Science Interviews

Interview

Sun, 28th Feb 2010

A Leak-Stopping System that really Holds Water

Andrew Burrows, I2O Water

Listen Now    Download as mp3 from the show The Science of Water Security

Helen -   This week, we’re looking at some of the scientific issues surrounding water, including how building a dam can change the local weather and how climate change looks set to affect water availability.  First though, the World Bank estimates that every year, 32 billion cubic metres of clean water is lost through leaky pipes.  Considering there are millions of people around the world without access to clean water at all, this seems incredibly wasteful.  But there might be a solution.  A Southampton-based company have come up with a leak-stopping system that really does “hold water”.  We sent Meera Senthilingam to find out how it works.

Meera -   This week, I’ve come along to the head office of I2O water in Southampton, a company whose main aim is to reduce water loss in urban environments, both here in the UK and globally.  They've set about solving this problem by developing a new technology that monitors the pressure in the flow of our water supply.  Here to tell me more a bit about this is the technical director here at I2O, Andrew Burrows.

Typical PVC watermain installation in Ontario, Canada.Andrew -   Globally, water loss can vary between 15% and a massive 60% of the distribution of water inputs.  In the UK, it’s currently running at about 23% of the inputs lost as leakage.

Meera -   Why is water lost in this way and how difficult is it to control that?

Andrew -   Well, even with the latest technologies in water pipe works and network installations, the installation is always going to be a very complex network of pipes with many hundreds or thousands of connections between the individual pipes of the distribution network and also the connections for each individual property.  So it’s inevitable that there will be a level of leakage in the network.

Meera -   You've actually set about solving this problem by keeping an eye on, and controlling the water pressure through our pipes.

Andrew -   Yes, that’s right.  A significant influence over leakage and also over the frequency of bursts in the network is the pressure of water in the network.  Water pressure can affect burst frequency.  So the likelihood of a burst occurring, or a new leak occurring, is related to the pressure, as you would expect.  The rate of flow through an existing leak is also proportional to pressure.  The higher the pressure, the higher the leakage through existing leaks.

i2O installationMeera -   So to set the scene a bit, how is our water distributed from the main source of water to a residential area?

Andrew -   Water is typically sourced from either reservoirs, holes, abstraction from rivers, or desalination plants.  That water is then filtered and treated with chlorine.  It’s pumped into a trunk mains system which is running at a very high pressure.  That trunk mains system comprises of very large diameter pipes that feed into the distribution network through metres and fixed outlet PRVs which are pressure reducing valves, set at a fixed outlet pressure.  That water is then distributed along pipes running down the roads with many hundreds and thousands of connections, supplying water to each individual property.

Meera -   We’ve got a mock up here in front of us which has a pressure reducing valve.  It’s about half a metre in length.  But above this, you've got small black device which is connected to the pressure reducing valve and is monitoring the pressure of the water  - both before and after this valve.  How does your system work to control the pressure of water that’s leaving this valve and reaching a distribution area?

i2O unit in situAndrew -   The system comprises a controller, which is an electronic device, which interfaces with the pressure reducing valve which controls the pressures in the districts.  There’s also a remote sensor or remote sensors which again are electronic devices, monitoring pressures.  These devices communicate over the internet to a centralised server.  The server processes their data, learns the relationships between pressures and flows, and sends instructions back down to the controller.  The controller uses these instructions to continuously adjust the pressure reducing valve, to vary the pressure constantly during the day, to maintain the minimum possible optimum pressures in the network.

Meera -   Within this controller itself - you have one here opened apart - it’s pretty complex in there.  There’s a modem in there, there’s a battery.  It looks extremely complicated.

Andrew -   The devices are really mini computers.  The biggest challenge for us was energy because these devices are fitted in chambers in the ground, in the roads.  There’s no opportunity to fit a solar cell and we’ve got to run these devices for, typically, five years.  So , the devices have a key requirement for minimum power consumption.  They run from a single battery which is roughly twice the size of a D-cell battery, and that device is then monitoring the pressures through (RPST) or Resistive Pressure Sensing Technology.  The devices are recording the data and then connecting to the internet through the GPRS connection and transferring the data  only when they need to.  The control device also has to control the PRVs through a special valve.  The valve also requires minimum power consumption to make the changes.

The i2O pressure controllerMeera -   What have been the results so far?  Has there been a reduction in water loss?

Andrew -   In the UK, we’re working with all of the major water companies now and we’re seeing an average leak reduction of 20%.  On a typical district’s metering area, comprising say, 2,000 properties, we’re seeing reductions of around about 60 to 80 cubic metres per day.

Meera -   Now an important part of this though is that their benefits extend beyond simply controlling the water loss...

Andrew -   Yes.  Water distribution requires water to be pumped from the water source to the trunk mains.  The pumping in the UK uses approximately 1% of the total electricity produced in the UK.  So by reducing leakage or reducing the quantity of water to be pumped, there is a significant impact on carbon being produced by those pumping stations.  We would be reducing the amount of chlorination that required at the treatment works.  Also, there will be fewer bursts which will reduce the social impacts of repairing the bursts.  So as you can see, controlling the pressure has a wide range of environmental benefits.

Helen -   That was Andrew Burrows, technical director at I2O, explaining to Meera Senthilingam how careful control of the water pressure in our pipes can lead to a dramatic reduction in the amount of water needlessly lost and wasted in urban water supplies.

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A civil engineer friend told me of one scheme that was in use a couple of decades ago: a collapsed 'tube' of pre-wetted glass-fibre was pulled through leaking drains (after they'd been emptied) and then inflated with compressed air until the resin in the GRP set, lining the drain with GRP.  However, he was at one site where this technique was being used when the 'tube' snagged and got stuck, and was still only half way through the drain when the resin went off...

They had to dig the whole lot up to get it all out. LeeE, Wed, 3rd Mar 2010

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