A recent BBC report projected that Bengaluru will run out of water soon.
Yes, it was a superficial list of cities that already have water problem. It just pronounced the harsh verdict without any in-depth analysis of the factors involved. That’s like taking a casual look at an emaciated man and saying, “he is going to die soon”.
But in this case, all the x-rays and MRIs are only going to confirm the same verdict. Ignoring the problem is going to worsen the situation.
Let’s have a look at this complicated case, Munnabhai-style. He is bound to say, “Ae maamu! Tere Bangalore ki toh vaat lageli hai re!”
- The BWSSB puzzle
First let us unravel the mystery of just how much water is really supplied by BWSSB. Before that, let us understand how much water is needed.
If you do not reuse treated sewage for flush and gardening, you need 140 liter water every day. If you reuse treated sewage, you need only 90 liter fresh water every day. Let us assume that most of us do not have a dual plumbing system. So we 1.2 Crore Bangaloreans need about 21.7 tmcft fresh water.
Against this, BWSSB has 18 tmcft water, which it supplies to 50% (60 lakh) Bangaloreans. These BWSSB customers receive only 20-30% of their need.
In other words, with the available water, BWSSB should be able to meet 83% of our daily water need. Instead, it meets only 15% of our daily water needs.
This simply does not make any sense. The story about 50% loss reduced to 25% just does not hold. This calls for an in-depth spatial data analysis, including how equitable the distribution is.
- Our aquifers are drying up at an alarming rate!
Nearly half of our water comes from deep aquifers (located 1000 ft on average). Just a few years ago, we had many more aquifers at 200-300 ft, but they went dry rapidly. Even the present aquifers will surely dry up eventually, because they are not being recharged at all. Before they go completely dry, we will face the dangers of heavy metals. Apart from that, nearly half of the present-day borewells are contaminated, and are unfit for human consumption. So even if they do have water, they must not be used. But BWSSB has no plan to test all borewells and ensure that only the healthy borewells are used.
- Rainwater recharge may not be a solution!
Some people have proposed rainwater harvesting as a solution. Sure, there are anecdotes of open wells filled till the brim. But these examples are from villages or vast gardens, where the catchment area is vast, and wells are few. And even those wells are used frugally. The same model may not serve Bengaluru, because the harvesting is minimal and draw is heavy.
So how much can we recharge at best?
Let’s assume the median apartment size is 1500 sq ft (150 sqm), and average 10-floors apartment. Assuming 900mm rain, the terrace gets (150 sq m*0.9 m)= 135 kl. This is divided into 10 floors, which amounts to 13.5 kl/household. This is sufficient to last for 13.5/0.7=19 days (not even 3 weeks).
Thus, even if we do rainwater harvesting, we draw water for 52 weeks in a year, and recharge for three weeks.
Further, only a fraction of this water will actually reach the aquifers. It is unrealistic to hope that our agencies will be able to achieve any rainwater harvesting goals in the rest of the area.
- The dying lakes are not given a chance!
Our lake system can be likened to a patient who has multiple organ failure. Our lakes are polluted because multiple agencies are dysfunctional.
This situation is not even acknowledged, far less corrected. Thus we cannot hope for a miracle, and revival of the lakes.
Also, to revive a lake, all the sewage coming to each lake has to be intercepted and treated with a local Sewage Treatment Plant (STP) and wetland. The wetland must be large enough to retain the incoming sewage for five days.
But BDA and BBMP have themselves destroyed the natural wetlands to convert them into layouts, bus stops, etc.
It is possible to get the same function with constructed wetlands, but the only way to construct these wetlands is to reclaim encroachments on government land.
Just the Bellandur-Varthur lake system has 96 lakes. Thus we need almost an equal number of small STPs and wetlands to take care of these lakes.
But BWSSB has not located their STPs strategically to revive any of these 96 upstream lakes. There are no wetlands planned for these lakes, either. So the groundwater recharging scenario is not going to change.
- The rainwater drains are doomed to carry sewage because of faulty policy
We have drains of different sizes, from the road-side drains to the Raja Kaluves. These are strictly meant to carry rainwater to replenish the lakes.
Practically, any large apartment must discard at least half of its treated sewage. But KSPCB follows an archaic “zero discharge policy”, under which each apartment complex must consume the treated sewage within its campus. So BWSSB does not no provide any pipeline for treated sewage discharge. Thus large apartments end up discharging their treated sewage in the drains.
On top of this, people who do not have BWSSB connection dump their raw sewage in the drains. This is why all drains in Bangalore carry a mix of raw and treated sewage. This nutrition-rich sewage reaching the lakes causes wild growth of macrophytes and algae. Finally this leads to fish kill.
- Are the “good recovered lakes” a ray of hope?
Some people point at the good examples, where citizen intervention resulted in recovery of some lakes, which went on to become showcases. But these cases need not be a good example of anything.
First of all, these lakes were recovered by citizens, by fighting off the administration, which by itself is a matter of shame; and let us hope that this does not set a lesson for the public.
Secondly, in all such cases, the sewage of the area was bypassed. The lake is the lowest depression in its area. Thus it is bound to receive any sewage generated in the area. But bypassing the sewage makes the downstream people suffer.
- Reuse of sewage is the real answer, but never attempted!
We think nothing of throwing away 1400 million liters of sewage every day. Just 30 km downstream, this sewage is treated as normal water. More than 10 towns and cities in Tamil Nadu use this water without any aversion.
But we are still hung up on the idea of the mythical holy river “Cauvery”. Should we not take a lesson from this?
Globally, areas with water shortage are recycling their sewage. Even WHO has guideline on two different types of sewage reuse:
- DPR (Direct Potable Resuse) – Reclaimed sewage is used directly
- IPR (Indirect Potable Resuse) – Reclaimed sewage is mixed with “normal” water and then used.
There are methods to inject the reclaimed sewage into groundwater. But we are not availing of this single opportunity.
So how to prove BBC wrong?
Well, here’s what Munnabhai would recommend:
- Set right the dysfunctional agencies urgently
- Re-plan the revival of each lake, with its own STP and wetland.
- Set up local sewage reuse (DPR or IPR)
This article was first published on Citizen Matters and has been republished here with permission. The original article can be viewed here.