1 The Background
Rain water harvesting has assumed increasing importance since a couple of years. This is because of the ever increasing scarcity of drinking and irrigation water needs. An important reason apart from increasing population, is the abuse of water in Industrial and domestic use.
In this thread I would like to discuss about currently known techniques being used / commercialized. These techniques can be classified as
1. In situ ground charging - GC-IS
2. Ground Charging at Lakes - GC-AL
3. Harvesting drinking water in situ storage tanks
The ground charging at Lakes seems to be the oldest method known to man, where as in situ ground charging is of recent origin. This method however is yet to pick up in our country. The GC-IS was started in Australia 40 years back and has been since implemented in countries like USA, Malaysia and some countries in Europe perhaps. As per BWSSB there are several different variations of RWH techniques. These techniques need to be evaluated on a scientific basis.
2 Analysis of a solution for Drinking water requirement by different RWH methods
Given Below is a spread sheet application which can be handy in the present context. It is helpful in getting any parameter given the other two, in the RWH context. You are requested to try out if you can lay your hands on a suitable spread sheet. Try and get one in metric units.
Table 1 A ready reckoner for calculating Catchment area
|
Annual Rain Fall |
Water Requirement |
Catchment Area |
|
Inches |
CFT per day |
SFT |
|
20 |
5 |
1095 |
|
20 |
5 |
1095 |
|
20 |
5 |
1095 |
This table can be used for getting a quick estimate for your RWH application. It is possible to utilize the whole of the site dimension for any residential building or an apartment block.
There are some Architects who are building houses and apartment complexes with RWH. There could be several techniques of RWH including the Australian one GC-IS known as Chari’s Technique in Bangalore. All these and any other known could be evaluated for their comparative merits and demerits, including cost effectiveness.
The success of the application to any situation depends upon the cost effectiveness analysis.
Forward this Blog entry
Comments
RWH is now Manadatory
PSA,
As you are aware, installation of RWH systems in buildings (old and new) is mandatory after Karnataka Government passed the relevant bill last week.
Your calculation method in metric figures works something like this:
Rainfall Consumption / Day Total Catchment Area
in mm in Ltrs/Day in SQM
970 135 50.80
Information on any two of the above parameters will give you the third parameter.
Am not sure what you mean by GCM, but it certainly is not Chari's Technique!
It is a very simple technology where underground retention tanks are made in geometrically designed matrix tanks of a specific size to configure into modular tanks of any size. The geotextile wrapped around helps it ensure that only treated water gets infiltrated. The same tanks with geotextile wrapped around it can double up as retention tanks to store water if we wrap an impermeable liner before installing them underground. Modular nature of tanks allows it to be installed under roads, any building or car park areas etc. Capacity of rain that it can hold is unlimited - limited only by the size of the catchment area.
I personally think this tried and tested technology scores over other indigenous technology because:
1. It offers 100% harvesting of rains against normal 80 to 90%
2. It offers drinking quality water of 98.7% purity which no other RWH system offers; this is an open challenge by the Australian inventors of the system.
3. Being modular and being installed underground, it remains free from photosynthesis and algae formation which is a common feature in most concrete sumps. it also remains fresh because of a capilliary action that takes place automatically aerating the stored water.
4. Cost-wise the comparison should be made in terms of retention tank cost. Any Civil contractor will confirm that a concrete tank normally costs between Rs. 6.50 to Rs.7.50 per Cubic Metre. Our Tanks cost just Rs. 5.50 per cubic metre.
We believe we supply Water free of cost as it is God given. We only charge for our retention / infiltration tanks!!
Regards
RKC
Corrigendum
Point 4 above should have read Cubic feet instead of cubic metre. Sorry for the mistake
RKC
Apologies
Dear Friends,
I must hasten to apologise for making this forum into a 'promotion of my company's technology' platform. I wish to assure all praja members that that certainly was not my intention. I just got carried away in trying to explain our technology in comparison to traditional technology. But on reflection I realise this is really not the forum to do so.
As PSA says everyone is aware of this new RWH technology. Apparently people's acceptance depends on cost viability. And to support lower costs I understand people are willing to compromise on quality and efficiency.
So be it. Let the traditional methods be employed and I sincerely wish it all success.
Regards
RKC
RKC
Charis Technique - All the best.
/There could be several techniques of RWH including the Australian one GC-IS known as Charis Technique in Bangalore/
PSA Sir, your post has rightly pointed out that RWH in many forms are being followed depending upon the tropical conditions.
RKC, you did your best to float a product with Charis Technique and may be someday it will click but it may be a wee bit difficult to use Praja for such marketing technique/strategy. When your product becomes affordable, replicable, sustainable, I will be the first one to request for installation of one at my place.
During my interaction with NSS groups of various colleges, I have been successful in creating awareness for adopting micro RWH in many villages around Bengaluru and Mysoru.
- I used a few mugs of water for creating miniature models and by making small trenches in a slopy area, with inter connecting canals to feed the the other trenches dug in different lower levels in different directions so that when the upper level mini tanks get filled and overflow. This way I was able to convince some of the panchayat members and farmers that the lands in the upper portion need not remain barn due to non availability of some water for growing some kind of crop/vegetable etc., - otherwise, pumping/carrying water from the little tank at the bottom level could be a very taxing proposition.
- Digging trenchs as RWH is old hat but when it gets filled, the rest of the water overflows in a hapazard manner - still it may percolate and replenish the ground water but - if trenches at different levels are provided, connected with a systematic canal innovative idea may help store more water andavailable for that level of the land that may grow some crop or the other by using the water available at that level itself.
- Zenrainman and Mr.Charis Technique - any comments for improving my two paise idea?
Infiltration through trenches
Dear Mysoremath,
I suppose by trenches you mean storm water drains on either side of any road. If that be the case, then currently, in Bangalore at least most trenches are lined on three sides with rough granite lining, in the belief that storm water will move swiftly from point "A" to point "B".
Two processes do not actually happen in this methodology. The storm water does not get infiltrated as it is made to pass through impervious base and secondly open drains are invariably subject to people throwing any number of things into it ultimately leading the trench to clog which then makes rain water to overflow on to the road.
What is therefore workable in your solution is if the trenches are not lined with impermeable liner like concrete or rough granite slabs. But that too has its problems. Besides slush formation and muddy water flowing, the rate at which rain water falls and the rate at which it will get infiltrated is invariably seen to be a mismatch. So flooding and overflowing on to roads during heavy rains is inevitable. If unlined trenches are still meant to be channels taking the rainwater from point "A" to point "B", it still will carry only muddy water.
I am not too clear about trenches at different levels. How do you achieve that?
I hope my two paise worth is useful.
regards,
Chari
RKC
Pl. am I refering to Bengaluru?
RKC Sir
I am referring to non-adoption of optimally feasible RWH in rural areas. RWH was an unexplored area at grassroots level except in some villages where 'hoolethuva kaaryakrama' was being taken up in a few isolated educated gram panchayat areas. Now it has gained momentum and....
Recently, the NREG programme is effectively being used for creating more storage capacities of rain water by de-silting tank beds hitherto ignored for want of knowledge and financial support.
My two paise idea is in that direction and not in namma Bengaluru where almost every SWD is chocked. Pl have a look at what I have mentioned in my post w.r.t rural populace and react. We must also remember that SWDs are almost unheard of in villages and RWH through such improved SWDs will continue to be a dream.
- Vasanth Mysoremath
Regret Unable to Decipher
Dear Sir,
Regret even after reading and re-reading your original post, I am unable to get the gist of what you are recommending.
What really is the connection between Storm Water Drains and Rainwater Harvesting in the rural context? What we normally understand by SWD is that they are laid on either side of even a muddy track to drain away excess rainfall. I really do not understand how this drain water can be used as rainwater harvesting. What about storage tanks? Does not RWH require storage tanks?
The percolation tanks in villages act as storage tanks. However it is subject to pollution due to its open nature, sunlight / photosynthesis effect and eventual algae formation. It is scientifically proved that water only remains fresh and clean in dark containers which is not subject to sunlight exposure. In fact in cities, our using Syntex Tanks of black colour, but exposed to severe sunlight on being placed as overhead tanks on roof tops is actually harmful to the quality of water that is being stored.
My twp penny bit please!
RKC
Imagine you are in a village....
For a few minutes, forget hi-end techniques etc. Imagine you are in a village.
Recap: Most of the human habitats are found around water resources either along perennial rivers or in valleys (Harappa, Mohenjodaro / Indus valley civilisation etc.) and where fertile soil/lands are helping them to grow their staple food crops.
- You are in a village, in a valley ,with a few acres of land at different locales; a tank exists to which water flows from the upper slopy reaches/ catchment area. Your only source for irrigating your lands at different levels of the upper reaches, is rain water but water runs down and reaches the tank. Your land may soak in that much of water depending upon the sandy or loomy nature of soil. If it rains for longer monsoon/south west monsoons durations, you can grow two crops - otherwise, you cannot get even one crop. Transporting water from the village tank to the upper reaches is a costly affair and not an easy proposition.
- Our experience is that a few hours of heavy showers can bring in copious rains that needs to be harnessed - RWH.
- Solution: excavate 20 feet X 30 feet of your land with a depth of 5-10 feet - create mini canals that lead to this mini tank, gets filled, starts over flowing - lead that overflowing water with left and right bank canals for reach such similar mini tanks excavated in the lower reaches and with a series of garland mini canals, the entire upper reach lands can have some water readily available in those mini tanks for irrigation purpose at that level/height of your irrigable land. Water flows finally into the tank, at the foot of the valley and will be available for use by the womenfolk for their needs.
- Hope its OK and it is explained like KG school.
- My two paise, if one can call it an innovative idea.
- /vasanth Mysoremath
Well Presented
My ancestral land in coorg has the VKM idea implemented since 100 years and more. Even to day my cousins and their children are living there. They cultivate Coffee, Cardamom, Paddy, Pepper etc. They live in houses among the coffee estates on hill slopes. There are modern day resorts near Madikeri. A 7 star hotel too is planned. Whole of coorg is on a beautiful hill range known as the Western Ghats. I have been in villages and towns of coorg hence I can understand what VKM sir has so nicely explained.
Coorg, coonoor, Simla and many more places in India have systems exactly similar to what VKM has explained.
RWh in Villages
Understood, but distribution of available rainfall between upper reaches of a village and lower valley areas for irrigation purposes is an age old practice and newer technologies have no cost effective "better" solution than accessing water through check dams and man made canals.
Although in Developed countries our technology of storing water where it falls in underground tanks is also practiced by rural folks, in India it is not likely to be cost effective.
Unless Government steps in and finances such "high tech" RWH systems for villages through Gram Panchayats, villagers are better off accessing polluted water for irrigation and secondary use purposes at least. As long as no distinction is made between water used for secondary purposes and water for drinking and cooking, the open check dam system is better than nothing at all.
Some people actually believe consuming water which is not necessarily pure to the extent we are able to provide will increase people's immunity level towards diseases. As long as we hold such views, no amount of promoting any technology - costly or cheap - can be considered worthwhile.
RKC
RKC
Pure Vs Not so pure
@Chari
“Some people actually believe consuming water which is not necessarily pure to the extent we are able to provide will increase people's immunity level towards diseases. As long as we hold such views, no amount of promoting any technology - costly or cheap - can be considered worthwhile.”
While Importance of Technology cannot be overstressed, looking for near best technology is not an anathema.
Example: Is it good to drink distilled water which is 100% pure, apart from affordability issue?
PSA
Distilled water is not
Distilled water is not drinking quality water. It lacks essential minerals which are beneficial to human health. Distilled water cannot be obtained by filtering rainwater. There is a specific scientific process to obtain distilled water.
So distilled water and drinking water without contaminants are like chalk and cheese.
I dont know why using ecologically friendly technology and offering high quality drinking water should be considered to be expensive and hence the nearest best, but markedly cheaper system should be favoured?
Actually Rainwater is free of cost for everybody. It is the scientifically safe and clean way we store it / filter it and supply it with no headaches is what costs money.
Look at RWH in this perspective and all resistence to using technology will vanish!
RKC
If no rains? Better have alternates- Solarised desalination
@ RKC
/Distilled water is not drinking quality water/
OK; then what about desalinated water from sea water? Is that also chalk and cheese or should we add some mineralised water and drink?
World will have to come up fast with affordable/economical/replicable methods to tap solar heated sea water conversion for use by people.
- Global Warming, Global Dimming, contaminating acid rains that are polluting ground water, Climate change, El Nino and other factors are clear indications of what is in store for our future generations and it is time that the present responsible generation makes a proper online course correction to the various elements that are creating environmental degradation problems, for posterity.
- Live moderately and modestly.
-Vasanth Mysoremath
Desalinated water can be
Desalinated water can be drunk if the desalination has been properly done. The best known method is that of Reverse Osmosis, but this technology wastes as much as 70% of water under treatment / desalination!
As it happens a revolutionary Electronic Water Purifier (EWP) - the table top variety - has been invented by an American Company which desalinates water which has up to 5000 ppm as salinity. Beyond that it cannot handle. Costs US$ 250/- per unit which dispenses 100 litres per day.
My question to you is, should one bend backwards to do course correction without taking the help of technology? In the name of modest living and being content with what we have, should we deprive future generations of the benefit of technology? Rest of the world does not think so. Is it a case of us feeling a sense of sour grapes which somehow never gets articulated?
RKC
desalination device
Dear Mr. Chari, Do you have more details on this device? Is it electrically operated? What are the running costs? What is the principle of operation? How about maintenance costs?
Thermal desalination typically works well for water containing non-volatile contaminants. However, if there are any volatiles (typically some organic contaminants), you will end up with the contamination in the product water.
The device is called EWP
The device is called EWP (Electronic Water Purifier) and is made by a Texas based company called Sabrex Inc.
It operates on electrode principle and has an autmatic purging system whereby the sodium collected gets purged when it reaches a particular level.
The device is also useful for removing fluoride, arsenic, iron and nitrates in water.
If you let me have your email ID I can send you their flyer.
Best wishes
Chari
RKC
I saw the product online
I saw the flyer for EWP of Sabrex that came up through a google search. I did not fully understand the physics of the technology, however, from their description one can conclude the following.
Their technology will probably clean slightly hard water, but it will not desalinate a source like sea water. The limits of the device are quoted as 2500 ppm tds. That is about 0.25% dissolved solids. Seawater is a whopping 3.5% salt. Also any organic contaminant will still stay in the water using this technology.
I love technology if it can help the poorests of the poor
@RKC
I find variations in consumable waterwith tech based Sabrex - water convertor. Your/Sanjay's posts.
- As you know ours is a poverty ridden people's country and we can find many foreign visitors doing 'slum tourism'. Affordability is the major question that haunts our brothers and sisters in BPL.
- honestly, I can't go in for a Sabrex with such differences and as you know Indians are very traditional in their spending habits.
- this is the reason why i keep hankering about innovating affordable, replicable, sustainable and measurable tech based solutions for converting our bountiful salinated water that has 3.5% salt content.
- I am also dreaming of tablets prepared from ayurvedic/homeopathy/ herbal / aromatic roots or plants to be put into a glass of water so that the tablets suck the saline portion and leave pure water.
- This outlandish thought is derived from the simple fact that the sea water got collected from the raindrops that are pure potable and is considered as elixir of life. It turns saline after it joins the sea water. That means, if we can remove the agent/reagent/element/ chemical transformation that converts sweet rain water into salinated water, can we not get back clean water by segregating or detaching that substance?
- Another thought - similarly, what is the raw material base of plastic? It is crude oil. After refining etc., different levels of end products are obtained and used in different areas where oil is required. One such product is plastic carry bags, etc. What can be done is break this end product plastic and convert it into its original form - crude oil - Not possible? Yes I can visuaulise it as a possiblity through scientific and technological innovative solutions. Right now, in some corner of this world, it is being tried with positive results.
- I may be able to find something.
- Vasanth Mysoremath
perpetual motion machine
Dear VKM sir,
What you are suggesting - suck the salt out of water or covert plastic back into crude oil is what a thermodynamicist like me would call a perpetual motion machine. To state it simply, certain actions are irreversible. In order to reverse them, one would need to invest a lot of energy/power. It cannot be done for free. In other words, mixing salt with water is an irreversible process. It does not reverse itself of its own accord. So the idea that you can add something and separate all the salt from the water without investing significant energy, heat, power, electricity etc. - according to the science we know today, that cannot happen.
Same is the story with plastic... the amount of energy for a process that will convert plastic into a micture of relatively short chain hydrocarbons will be far more than what you could recover from that crude. That is simply the rule of nature. We are yet to find a situation where this rule is violated.
A gem of a thought
VKM’s recycling plastic is a gem of a thought, IMHO. Though sanjayv has valid apprehensions, it is not an exactly the perpetual machine concept. It is on the other hand a sustainable concept in the long run. Let me illustrate by giving an example of what is sustainable in nature. Wish VKM sir keeps working on this innovative idea of his towards a fruitful end.
Sustainable naturally:
The plants grow food. We eat the food and produce waste which is manure to the plants. The plants again grow food consuming the manure. The net result is we are getting the energy involved from the sun continuously. Thus there is this sustainable cycle in nature till the sun shines.
sustainable
Yes PSA sir, but you have energy input from the sun and vast quantities at that. It is only the materials (minerals, nutirents) that are getting recycled. So the second law of thermodynamics is still intact. maybe I should not say perpetual motion machine, but definitely the second law of thermo is the basic, underlying constraint.
Oil, coal etc are themselves formed by decomposition of hydrocarbons, as the oxygen gets squeezed out in the oxygenless atmosphere deep belpow the earth, where there is high pressure and temperature (all energy input) over millions of years.
Thermodynamicist Sir, is there anything impossible? U asked 4 it
OK here we go....
Plastic to crude
I do these things for a living so I know a thing or two.
Theoritically, what VKM is suggesting is possible. But again, in the current state of technology and economics, it is simply not a commercially viable option to do it.
Details
One can use a cleverly designed gasifier to convert plastic into some basic gases like Carbon monoxide, Hydrogen etc and use something like Fischer-Tropsch process to get some hydrocarbons that can be used as fuel.
Bottlenecks
However, there are several problems in realising this in an economically viable way.
Due to these limitations, it is not commercially viable to do convert plastic into useful energy.
In fact, although there is plenty of bio-gasification technology available in India, it is not a commercial success due to very similar reasons.
Of course if the cost of traditional energy goes up or if a technological breakthrough brings the costs down, these alternative methods can indeed be a viable option.
(Sorry for turning RWH thread into an energy one. We can start a new thread if there is interest)
-Shastri
Plastic reuse
Off topic again .... sorry
Shastri,
Is it possible to make new plastic covers out of old plastic sheets. ie can it be a raw material for new plastic that is made. What is stopping that ?
Suhas
Old news paper and plastic
Like old news paper old plastic can be sold at old paper mart. The rag pickers now days are seen with very large nylon bags to collect empty plastic bottles and old plastic bags. The plastic disposal is not a problem any more.
There is nothing in a house hold that cannot be recycled.
Pl.get back 2 water issues/hive innovatives on plastic 2 a post-
Dear Prajas,
Make your kids try an experiment - this could be an educative scientific task for them and for us to learn from their observations - This free solar heat generation experiment won a prize in a science talent competition conducted at the Nehru Planetarium last year with which I was associated:
Requirement: large plastic bowl, a few large rubber bands, crystal salt about 200 gms, one litre of water (if you can get sea water, still better), a thin transparent plastic sheet, one small steel cup, one big steel ball and a small steel ball, place with good sunshine.
Method: identify a place where there is optimum solar explosure -place a stool and on that place the plastic bowl - dissolve the crystal salt in water in the bowl, taste the content of dissolved solution by putting one or two drops on your tongue - put the large steel ball inside the steel cup and gently keep the cup in the center of the bowl so that the cup will not float or wobble - see that it remains stationary - spread the plastic sheet - fasten it with the help of rubber bands so that air circulation is arrested - now, gently place the small steel ball right in the centre of the plastic sheet so that the weight creates a slope to the centre of gravity and just above the cup inside the bowl.
- Watch changes - after some time, the solar heat warms the sodium solution in the bowl, starts evaporating, plastic cover becomes foggy, outside cool weather cools the top of the plastic sheet, converts the evaporating fog into water and due to the slope, it travels to the center and the graviational pull makes the collected water drop into the cup,
- After some time, when enough water is collected, open, drink the water and note how it tastes
(Mr.RKC's Distilled water?)
- This is the micro model - in the industry sea water converter scale model, the cup will be a large fastened vessel with a hole in the centre - instead of the plastic sheet, the scale model will have thin industry scale curved glass pane and the rest is left to your imagine. There will be a mechanism to remove the sodium periodically and to market it as a bye product.
- OK Prajas, I am ready. There may be variants elsewhere. But the solar based idea may work out cheap for Asian tropical climate where at least 200 days of warm solar energy can be derived.
- make your kids do it and let them come up with improvisations.
- one request - think positive - every question that comes into your mind on this will also have a hidden answer within it. Try to find it.
- Watch out for further innovative posts in a separate window.
- Vasanth Mysoremath
Thermodynamicist sir question...
Dear VKM sir,
I certainly do not appreciate what is coming across as sarcasm. However, here is my response. From a chemical engineering perspective, there is no reason not to be able to covert plastic waste into liquid or gaseous hydrocarbons. I can with my very limited experiece design a process to squeeze out some hydrocarbons from plastic raw material. Surely, a chemistry professor will do a much better job.
All I was trying to say was that in the larger scheme of things (from a whole system perspective), looking at the input required in terms of materials and energy and the output that comes out, it generally turns out to be a very low yield process or something that is not viable. This is my experience from several years spent in the energy field before my current job.
Ddear Mr.Sanjay,
we were discussing water issues but plastic surfaced and with due regards to your scientific knowledge, let me hive off this with a request to you to browse and get in touch with our friends who seem to have successfully adopted this recovery of natural elements that have undergone various processes:
http://www.goodnewsindia.com/index.php/Magazine/story/alkaZ/
You will find complete details and it may be of interest to you also, academically and I am also on an innovative platform at http://ngopost.org which will be of great interest to you because many of us are giving to the world such innovative tips minus commerce for the sake of bettering the world of tomorrow and future generations.
You have used the word sarcasm... pl do not. At the age of 65, i do not need to be that kind.
Cheers
Vasanth Mysoremath
thank you
I am failing to make my point. Never mind...
Thank you for sharing the information on Prof. Alka's process.