 to 20 litres of water recharges the aquifer every day for every square metre of tank area when the tank is full and de-silted.

To recharge the aquifer and to reduce the overdraft of groundwater we need recharge wells. Typically, in the Bangalore context, they are three ft. in diameter and about 20 ft. deep. Recharge rates vary depending on the thickness of the weathered rock overburden and the nature of it. On the IIM premises in South Bangalore recharge rate of 1,000 litres per hour has been observed in recharge wells. In North Bangalore’s Vidyaranyapura, similar rates have been observed in wells which are just 12 ft. deep, probably due to the lateritic overburden.

Existing wells in several parts of the city which have been recharged also show such rates of recharge.

Compare the recharge rate of a tank at 20 litres per day per square metre to that of a good recharge well which is 24,000 litres per day and the difference becomes stark. Recharge wells outperform tanks by a factor of 1200.

If two lakh recharge wells — one for each borewell in the city — pick rainwater from 200 square metres of roof area and recharge the aquifers, close to 32,000 million litres of water will reach the aquifers annually.

How is a recharge well made?

A pit of four ft. diameter is dug till the depth required, and three ft. diameter precast concrete rings are lowered and placed one on top of each other. The sides are then packed with gravel as each ring is placed. The well is covered on top by a steel grill or a concrete slab for security and safety. Clean storm water or rooftop rainwater is then led into the well to recharge it during the rains.


Rain in chain

May 8, 2010


Go in for a stylish RWH system


It can add to the visual appeal of a building

Beautiful: Rainwater flows through the chains into a sand filter

Rainwater harvesting has become mandatory in Bangalore. The rule is relatively simple: create storage or recharge at the rate of 20 litres for every square metre of roof area. For the non-roof area of a site create storage or recharge at 10 litres per square metre of such area.

A rooftop rainwater harvesting system consists of a catchment, which is the roof itself; a conveyance system which includes rainwater gutters in the case of a sloping roof and pipes in case of a flat roof; filtration system to keep organic particles and dust out; and, finally, a storage system or a recharge system.

Storage systems can be either rain barrels or sumps. Recharge systems are usually recharge wells. A concern of many is the visual aspect of rainwater harvesting.

Pipes hanging or moving about hardly look pleasing. If designed well, rainwater harvesting systems can add to the visual appeal of a building.

Like a waterfall

In Gowri and Harish’s beautiful earth home, the rainwater harvesting system has been designed with aesthetics in mind. Aluminum gutters collect rainwater from a sloping tiled roof. They convey the rainwater to a downspout where a few strands of hanging chains are placed. Rainwater flows on the hanging chains and adheres to them due to surface tension. During rains the feel and the sound is that of a waterfall. A stone pot camouflages a sand filter. The rain is filtered here and a concealed pipe then takes it into an underground sump tank.

The functionality of the system is not lost and close to 100,000 litres of rainwater is harvested here. At the same time the visual appearance of the building is enhanced as is the curiosity impulse. People ask and are then better informed of the rainwater system.