Useful “Used WATER”

Useful “Used WATER”

Demand on existing fresh water sources is increasing with time and availability of water for domestic needs need to be planned from multiple sources.

Used water will be the logical source for generating secondary water for use in domestic households also.

Two types of waste water generated at homes are Grey water and Black water. Grey water is used water from non-toilet plumbing fixtures such as showers, basins and taps. This water is ideal for toilet flushing and gardening if used with appropriate precaution. Black water is water that has been mixed with toilet waste. Black water requires biological or chemical treatment and disinfection before reuse. For single dwellings, treated and disinfected black water can only be used outdoors, and often only for subsurface irrigation.

Advantages of reuse include reduction in water bills, usage of fewer fresh water resources, gardening during drought or water restrictions, cut down in the amount of pollution going into waterways, helps to save money on new infrastructure for water supplies and waste water treatment. The quality of reused water depends on the treatment system, the water’s previous use and the chemicals used at home. Few measures at home can simplify treatment requirements of grey water such as minimizing the use of cleaning chemicals, use of natural cleaning products where ever possible, use of low or no sodium laundry detergents, soaps and shampoos, etc.

Washing Machines usually require 70-140 liters per load of clothes. Hence it’s better to use the machine for full load to save water. A Front Loading washing machine saves 50% of water when compared to a Top Loading washing machine. Also you can recycle the water that your washing machine spews out every day; this needs some infrastructure like a separate sump with a pump and a dedicated overhead tank which can be connected to the toilet flushing system. One of such method is adopted in a house “Sourabha” in Vijayanagar, Bangalore.

 Water used in the washing machine in this house which may contain dirt, sweat and some grease from the clothes, is pumped up to a tank which is kept at a higher elevation for storage. This water is then passed through an aeration system (water flows through an open channel to remove bad odour). The treated water is used for toilet flushing. You can also use the used water from washing machine for toilet flushing by collecting in buckets.

 In this house, kitchen sink outlet water (without soap or chemicals) is used for watering plants. A water trap for the outlet pipe is required to avoid entry of cockroaches and other insects. 

“Reduce the usage of precious fresh water - Reuse and Recycle water”

RO Reject Water can be reused for Mopping the floor

Suncity Apartment in Bangalore on Cloud9 for water needs!

'Suncity Apartment' in Bangalore on Cloud9 for water needs!

High rise buildings have been popping up as consequent outcome of rapid economic development and urbanization. Bangalore is a distinctive city known for its canopy of lush trees that not only serve as homes to the fauna around but make the new high rises, less of an eye sore.  Nonetheless there aren’t any adjoining rivers to provide for the city’s growing population. There are several thousand families that migrate into the city each year; consequently there isn’t a water source to gratify the growing dearth. Land sharks have encroached existing lakes to set up residential buildings with high density living. High rise buildings offer homes to the new populace but fail to provide the families with an adequate supply of year round water. Increased water consumption is a great concern to the city. It is predicted that nearly half of the city’s population will have to be inevitably evacuated by 2023 if not for immediate measures to make the city more eco-sustainable! With no customary sources such as rivers and glaciers to meet the growing needs of the city, new means of water supply has to be established.

 At 11 stories high, the Suncity apartment is just another residential building with shortage of water for its 5000 residents. The Suncity apartment has been constructed on parts of the Belandur and Iblur Lake with no appropriate water supply. Excessive rains cause flooding in the apartment due to poor management of water. Sandeep Singh, a resident, weary of purchasing water from 120 tankers every day, proposed to take up Rainwater Harvesting (RWH) to counter the lack of water supply in the building.

  “We were in great need of an alternative as a BWSSB connection to get Cauvery water would cost us 2 crore rupees. We had resorted to spending about 50,000 rupees every day for the water we import from tankers”, he said.

On researching the internet, he found abundant data on the KSCST website, which gave Sandeep a deeper view into the working of harvesting. Inspired by it, Sandeep approached the RWH helpdesk at KSCST in assistance. “The RWH team conducted an awareness campaign for my fellow residents on the importance of conservation and judicious use of it. The simplicity to harvesting rainwater had impressed us all. There was an overwhelming response to the idea. The RWH team provided us with a plan and every one of us contributed to build 3 large sumps and an over head tank of 35,000 litre capacity. Ever since the number of tankers has been reduced to 80 from 120! ”, he said. Although Rainwater only augments to the water supply, it has made a big difference to these residents.

  “We have implemented RWH to the 15 out of 20 blocks in our apartment. The sumps for each are interconnected and have been filtered using First Flush Lock (FFL), ensuring the quality of the water. The water from tankers along with the harvested water suffices the need of 1200 families. With RWH, 35% of our water problems have been resolved. Although RWH can suffice only a part of our needs, it can be used for domestic purposes without any treatment.

 We have used FFLs and pebble bed filters to keep it clean. AR Shivakumar and the RWH team were instrumental and the residents of Suncity are extremely grateful to the technical yet practical assistance that we have received” he explained. For a heavy rain of 2hrs, 40000 liters of water gets collected in a day. During the rainy season they save about 30-40 water tankers per day.

Water problems are faced by many and RWH is the ideal solution. Intense demand for housing inside the city and the acute shortage of available land leads to building taller structures that provide cheaper homes than independent housing. This leads to increased water consumption in a concentrated area and is a great concern in view of its impact on the ground water table of the region. Green buildings, eco-architecture and partially sustainable buildings are an answer to achieve a favourable and healthy living environment and optimum use of harvested rainwater is a way of alleviating the existing water scarcity problems.

Story by: Bhargavi, Sachin & Abinitha S Kumar

GO AHEAD, HIT THE ROOF!

GO AHEAD, HIT THE ROOF!

Simple interventions on your roof can help you harvest rain. Here’s how

In cities, buildings are usually constructed with rooftops of Reinforced Cement Concrete (RCC), Mangalore tiles, asbestos / galvanized iron / zinc sheets etc. Rooftop rainwater usually flows into storm water drains outside the plot area. As roofs are built with hard material, large quantities of rainwater runoff and loss due to evaporation and percolation are minimal.  So, rooftop rainwater is just waiting to be harvested. You can either store rooftop water on the roof itself, at ground level or below the ground, using storage devices like masonry tanks, ferro cement tanks, or plastic / metal containers.

The process

Collection: Roofs can be broadly categorised into flat roofs and sloping roofs.  Flat roofs with RCC have water proofing on the surface as a surface finish. This surface is provided with a slope towards the down-water pipes.  For efficient collection and effective usage, the roof needs to slope towards the storage device. This will minimize pipe length to the storage system.  

Sloping roofs with RCC, Mangalore tiles, asbestos sheets or steel sheets lead the water to the lower edge of the roof. A gutter made out of sheet metal or PVC has to be installed at the lower edge to collect and channel water to the down-water pipes.

 Channeling: Down-water pipes made of PVC, HDPE or cement, can be used for transporting rainwater collected from roofs to the filtration system before storing. The size of the down-take pipe varies depending on the roof area, which is connected to the down pipe.

Filtration: Rainwater collected on the roof is very pure and clean.  However, there are many substances, which may contaminate this water such as leaves, bird droppings, dust etc.  These contaminants need to be filtered before the rainwater is stored.  There are many filtration systems such as sand bed filter, PopUp filter and stabilization tanks.

Sand bed filter: Sand bed filter is the traditional method of filtration where coarse riverbed sand, pebbles and aggregates are filled as layers, one above the other, in a confined masonry structure. Rainwater is allowed at one level and filtered water is drawn from the other.

PopUp filter: A simple PopUp filter works effectively for residential buildings and smaller institutional or industrial applications. It has three components – rainwater receptor, flush valve and filter.  

Stabilization tanks: Rainwater is allowed to flow through a series of small tanks and, by providing an entry and exit for water at strategic positions, impurities are trapped in the stabilization tanks for subsequent cleaning.

Cost is determined by:

                     * Quantity of rainwater to be collected

                     * Type of surface from where rainwater is collected

                     * Existing structure and fittings for rainwater collection and flow

                     * Type and capacity of harvested water storage device

Rain dance on the rooftop

Rain dance on the rooftop

Bangalore is a unique city because it has neither river nor sea close by. Our erstwhile rulers had planned lakes and water bodies to collect rain water. It was the most systematic, common-sense community approach to address the water needs of the population.

Traditional Open well

The water thus collected was used through ‘kalyanis’ or step wells and open wells. Open wells were recharged by tanks, water bodies and surface water flow.

Kalyani being restored by volunteers

Kalyani in the premises of a temple

But as urbanization happened, this approach could not be sustained. Water sources got polluted and dried up. Encroachment and diversion of natural drainage of rain water soon turned most of these tanks into garbage dumps!

Ulsoor Lake

We began to look at far off places like Hesarghatta and Thippagondanahalli for water supply. As demand continued to mount, we went up to 95 km to River Cauvery to meet our water needs. And now we are in the unique situation of pumping water (most our requirement) from a distance of 95 km against a gradient of 500 



meters!
Urbanization and increase in population are exerting tremendous pressure on conventional water supply. The time has come to look for new sources or at recycling water. Recycling is not a phenomenon that is well-accepted in India due to social reasons. We just cannot imagine recycling our bath water!

                  Ulsoor Lake

Why fret when there’s an easy solution on hand: Rainwater. It is available in abundance in a place like Bangalore which receives 1000 millimeters of rain water (or 40 inches of rainfall) annually. This translates to 2, 30, 000 liter of pure water in a plot of 2400 sq ft — a plot where an individual can comfortably build a house / apartment. When we have such a boon, why don’t we use it? If we do, at least 50 per cent of our water requirement can be met with this intervention. And the pressure on a service provider like the Bangalore Water Supply and Sewerage Board (BWSSB) will dramatically come down. The BWSSB currently supplies water to around 7,00,000 properties only (against over 18,00,000 properties of Bangalore). If everyone practices rain water harvesting in Bangalore, an equal number of new connections can be facilitated and in the next 25 years, Bangalore can still sustain with its available water sources.

So what exactly is rain water harvesting?

It is a very simple intervention to collect rainwater. The first and easiest approach is rooftop rainwater harvesting. Collect the roof water which is already flowing through a down water pipe, attach a filter at the end of the pipe to separate the dirt, dust, bird dropping and leaves and divert the filtered rainwater into a storage unit such as a tank / sump. This can give you sustained water supply during the rainy season.

Cement ring well in a residence of Bangalore created for ground water recharge from roof top rainwater 

The excess water which overflows from the sump or tank can be used to recharge the groundwater through a pre-cast cement ring open well. When the rainwater is discharged into this well, it slowly percolates into the groundwater table and can be withdrawn through a borewell or an open well. These two systems can provide sustained water supply throughout the year. Rainwater can also be collected in playgrounds, parks and roads for large-scale groundwater recharge. Harking back to the time when I was in school, I remember fetching water twice a day from an open well outside my village, Ammanaghatta in Gubbi taluk in Tumkur district. I did this religiously all through my childhood! I saw piped water only when I moved to Bangalore. But soon the bore well in our house in Vijaynagar dried up and I had to fight for water for the first time in my life! At that time, I was working on sustainability projects. So I started planning a house which would use Nature’s gifts for its needs. The outcome is ‘Sourabha’. I will take you on a tour of ‘Sourabha’, in my future posts!