Rainwater harvesting : Resource guaranteed for the underprivileged | Daily News

Rainwater harvesting : Resource guaranteed for the underprivileged

Water tank at Tharanikkulam Ganesh Vidyalayam, Vavuniya
Water tank at Tharanikkulam Ganesh Vidyalayam, Vavuniya

Today is World Water Day. The Daily News sat down with Executive Director of the Lanka Rain Water Harvesting Forum Dr. Tanuja Ariyananda to discuss what her organization does to combat water scarcity in Sri Lanka. As the world undergoes climate change, seasonal rainfall is becoming more erratic, further challenging scientists and policymakers who wish to ensure water availability for everyone. One such manner of guaranteeing access to water is through rainwater harvesting, whereby rain is captured in large above-ground tanks. Dr. Ariyananda’s organization has set up thousands of these systems to combat drinking water scarcity for people throughout the island.

Excerpts follow:

Q: Can you tell me about the work you do?

A: We promote the idea of collecting rainwater, or rainwater harvesting, for domestic use, especially in areas where water is scarce. Sri Lanka is a high-rainfall country, so you might wonder why we need to do this, but it is very important. Although we generally have good rainfall, from 900 millimeters to 5,500 millimeters (mm) in the hilly areas, we have some pockets that barely get enough rainwater. But the water in these areas is not collected efficiently in my opinion.

These areas suffer from lack of water from time to time because rainfall is seasonable and variable. Some areas don’t get rain throughout the year, but get it in two seasons. In countries like Sri Lanka, rainwater harvesting is ideal, and the basic concept is collecting rain and using it during the dry season.

We have set up about 7,000 tank systems ourselves, and we have worked with other organizations, including the government, the Water Board, and other NGOs, to set up about 40,000 of these systems.

Q: Sri Lanka just emerged from a serious drought. Is this an effective system for supplying water during droughts?

A: Very much so. We get more requests to set up tanks during droughts than during the rainy season, but that is too late, since you should collect rainwater when it is still raining. But I think droughts and floods are now a part of daily life.

The seasons have changed to the drought season and the flood season, rather than the monsoon season, so our systems are ideal for both situations. If you collect water during floods, you reduce the flood level as well, because you are collecting and arresting the water. And then during the drought, you use that water that you’ve saved.

Q: Where are you concentrating your efforts in Sri Lanka?

A: We try to help people all over Sri Lanka, but most of our work happens in the dry zone areas in the North, East, and some parts of the South, like Uva Province.

Q: Can you tell me about the systems you use to collect rainwater?

Dr. Tanuja Ariyananda

A: We mostly set up roof water harvesting systems. We have special gutter systems that deliver the water from the roof to the catchment and into ferrocement tanks. We use chicken mesh as a frame and use cement to build around it. It’s a low-cost system that is generally built above ground. It’s easy to manage and easy to maintain. That’s the basic system, but the type of tank does not matter as long as it can be closed. An 8,000-litre tank will cost about Rs. 65,000 to build, including labour.

Q: Is there some kind of filtration mechanism?

A: Yes, we have what is called a first-flush system where we don’t collect the first rain from the roof because it might contain some debris and dust. We let the first rain itself wash the roof.

Then the clean water goes into the tank. Even before that, just before it enters the tank, there is another filter that takes out any debris that might come in with the water. It’s a homemade filter made from small pebbles and charcoal, with some cloth or mesh on it as well. Any leaves, debris, or unwanted material also get arrested there.

Also, when we extract water from the tank, we don’t take it from the bottom. We allow any sediment that might come in to settle at the bottom of the tank, and then we take water from a little above the bottom so that we don’t get any of the sediment. But people wash out the tanks from time to time and get rid of the debris and sediment.

Q: Are there any problems with this system?

A: The only issue is maintenance. The user maintains the rainwater harvesting system. There is no external person coming in to check on it. You have to maintain it yourself. If you don’t know how to maintain it or neglect to maintain it, you can have problems. For instance, if you leave the lid open, mosquitoes can go in and breed.

The above ground tanks themselves are very solid. They have lasted for 20 years quite well. Also, plastic tanks last up to 20 years, if not more. We have had some problems with underground tanks, and that is why we don’t promote these systems too much now. Roots pierce and crack underground tanks.

Resident maintaining the water tank

Q: How are you funded?

A: We have different funders. That’s always a challenge for us. We always have to look for funding. USAID has been funding us for three years for projects in the North and the Uva Province. We have been funded by the Japan Water Forum, the Korean Water Foundation, and the Canadian Development Agency, among others, in the past. But we don’t give the whole system for free.

We get some commitment from the beneficiaries themselves. They contribute by building gutters on roofs and providing labour during construction. About 15 percent of the cost is borne by the beneficiaries.

Unfortunately, the system isn’t being taken up more because of the initial cost. Rainwater is free, but you need to spend some money at the start. It would be great if a bank or the government could provide that initial investment in the form of a loan, perhaps an interest-free loan.

Q: How do you manage implementation? Who goes and builds the tanks?

A: We have a skilled group of masons scattered throughout the island for that purpose. Every time we work in a district, we recruit masons from the area, and we train them ourselves.

Then they do future projects in their respective districts. We have been promoting ferrocement tanks because they give some business to local guys as well.

We have trained more than 400 masons so far. I should also add that we rarely build single tanks. We generally provide many for a village. We select the number of beneficiaries, do an awareness program, then provide the supplies. We can construct about 15 to 16 tanks in a week’s time.

Q: Are you involved in any awareness campaigns around the island?

A: Yes, awareness is a very important aspect of our work. Although this concept is not new in Sri Lanka, it’s a traditional concept that has been around for centuries. So we have to remind ourselves that this is a possibility. And of course there are a lot of obstacles.

When people first see the tanks, they are not sure whether they are reliable. So, awareness is really important, and we have to do it from top-down and bottom-up. We meet with government agents, and they invite people from that district for an information session on the tanks. We also work at the household level to raise awareness.

When we visit a village, we don’t just dish out rainwater harvesting systems for everybody. We tell them what it is first, and ask them to apply for a system. They apply, and we pick who should get one based on our selection criteria. The criteria are based on a household’s access to water, and anybody who has to go beyond 250 metres to get their drinking water is eligible.

We emphasize helping women-headed households, especially in war-affected areas. We also look to help households that have a lot of children and those that have people with disabilities. Lately, we have targeted people with water-borne diseases, especially those in areas where many suffer from Chronic Kidney Disease.

Q: How have the outcomes been for the beneficiaries?

A: There is initially some reluctance to adapt it in new areas. Everybody wants pipe water supplies, but it isn’t possible for many places in Sri Lanka. If they can’t have water pipes, they want wells, but that’s not always possible.

Even if it was possible, water in the wells is not good for drinking. We have to convince them that this is another option, so we conduct tests with a few people in a village who are willing to have the system, and find out if they want their own systems. We have a huge demand after the tests.

Q: What do most people use harvested rainwater for?

A: They use it for anything you would use water for. But drinking is an especially important one, especially in areas where water is not of high quality. People in areas where there is a lot of Chronic Kidney Disease of Unknown Etiology (CKDu) generally drink rainwater.

But rainwater isn’t used for bathing and large-scale washing so much. They can use it during the rainy season for these purposes, but there’s not enough water during the dry season for bathing.

Q: How clean is rainwater?

A: Rainwater is the purest water. There are only a few places where there is acid rain, but this is limited to areas where there are coal power stations. So far, we don’t have a lot of problems with acid rain here. But in urban areas, where there is a lot of vehicle exhaust, the pH of rain can be a little low, say between 4.5 and 5.

In those areas, I wouldn’t promote rainwater for drinking, but you don’t need to harvest water in those areas because most of them have pipe water supplies. But any other uses, like toilet flushing, gardening, washing cars, you can use rainwater for.

In my opinion, it’s a crime to use pipe water for any of those purposes because, for instance, in gardening, you’re using chlorinated water, which is bad for plants and the country.

Q: Do you think this is the future of self-sufficient water management in Sri Lanka?

A: I hope so. Even if you have another water supply, whether it’s a pipe water or well water supply, having a rainwater harvesting system is not a loss. It’s only a gain, because you can use the water for anything. 

Water tank at Chilawathurai G.M.M.S, Mannar

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