CII has started the Karnataka State Water Network and has identified water sustainability zones in Bengaluru.
With a desultory monsoon drawing to a close, drought grips many parts of India including Maharashtra and Karnataka. The impact of the drought is primarily on agriculture in the rural areas but its impact is also on urban areas and on industry, as water as a resource becomes in short supply. While mitigation measures are many and relief reaches out to farmers, cities too need to think on how to manage drought in an era of climate change.
One way to manage large urban areas is to think about smaller watersheds within and manage them as water sustainability zones.
This is precisely the objective of the CII in Karnataka which has started the Karnataka State Water Network (www.kswn.in) to bring together industry, community and government to plan and manage water sustainability zones within Bengaluru.
The zones chosen by the industry champion include:
- Electronics City
- the International Airport area,
- the area around Bharat Electronics
- the area around Sarjapur Road
- Peenya Industrial Area
and finally a more generic area which includes the lakes of Bengaluru.
A platform is now created where communities can usually come around lakes and address the major water challenges occurring around managing waste-water, restoring groundwater, helping protect and preserve a lake, supplying drinking water and other such issues.
That the dialogue has begun between various stakeholders is a starting point. Implementation ideas are also being drawn up which will result in action on the ground which will make sure that the social and ecological aspects of water management are included as much as the economic aspect of water.
Best practices of industries within their fence are being shared and broader understanding of challenges beyond the fence is also being understood.
This means that competitive use of water is giving way to understanding what it means to enter a domain of sharing water.
Critical technical issues such as the treatment of industrial effluents, the management of waste-water, the understanding of aquifers and groundwater, demand management and recycling and reuse of water are all being taken up by the various sustainability zones and their champions.
Industry in turn learns how societies and government perceive and deal with the commons and what the challenges involved are.
This partnership approach is one way of managing water as a resource in an era of climate change, and is water wisdom.
Cities too need to think on how to manage drought in an era of climate change
Exploring alternatives is mandatory if we want a greener future.
How did people get hot water before the electric geyser was introduced? They simply heated it with firewood and even today it is the most common approach in all rural areas. How do we heat water for drinking? The burning gas stove ensures we get healthy warm water to drink. The above examples are only to say that heating is not solely dependent upon electric geysers.
The idea of wood fired hot water still continues, often called in Karnataka as Gujarath boiler, an idea that possibly originated from industrial boilers. It consists of an oven with a small mouth and a water pipe with cold water inlet at the bottom. This water pipe rises upwards, initially with wider diameter like 12 inches and later narrowing, reaching up to the last terrace without any other joints. From this highest point, the pipe comes down to the bathrooms as may be needed, creating a completely sealed pipe system. It is important that the system works like one unit, with no openings except for one inlet and outlets.
Any combustible material like home garden wastes, coconut peels, dried twigs, leaves, paper and old trash, most of which can be found in any city, can be used as a replacement for firewood in the oven. The cold water filled in the pipe gets heated up, rises up thanks to differential weight of cold and hot water and reaches the terrace level while fresh cold water flows to get heated up. From the terrace level, the hot water flows down into bath taps by gravity. As we use the hot water, the outflow is replaced by fresh inflow of water and after a few people taking bath, there may be no more hot water left, suggesting we fire it again. Gujarat boilers are among the easy solutions providing life-long service with a water column, simple operation and short firing period with very little running costs.
Cooking gas cylinders have revolutionised not only the kitchen but also the bathroom. Popularly called as gas geysers, these battery operated geysers are very economical and convenient. Just like in a gas stove, an inbuilt lighter starts a fire inside the geyser, heating up the water in the small storage tank inside to provide hot water instantly. As hot water flows out, cold water gets in for further heating.
There have been rumours about them as being unsafe which has no proof, especially when the gas cylinder is kept outside the house. Operationally, it’s same as the kitchen stove, but for the periodic need to replace batteries which light up the spark. The unsafe ones are the water drums with exposed electric coil immersed inside to heat water.
With our modern lifestyle already in place, there are no single and perfect solutions to our needs today. Exploring the alternatives is hence mandatory if we have look for greener futures.
Today most tanks are made from synthetic plastics with high embodied energy, produce much waste in production, cannot be cleaned easily and heat up the water during the summer afternoon just when we need cool water. The traditional brick water tanks have solid concrete roof with all the strength and security associated with concrete, which are not required for water tanks. We lift up the tank level at extra cost, with no other benefit but the extra height. Often tanks are so small that frequent pumping up become a necessity or they are too large with stagnant water. In many such ways, we are not getting the best from overhead tanks.
For a small family of four, we do not need more than two days’ supply of approximately 1,500 litres atop the house. The water consumption per person per day is around 150 to 200 litres, so in case of large storage capacity, daily replacement will be small, leaving the old water in the tank. Instead of the RCC roof top, we can have a metal sheet lid framed in M.S. angles that can be lifted up like a car bonnet. This drastically reduces the cost, makes the job simple and enables anyone to get into the tank to clean it. Most people do not periodically clean the tank, for it’s a cumbersome procedure, so the lid concept eases it out.
If the tank is placed in the corner of the building, we get two edge supports and can save on structural cost with a diagonal beam. To get the water pressure for solar water heaters, we need a minimum height of 6 ft., which can be further raised to get 7 ft. underneath the tank. By a small extension of the tank slab, we can actually get a small room underneath for storage, stay, study, wash, pressure pumps or as may be needed. On the cost front, this room would come at a nominal extra cost, but contribute to varied activities on the terrace.
Taking fewer large diameter pipes and then branching them off into multiple taps instead of taking a separate outlet pipe for every tap is another measure to save on plumbing. Let all pipe connections be accessible for future inspection. Replacing G.I. pipes by the new generation pipes has decreased the need for repairs.
Being a manufactured and marketed product, the PVC tanks have surged ahead of traditional brick tanks in popularity, though they come with numerous problems. The only possible problem with brick tanks is seepage due to bad workmanship, which can be mitigated by some attention. Plastering the inside with chicken mesh eliminates the seepage, while anti-fungus paint keeps it clean. Water in a brick tank stays cool and is any day healthier.
What is the nightmare for designers as a house nears completion? One answer is overhead water tanks! If they happened to be visible from the road, no design seems to be convincing enough. Possibly so, most house owners do not bother about how it appears, leaving it as a sore thumb rising from a beautifully designed house.
Besides the matter of aesthetics, the very idea of high-level water tanks is an energy consuming proposal. The electricity required to pump water from low levels to cities at higher plateau, then take it from ground level treatment plants to large neighbourhood water tanks demands a good share of the city electricity supply. Though the supply to individual sites is on gravity flow, imagine each building again pumping it up – the whole exercise appears to be against the natural principles of water flow. Though the story of reaching water from a far-off river to the house kitchen is exciting as a civilisation achievement, it is also a story of battling against nature, consuming resources.
Many cities around the world are not dotted with water tanks forming their skylines, yet get day long water supply. From the treatment plants or a nearby surface level water sump, water is pumped continuously such that the houses need neither underground sump nor overhead tank. Just turn the tap on to get water anytime. It has been studied that such an arrangement does not necessarily increase water consumption, makes the pipes last longer avoiding the dry and wet conditions, avoids duplicating storage at every level keeping the final supply fresh, and saves lot of money otherwise spent by individual families. Above all, it negates the illogic of pumping water up the sky twice, against gravity.
Direct pumping is possible at the house level also with pumps connected from the sump to outlets. Whenever we turn a tap on, the pump automatically starts pumping water and stops when we close the tap. This measure avoids the need for an overhead tank and reduces the overall running length of pipes, offering monetary savings. Of course there should be regular power to ensure pumping at any time.
Inadequacy of supply
The present approach of having tall and large water tanks supplying water for a few hours to a large area means inadequacy of supply by gravity flow, pumping as a necessity, provision for sump with tank and longer lengths of pipes with pressure loss. One alternative lies in smaller water tanks spread over smaller areas to ensure full day water flow by gravity such that no house needs to build either a sump or a tank. When we feel the scarcity of water we tend to store it, only to use it later carelessly, but an assurance of regular supply automatically regulates the consumption as well. There is no proof to claim that longer supply means greater consumption, for everyday we all need water only for specific purposes, hence only in specific quantities.
Ask any engineer contractor to list areas of concern and we are almost sure to find water seepage and terrace water-proofing to be among the top. From the very local solutions like mud layer poured with lime slurry, a traditional cost-effective solution, to the latest research on chemical-based methods have all been explored, yet no one idea stands out as ‘the’ solution. Possibly, we cannot list varied eco-friendly options here, but some cost-effective ideas exist and are in practice.
By far, the most cost-effective method appears to be treating the concrete roof on the same evening of concreting, when it is still not hard set. Thin slurry with one part cement, two part fine grain river sand and ample water to create the flow condition is poured on the top of the freshly cast roof. Then, starting at one end, the masons will work backwards, gently levelling and pressing the slurry into the concrete, filling its micro pores; wiping out the step marks and such other undulations using a square, flat, handled trowel. This slurry should become an integral part of the roof while the concrete is still being soft and ensure that the top layer becomes impervious. Water-proofing admixtures in liquid form can be added to the slurry to get better quality. Normally, the top surface gets finished with thread lines to stop any possible crack from developing across the surface.
While this top surface would survive most climatic conditions, topping the terrace with weather proof course (WPC) tiles has many advantages, despite the additional costs. The terrace is cleaned, applied with slurry mix of 1:2 and surface made rough by sweeping it with broom stick. A mortar mix of 1:4 is applied on top, as if we are plastering the surface, and the thin WPC tiles are fixed with 2 to 3 mm gap in between. The WPC tiles are made of burnt clay with two surfaces and small holes in between. Normally, these tiles are broken into two parts, and laid with the smooth surface on top. Water-proofing compounds are not required at this stage, though there are contractors who prefer using them with the mortar. The WPC layer protects the concrete surface from sun, rain and wind, giving it a longer life. The terrace becomes more usable due to the good flooring.
Many companies have been promoting methods and corresponding products of their own towards effective terrace finish. Most of them rely upon chemicals, polyurethane coatings and admixtures, hence tend to have a limited life span, though they guarantee the surface until then.
Every terrace solution comes with its own advantages and disadvantages. The practice of terrace tiles may not go well with heavy rainfall areas, unless quality of workmanship is achieved. In such cases, the simple method of plaster on the same day works better. In hot, dry climatic zones, this method may heat up the interiors more, the top being just a dense concrete layer. As such, it is important to seek local solutions to the terrace.
Defective workmanship may not be visible until the ingress of water corrodes the steel rods inside the concrete roof.
The possible heat gain, finish for cool roof, opportunities for rainwater harvesting, temporary tents for family events, joy of terrace gardening, space for meditation, party zone, dehydrating food items, roof-top pavilion – this list can go on as per the family lifestyle.
It is curious that most of us fail to realise the full potential of the terrace and even if we intend to utilise it in some ways, neglect the other potential issues. More so when we design specifically with eco-friendly intentions, there are dangers of some common sense issues being ignored.
In a majority of the cases, roof slopes for rainwater drainage is planned after constructing the terrace, which ideally needs to be planned earlier.
In the absence of this, we often find outside terrace levels going higher than the threshold of door to terrace, because of the required water-proof layer outside. Of course, we can raise the threshold levels to stop water from getting into the house.
However, slopes have to be best aligned to get the minimum number of roof drain pipes which should converge into the rain filters at ground level at the shortest distance.
These pipes cannot cut across openings in the wall, preferably not in the front elevation, and be conveniently accessible for future inspections, if ever required.
Parapet walls can take metal rings to support future temporary roofs, shamianas and tents for small events. These, if felt needed, have to be well secured into the wall in advance. Also, it is possible to have light fixtures fitted into the wall to enable greater use of terrace at nights, but if the lifestyle does not demand them, it is better to avoid them. Many parapet walls have cracked due to the rusting of cheap quality ring and light fixture supports.
Among the common areas of concern has been the placing of solar heater, metal stairs and such others, where water proofing the point of fixing is very important. Defective workmanship may not be visible until the ingress of water corrodes the steel rods inside the concrete roof.
Today a range of methods are available for water proofing the terrace, but that would need a separate discussion. That aside, it is easy to list half-a-dozen functional possibilities with the terrace, all of which cannot be managed simultaneously.
Selecting the specific activities is the first step towards designing the terrace and finishing it appropriately. Though both rainwater harvesting and terrace vegetable gardening are possibilities towards eco-friendly living, managing both together is not easy.
Likewise, a small house terrace filled with skylights keeps the house bright, but reduces terrace area for activities. Getting a building done is increasingly becoming a matter of choice than merely having options.
Unless we speed up our efforts towards water conservation and judicious consumption, the problem is bound to increase.
It is good to see rain water being saved and used in urban areas on a wider scale nowadays and the resistance towards its storage reducing in the rural areas. Also, in many urban areas, rainwater harvesting is compulsory. However, this simple solution to the water crisis does not appear to have kept pace with the increasing crisis. As such unless we speed up our efforts towards water conservation and judicious consumption, the problem is bound to increase.
Among the basic causes, many city residents are apprehensive and hesitate to use it for daily needs like cooking or bathing, despite all that has been covered in the media about water harvesting as a larger proposal.
Many people collect the raw water from roof tops and let it percolate within their site. Some store the treated water in a sump for gardening, car wash and such allied purposes. Ideally we should be collecting the filtered water in a sump, pump it up to the terrace water tank otherwise done for public water supply and use it for all building and living needs. Only then we are saving the rain water to supplement daily needs. The rain water is perfectly suited for such total use.
There are a few systems to filter the water such as pop-up filters fitted within the pipes; gravel, sand and charcoal beds; and cloth filters. Let the water be filtered by the chosen system and flow into the storage sump which can be placed next to the public water sump.
Many people have installed two sets of pumps and pipes, spending much money. A single mono-block pump with single delivery pipe to the overhead tank is adequate. The pump can easily be fitted within the setback area.
There can be two suction pipes with gate valves, one fitted to public water and the other to the rain water tank. To pump up water from public supply, we need to open the valve of that sump and keep the rain water pipe closed.
When it rains and water collects, open the rain sump valve and close the public supply sump valve. It is important to keep pumping up the rain water whenever it fills the sump to maximise the benefits of harvesting.
Considering that the rain water is free, we can construct it to any volume as our funding may permit, but it is safer to maintain a minimum of 6,000 litres.
In cities with tanker water supply that can be ordered by phone, the tankers come with 6,000 litres and they would fill only one sump tank. In case of grey water tanks, they need not be placed close to the rain sumps, since no pump or pipes can be shared between the two.
It is fair on people to feel that managing both public and rain water is a difficult logistics, but if we realise how simple it is, it is our duty to manage it.
Instead of a blind practice, the frequency of municipal water supply and family size should together decide the ideal volume of storage required, to avoid both dead investment and unhealthy water.
What has a water storage sump got to do with an eco-friendly approach? If you think they are unrelated, you are in for a surprise. It is that grey area most house owners do not think about and builders simply follow a routine without ever wondering about the right practice. The fear of water scarcity in cities like Bangalore adds fuel to the fire with people building larger and larger sumps, spending much money on them. The idea of sump impacts water consumption, construction costs, water stagnation, setback space utilisation and such other indicators of a green home.
We all know that stored water does not stay fresh for too long, a point to reckon with while planning capacity of idle storage in sumps and tanks together. As per survey data, urban dwellers use 150 to 200 litres per day per person, so a family of five needs around 750 to 1,000 litres of water every day. This figure covers all tasks including drinking, cooking, cleaning, bathing, vehicle washing, gardening and occasional extra use due to guests or events. There are many families living with less consumption by avoiding car wash, lawns, high flow fixtures, large built-up area, hardy plants or activities in flowing water. However it is safe to assume the average consumption for size calculations.
How it works
If the city water supply comes every alternative day and we have an overhead tank for 2,000 litres and a sump for 5,000 litres, in every refill less than 2,000 litres out of 7,000 litres gets replaced. Over time, there will be more of old stagnant water than fresh water in the tank. In other words, instead of a blind practice, the frequency of municipal water supply and family size should together decide the ideal volume of storage required, to avoid both dead investment and unhealthy water.
For most families, a sump for 3,000 and overhead tank for 1,500 litres is more than sufficient for municipal supplies. It also fits into the theory of sump being double the capacity of the overhead tank. Virtually, every family has the habit of daily pumping up as a morning routine; as such, the previous day’s consumption, which may never cross 1,500 litres, gets refilled in the tank. In the event of power cut or being unable to pump up on a given day, the tank storage would suffice for the second day also. The sump and tank together can hold up to 4,500 litres, adequate for a minimum of five days for a family of five. If water gets supplied every two or three days, at least half the stored water gets replaced during the supply time, reducing the risks of water stagnation.
The eco-conscious can further reduce this total storage capacity based on the lifestyle of the family, but should not be increased unless specific reasons demand so.