Catching rain

Mizos turn to rainwater harvesting as alternative option

 
By R K Srinivasan
Last Updated: Sunday 07 June 2015

Catching rain

-- (Credit: Nitin Sethi / CSE) The city enjoys an average annual rainfall of 2,500 millimetres . Traditionally, this has been the only source of water and was very popular among residents. Traditional Mizo houses have a sloping roof designed for rainwater harvesting. Water from the rooftops flows through gutters made of bamboo or metal sheets and collects in rainwater tanks made of galvanised tin sheets.

An underground reservoir of 5,400-kilolitre (kl) capacity was constructed on an Aizawl hilltop by British civil servants, a hundred years ago. A major part of the town relied on this reservoir for its water. But the scenario has changed.

Search for water Two water reservoirs of 8,000-kl total capacity were constructed in 1953-1954 at Laiputtlang, a high area in the city, to harvest rainwater, but soon the demand outgrew supply. A fresh search for water began in 1961. Two rivers, the Chite Lui and Ser Lui were surveyed but they were also found inadequate. Tlawng, a river located 18 km west and more than a 1,000 m below the city was later identified as a probable source. In 1964, the quest for rainwater harvesting was abandoned and the first piped water scheme to supply 67.5 litre per capita per day (lpcd) to the city commenced. The project, based on the 1963 population figure of 20,000, was completed in 1972.

Phase i of the Greater Aizawl Water Supply Project (gawsp) started in 1983 and aimed at supplying 10.8 million litre per day (mld) to a population of 80,000. Under this scheme, completed in 1988, water was pumped from the Tlawng to a height of 1,045 m. This is the second highest water supply project after the one in Shimla. It resulted in exorbitantly high operation and maintenance costs and became a major concern for the sustainability of the project. By the time the project was completed, the population outgrew the estimated capacity. The leakage loss also went up by 35 per cent and the search for water recommenced.

The Phase i water supply scheme was designed to cover only central and southern Aizawl, but on public demand, water was distributed to the entire city. This meant a very low water supply of 35 lpcd, which was grossly inadequate. The scheme covered 38 village council areas, leaving 35 villages without piped water (see map: Phase out). Of the 38 village council areas, families with private water connections receive water for roughly 45 minutes per week.

A small dam was later constructed on the Tlawng river. Water was pumped into an overhead reservoir and flowed on account of gravity into individual homes. This, however, led to high frictional losses and caused low pressures. phed estimates the present level of unaccounted water at about 35 per cent , but in reality it is much more, says Dunglena, a retired phed engineer.

To supplement the current water shortage, the government launched Phase ii of the gawsp with the aim of supplying an additional 24 mld of water to cover an area of 128.9 sq km. The combined production of 34.90 mld from both phases is planned for a population base of 380,000 in 2026 and will pump 78 lpcd of water with provisions for 15 per cent losses.

Less water, more money After spending more than Rs 21.27 crore annually on operation and maintenance, phed is still unable to meet the increasing demand. Currently, about 10.8 mld of water is supplied through this arrangement, whereas the demand calculated at 100 lpcd is 24 mld. phed had made water distribution arrangements through 20,000 home connections and 480 community hand pumps during 2004. The present supply amounts to a per capita supply of 44 lpcd partly covering the city. If all the people in Greater Aizawl were to be served by phed, the per capita supply would fall to 28 lpcd.

A study conducted in 2005 by the Centre for Peace and Development (cpd), an Aizawl-based ngo, found that the per capita water supply of 35-40 lpcd was very low when compared to the national standard of 135 lpcd. cpd's report also found a huge gap of 22.95 mld in the current supply.

Meagre income phed recovers only Rs 2.55 crore through water bills. This is 12 per cent of the total expenditure. The state government grants an annual subsidy of Rs 18 crore, while funds from the Asian Development Bank (adb) are expected for the project's completion.

Additional water

On account of financial constraints, Phase ii was bifurcated. Part i of Phase ii of gawsp is now nearing completion and aims at bringing an additional 12 mld of water at a cost Rs 113.47 crore. In 1997, the project cost was estimated at Rs 71.80 crore and had plans to supply 78 lpcd of water to 300,000 people. The project cost almost doubled on account of delays in implementation at various stages.
"We received a grant of Rs 13 crore from the central government and work will be completed during the 2006 financial year," says Tawnluia, minister in charge of phed. The revised estimate approved by the Central Public Health and Environmental Engineering Organisation (cpheeo) is Rs 113 crore, of which, 25 per cent funding will come from the state and the remaining from the Centre. Part ii of Phase ii, will be funded by the adb. "The existing pipelines cannot take on the additional water that is to be pumped and installation of new lines will hike up the cost further," says Dunglena. He also points out many loopholes in the scheme. "There are a number of shortcomings in the Phase ii scheme. Firstly, it is the insufficient capacity of the installed pumps to pump an additional 12 mld of water Secondly, improvements in the distribution system are necessary to bring about a better quality water supply for residents," he adds.

Multiple sources
The water scarcity, given the inadequacy of piped water and decay of traditional systems, has paved the way for private water-tanker owners to collect water from springs and sell it through 15 water points in the city.

Lallianmawia, owner of Galiliwater point on Tlawng road, says that he collects and stores water in tanks and charges Rs 250 for a 10 kl tanker. The buyer in turn, sells the water for amounts between Rs 1,200 to Rs 1,800. The rate varies, depending upon the demand and distance. Lallianmawia says the spring water was tested by phed and found suitable and says business is good during summers.

Pollution problem
What makes matters worse is that spring water is also under threat for lack of an effective sewerage system in the city. Lalduhwma, member secretary of the Mizoram Pollution Control Board (mpcb), says seepage from the soak pits and discharge of sewage from households are polluting this delicate source. mpcb findings confirm this, though it only monitors chemical content and is unable to look into the biological characteristics like Biological Oxygen Demand (bod) and faecal coliform due to lack of infrastructure.

On monitoring the two springs, Mission Vengthlang Tuikhur in the south and Ramhlun North Tuikhur in the north, it was found that dissolved oxygen levels were as low as 2.4 milligrammes (mg)/l and 4.6 mg/l in October 2005. The normal range in treated drinking water should be 6 mg/l.

Water tariff
Remmawai, executive engineer phed, believes that only the central and eastern part of the city get enough piped water. Out of the 20,000 connections, about 1,270 connections are metered and 18,335 connections are not. A flat charge of Rs 100 monthly is levied on households without a meter. Even this is high, when compared to the water tariffs of other Indian metros. Delhi, Chennai and Hyderabad, pay Rs 40, Rs 30 and Rs 60.

Water service charge is volumetric with progressive tariff rates. Although many consumers in Aizawl are not metered, they end up paying Rs 9 per kl, which is the highest when compared with other Indian cities like Delhi and Mumbai where consumers pay Rs 2 per kl and Rs 2.25 per kl respectively. Water procurement in Aizawl costs around Rs 66 per kl as compared to Rs 8 to Rs 9 in Delhi and Rs 5 to Rs 6 per kl (see table: High rates ).

"People pay only Rs 100 per month, which is very low and the phase ii project cannot succeed with this low tariff structure. With this huge subsidy and poor tariff structure, these piped water projects are not sustainable," says Dunglena. People will have to return to traditional rainwater harvesting for their needs, otherwise the current water crisis will escalate further in the future, Dunglena adds.

Too many people
A study on Aizawl water supply conducted by lea International Ltd, a consultancy firm, found overstaffing at phed a serious problem. There are 995 staff members working for phed. This roughly translates to 50 staff per 1,000 connections, whereas the national ratio is much lower, with Kolkata employing 17.1, Delhi, 21.4 and Chennai, 25.9 persons. The current Asian average is 11.8 persons according to abd's statistics.

The phed staff salary bill is Rs 7.4 crore per annum, which is three times its revenue collection. If the Asian average was applied to phed, it would require only 236 staff members instead of the 995 presently on the pay rolls.



High rates
Proposed water tarif

Item Charges in Rs
Minimum charges Rs 100 per month
Up to 13 kl Rs 10 per kl
13 to 39 kl Rs 20 per kl
More than 39 kl Rs 30 per kl
Source: PHED, Aizawl


Aizawl also lacks a comprehensive sewerage system. Currently water from bathrooms and kitchens is discharged into nearby nullah s and the black water from toilets is handled by septic tanks with a soak pit system. But the city is so highly populated that some houses can hardly find place for soak pits, and they end up connecting septic tanks to nearby drains.

Wrong focus
The current focus is on bringing water and not on sewage that is generated out of it. The city's sewage is discharged into nearby streams and pollutes Tlawng, the only source of water. About 60 per cent of the sewage generated in the city is collected in the Ser Lui and emptied into Tlawng. "The polluted water is treated and later pumped back into the city," says Lalduhwma.

"This is a serious issue. Although phed has made a proposal for sewage treatment plants (stp) and sent it to cpheeo, it has cleared the water augmentation process only and the sewage issue remains unattended with more sewage likely to pile up," he says. Lalduhwma also sheds new light on landslides, "During my site visits, I discovered that wastewater seeps into soil layers thereby setting landslides in motion. There is a higher probability of landslides, where there is excessive wastewater."

Like liquid waste, the city also has no plan for the solid waste it generates. Most of the solid waste from the city is collected and taken 12 km away on the Aizawl-Lunglei road. It is either dumped in the valley or burned causing environmental degradation.

Unending thirst
After the completion of Part i of Phase ii, gawsp will provide 12 mld of water, taking the current supply of 10.8 mld to 22.8 mld. However, the demand in 2011 will be 28.3 mld showing a deficit of 5.4 mld. Even after completion of the entire project, a gap in demand and supply would soon emerge.

Currently, phed is incurring an annual, operational cost of Rs 21.27 crore. This cost is likely to go up to Rs 33.83 crore annually.

The major cause of worry, for all, is the ability of residents to pay for the costly piped water. This tariff will have to increase from Rs 9 to Rs 53.1 per kl if phed wishes to recover overhead costs. (see table: Sustainable rates ). Otherwise, the project's sustainability will be questioned at all levels.

Back to roots
Aizawl residents are worried about the unsustainable piped water supply schemes and are planning to return to traditional rainwater harvesting for their needs. Says Dunglena, "Only 30 per cent of the city is equipped with rooftop rainwater harvesting systems. If done properly, there is no need to run the pumps for at least six months in a year, and this will lead to huge savings."

The immense potential of rainwater harvesting can be simply illustrated . A person normally requires 10 litres per day for cooking and drinking. The longest period of dry days or rainless days in Aizawl are 120. A household of eight members with a per capita requirement of 10 litres can survive the entire year by building a storage tank of 9,600 to 10,000-litre capacity. A house with a roof measuring 6 m x 4 m can harvest 60,000 litres of water annually.

Not only rooftop rainwater but also the surface run-off can be harvested. By constructing contour trenches, the sub-surface seepage can increase and enhance the yield. This will provide more water for people downstream. Also this can stabilise the soil layers and prevent landslides.

The study conducted by lea International Ltd discovered that an additional 67 mld of water could be harvested by constructing embankments on the rivers Chite Lui and Tuirial Lui. These sources located at 500 m, would reduce the lift by half. This would result in an annual saving of about Rs 15.8 crore per year in power bills. adb is only interested in the installation of pumps and pipelines and is turning a blind eye to other recommendations.

The state government is busy in building a mini sports stadium on the Chite Lui riverbed instead of building embankments to harvest rainwater and water from springs. People get fresh water by digging shallow pits half a metre deep, even today.

Sustainable groundwater exploitation coupled with proper recharging measures can be another viable decentralised option. Although the Central Groundwater Board says the city has limited groundwater potential, phed's hydro geologist feels that groundwater is of good quality and therefore borewells with submersible pumps can be a cheaper option when compared with costly pipe water.

On carefully studying the state government's plan it becomes clear that the piped water supply schemes of gawsp cannot fully meet the needs of the residents because of poor centralised planning. Besides, the Aizawl residents can least afford the price of piped water. Serious thought must be given to decentralised traditional rainwater harvesting systems as an alternate source to piped water in Aizawl.

The existing water sources like springs and streams also need to be protected from pollution. Considering the topographic setup of Aizawl, it may be difficult to implement conventional centralised stp s. Hence, decentralised community wastewater treatment plants should be encouraged in the city to treat wastewater, rather than allow it to run off and pollute water sources.

Sustainable rates
Proposed tariff for sustainable water supply

Subject/ year Unit 2004 2012 2016
Population Nos 248,141 286,642 312,153
No. of connections Nos 19,518 51,302 58,816
Water provided to consumers Rs 20 per kl In mld 7.02 7.02 31.54
Per cent of population served % 62 82 85
Average water tariff Rs per kl 9.6 53.1 85.6
Revenue Rs in crore 2.55 499.5 1,024.9
Expense Rs in crore 21.26 47.08 80.75
Subsidy required Rs in crore 172.4 0 0
Source: Draft final report on infrastructure improvement programme: Water
supply, prepared by lea International Ltd, November 2005

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