Posted on Monday, July 16, 2018 by Kristan Rokkjær
Reducing consumption-dependant water loss
A major challenge facing water utilities today is not having enough information about what’s going on in the distribution network. But there don’t have to be any secrets. At Kamstrup, we believe that a completely transparent distribution network and updated underground situational data are key to addressing this challenge. We want to share our vision and insight with you. Therefore, in this series, we move closer to the future in terms of Smart Districts (district metered areas) and inform you of solutions for minimising loss and optimising operations and – especially – product quality. In this third and final part of the blog series, we have a closer look at how data from pressure sensors can reduce the consumption-dependant water loss.
Pressure measurements in Smart Districts
In the second part of the blog series about Smart Districts, we described how the manager of a water utility categorises water loss as depending on either leaks or consumption. In the following, we will take a closer look at the consumption-dependant water loss which can be divided into two causes. One is that the water loss increases with the consumption due to consumption from unmetered installations that can be either unauthorised or defectively installed.
The second reason for consumption-dependant water loss is that the accelerated water flow in the distribution mains in high consumption periods increases the resistance in the pipes, causing the pressure in certain areas of the grid to decline. This reduces the loss from undetected leaks in the supply grid, creating a correlation between consumption and loss.
It is interesting to know the pressure in each individual district because pressure management is one of the most cost-effective ways to limit the water loss in districts where the water loss does not relate to the consumption, i.e. where it must be assumed that there are leaks in the system.
Reducing water loss through pressure management
In districts with little relation between water-loss and consumption, the loss will often be closely connected to the pressure. This means that you can reduce the water loss in that district if you are able to lower its average pressure. The challenge of reducing the pressure is both that many consumers consider pressure a quality parameter and that excessively low pressure heightens the risk of the ingress of contaminated water.
In order to efficiently manage a district’s pressure, i.e. keep the pressure at an ideal level at all times, it is necessary to know the pressure at several points in the district. A district’s topology often means that the pressure at the point of inflow does not necessarily provide an accurate picture of the entire district. The correlation between consumption, flow speeds and pressure drops also means that it is not always possible to point to a specific area in the district as the most critical in terms of pressure, as the pressure can change concurrent with changes to the district’s consumption pattern.
A utility manager who wants to have adequate basic data on which to manage pressure effectively needs to measure the pressure at several different locations in the district. In return, efficient pressure management typically reduces water loss markedly and saves energy due to the lower consumption of electricity by pumps.