M. Murli Sharma, botanist, ecologist, water activist has become a widely cited example of household-scale rainwater harvesting and groundwater conservation in urban Telangana. The retired ICRISAT scientist — who has run his Secunderabad household entirely on harvested rainwater for three decades with an underground sump/tank of about 1–1.25 lakh litres capacity — speaks with Kalyan S Maramganti of Neo Science Hub on adapting the Marwari tanka to the urban roof, the economics of a lakh-litre tank, why Chennai succeeded where Hyderabad shrugged, and what he would build differently today.
Which traditional Marwari tanka practices did you retain in your 1995 home, and which did you change?
See, the tanka system as it was traditionally made — there were two kinds. One was the open-land tanka, meant for public or community use, often built along the roads of that time so that travellers passing by could use it. These captured water from open ground and collected it in a round, well-like tank.
The tanka made in houses was invariably in the chowk — the open courtyard, open to the sky. And it is not that these existed only in Marwar; they were in Gujarat, in Andhra Pradesh, in Tamil Nadu — everywhere, and outside India also. In Marwar, the tankas were in the chowk, and many a time, if the chowk was small, the tank was also small.
Now, coming to your question — in these urban houses, where is the open courtyard? There is only an RCC roof. So that is the variation. What I have done is this: in such houses, make an underground tank first, then put a reinforced concrete cover on that tank — and that cover becomes the floor of the house. In fact, we are sitting on that tanka right now. Its cover has become the floor of this room.
That is how we have adapted our conventional, traditional design to an urban house. I have done only that. I have not made any big new discovery. It is simply fitting our tradition to the requirement of the type of houses we build now.
Can you explain the design of your one-lakh-litre rainwater tank, its brick filter, and how you maintain it after thirty years?
The architect told me it should be structurally balanced — a term I did not know until he said it. And there was also the Vastu consideration we follow here: his perception was very clear that it had to be on the north-east side. As it happened, that was the side I was thinking of anyway, so there was no clash.
My house is not on RCC columns; it stands on a load-bearing foundation. So we decided to make the underground tank not from bricks but from granite stones. The tank is built of granite stone; the load-bearing walls of the house are brick. Ordinary cement flooring, the same as in the house, was laid inside the tank, and good-quality cement mortar was used for pointing the stones.
That is how we built it — and yes, it works well. In the name of maintenance, it really takes nothing. It needs some cleaning once a year, which I do myself. Other than that, actually nothing.
After three decades of drinking stored rainwater, what have you learned about its quality and safety? Have you noticed any changes over time?
The quality is consistent. Our area is not polluted, so I see no risk. My health — nothing has gone wrong. It is perfectly fine for us. I have not seen any change in the water; it is just as I expected.
And safety?
Safety is not a concern at all. We do not get acid rain here — that is a problem you might expect only in an area full of chemical industries. We have nothing of that kind here. No issue.
How much water does your family use daily, and how has rainwater harvesting saved you money compared to other sources?
Every day we may be using almost 500 litres for watering the plants — on all four sides and outside — and almost 500 litres for household consumption. So, nearly 1,000 litres a day.
On money — see, there are a few things. For living, there is a cost; you cannot apply very hard economics to that. But there is an indirect way of counting it. If I had to buy water by tanker, this tank gives me close to fifty tanker-loads of water free every year. And I would otherwise have needed a two-horsepower suction pump — the pumps of those days consumed a lot of electricity. We use no borewell at all, we pay no tanker costs, and we run only a one-fourth-horsepower pump to lift water to the overhead tank.
At one time I did the calculation — you can also work it out from those fifty free tanker-loads. By that arithmetic, I have already recovered the entire cost of constructing this building, only by conserving water. In just twenty years, you can recover the whole cost of your house construction if you conserve water like us.
What was the toughest drought or low-rainfall year you faced? Did your system ever come close to failing?
Since the time we built this house — no tough year. Let me put it this way: the city’s water requirement has been increasing, and every year the newspapers and TV will say “this year is tough.” But rainfall-wise, since we built this house, no year was tough. We have been getting above-normal rainfall.
I have been here forty-eight years. The maximum rain we received was in 1978 — close to 1,600 millimetres, double the normal. In the early nineties there was one year when we got only about 650 to 700 millimetres; deficit-wise, yes, that was the one deficit year. Otherwise, there is an increasing trend of rainfall here. The “tough year” is because the city’s population, industry, commerce and office establishments keep increasing — so the water requirement increases. That is all.
From your experience, why do some household rainwater harvesting systems fail?
See — among all those systems where people are doing what we do — conserving rainwater first in a structure, an underground tank or reservoir, pumping it to the overhead tank, using it in bathrooms, kitchen, garden, and sending the used water into a soak pit or the drain — I do not see a single case that has not worked. They are all successful; no question about it.
The soak pits, yes, they are working — the only thing is that they also need some care. If a fine layer accumulates on top, those stones should be removed, washed, and put back; then again it will be perfect. If we think these systems are completely zero-maintenance — no. Some work they need. We take some care of ourselves every day also; without that care we would not have a healthy life.
Now, in many cases the soak pits made by the government are not successful — but it is not the government’s fault, and not the fault of the department that built them. It is the fault of the colony residents. “I don’t want a soak pit near my house because I need to park my car there” — so whatever the government has made, they break it and start parking the car. The government made a soak pit for you; if you will not maintain it, then yes, there are troubles. But that is our making, not the fault of the system or the government.
Why has rainwater harvesting succeeded in Chennai but not in Hyderabad? What changes are needed?
Chennai suffered more than us — that is one reason. See, the act on trees and water conservation was passed first in Andhra Pradesh; Tamil Nadu passed theirs about six months after us. But because they were suffering badly, particularly in Chennai, the implementation there was more honest. Here, our approach to implementation was a chalta hai type of thing — lacklustre. They have been serious about it; we have not.
And again, the mindset: if by making one phone call and paying five hundred rupees I can get five thousand litres of water, then I don’t want to do anything else. If that is the mindset, then neither government nor God can help. That is the issue.
Although, yes — in that act I find something definitely unusual, because those who drafted it probably did not think very seriously. There is a clause offering a property-tax deduction if you comply. Even I do not qualify for it. Because along with water conservation, it demands eight or ten trees — in a small house like this! How can I put ten trees? No way — unless I want to bluff the system by putting a tree in a pot and saying, “Look sir, here is the tree.” If ten trees stood in this ground, their roots would uproot my house. There should have been better-drafted legislation, or an amendment can still be made. Otherwise I am very sure that not a single person has honestly received that property-tax deduction — because no one qualifies.
Did your home rainwater system grow from your scientific work at ICRISAT? And what inspires people more — data or practical example?
In my case — I come from the desert. So we know the value of water. You live in this colony; you might have seen how many people simply waste water, leaving the hose running to clean the portico instead of using a broom, or a bucket and mug. People have a tendency to waste, probably because the mindset formed that plenty is available — compared to my desert, it rains two and a half times more here. That mentality persists even though water has slowly, consistently, become scarce over the decades.
But the issue is our own awareness. If people are wasteful, what can the government do? The government is spending huge money on infrastructure to bring water from seven or eight different sources — the nearest maybe seventy or eighty kilometres away, the farthest 240 kilometres — and they lie at lower elevations while Hyderabad sits high, so the water must be pumped up, consuming enormous electricity. But as politics goes in our democracy, this is what happens. We put no value on water. We think: I am a voter, so the government or the Chief Minister will bring water to my house. That is a wrong mentality. And that is why the water bill is just 250 rupees. Some realistic cost should be charged; otherwise people remain wasteful.
And at the decision-making level, compared to the big irrigation projects, a city’s water requirement looks small — so the Chief Ministers and the big secretaries say, “It is small compared to the whole big thing; let it go.” So we have become used to cheap, subsidised water — and that is exactly why we do not know its value. That is the trouble.
With rainfall patterns changing due to climate change, what would you do differently if you built your system today?
Climate change is a very slow process — that is a fact. Fifteen thousand years ago, Antarctica did not have so much ice; there were areas with forests, with flora and fauna. England lay under ten metres of ice. That slow global warming melted the ice and raised the sea. What has accelerated it is our way of living — industrialisation, lakhs and crores of automobiles burning fossil fuel, and building houses that have turned our cities into heat islands. The city truly is a heat island: cement captures the day’s temperature, and after sunset the buildings dissipate all that energy, which is why city evenings are so uncomfortable.
But for my perception, here is what has actually changed locally: over the last sixty to seventy years there is an increasing trend of rainfall here. Publications seventy years ago recorded Hyderabad’s rainfall as 600 to 650 millimetres a year. Now it is about 850 millimetres — an increase of 200 millimetres. That is good for agriculture and good for me. But our requirement has also increased, and our wasteful habits have accelerated the damage. In the last twenty-eight to thirty years, I have not seen a single below-normal rainfall year.
And yet people complain the summer was the worst — how many borewells dried up this year in Hyderabad! Bores that had never failed have failed. Good lessons for us — but the trouble is, we do not learn. Mother does not have endless stuff that she will keep on giving and giving water. No. Unless we deposit in Mother’s bank, Mother will not give. In the name of climate change, Mother is actually giving more — and we are not conserving. That is our problem. The opportunity to conserve more water is available now; the systems are simple and cheap. If we are not doing it, the fault is ours.
In my own case — we built that stone tank. If I had to build again, I would build the house on reinforced cement concrete columns, and I would make the underground tank also in RCC. I think the quality would be better. In the kind I have made, many people face the trouble of roots getting in — because on the outer side of a stone or brick tank you cannot do very fine work, and roots damage such structures. And here on our Deccan plateau, stone and concrete are easily available and not very expensive, while brickwork has become costlier and granite has become unusually expensive. If I had to do it again, I would not use granite. I would make an RCC tank.
What message or policy would you recommend to make rainwater harvesting common practice across Indian cities?
First — and I am not saying a tricky thing — we must spread the message loud and clear that the government cannot always keep giving you free water. “Vote for me, I give you free water” — that is plain nonsense. It is there in our state also; it is just for votes, what else? Do not provide free water. If you want to give something else free, give it — but this free-water scheme is damaging the whole environment, the whole system, badly. Policy-wise, it has to go.
Second, the government must enforce the law that already exists. See — nobody who already has a house can build an underground tank like mine; the house is already standing. But every single household can still make a soak pit. Why is that not enforced? The law is there. Look at this colony — how many houses have one? Not many. There is a system of inspection, but it is not working; or if it existed in the past, someone pocketed the money and marked it “inspected.”
And does avoiding it save people money? No — it harms their own house. They end up spending more by buying tankers of third-class-quality water. The government’s tankers supply better water, but there are so many private players, and that water is definitely third class — no question about it. But who checks it? No one.
Now, one thing I do accept: while soak pits are extremely simple, making one involves many different players. Someone comes only for digging; then someone else must lift and transport the excavated earth; then the big three-to-five-inch stone — here we call it doddu kankara — is sold only by the full lorry-load, which one soak pit does not need, so unless you and your neighbour buy jointly, or pay the loading-auto three times the price, it is not practical. Then you need the smaller gravel as well. So either a whole colony contracts the work to one professional company — unloading half a load here, half a load there — or a government agency does it, which I do not think is possible, since most government work is anyway done by private contractors.
I know one such person — a very good man, Mr. Subash Reddy. He does excellent work; thousands of such soak pits he has made. He takes the whole contract and manages everything. That is the point I want to make: only the government’s danda will not solve the problem. It involves different materials, different players, and not everyone can manage them. And once you dig near a borewell, technical issues come — a pipe breaks, a drainage line passing through must be strengthened or replaced. It is not rocket science; these are simple things. But managing simple things is not easy — very often, managing simple things is the more difficult thing.
Still, the government can always do this: if you do not have a soak pit, we will disconnect your water supply. And if disconnecting water is a problem — then disconnect the electricity. The departments are different, but the government is one. If the government has the will, the government can enforce it. By carrot or by stick — but enforce it.
