Saturday 15 July 2023

Smart meter for detecting water leaks

Many of us now have smart meters for electricity and gas, but we are starting to see smart meters for water too. They may help you with reducing water use – which is very important because of climate warming as well as the growing population. However, one of the key benefits is going to be detecting leaks – for water companies and for consumers. We had a water leak a few years ago and we would have spotted it a lot quicker if we had a smart meter!

We take water for granted and don't think about it. Smart water meters will help us track our use and detect leaks.

What is a smart water meter?

Smart water meters usually have similar features to smart energy meters so they record how much you use, often hour by hour, and send the readings to your water supplier (or their agent). This means there is no need for a man to come and read the meter in person and you can get much more frequent updates as to how much you are using. Southern Water is trialling a clip-on device that fetches readings from the old meter and sends them wirelessly to a datacentre [1]. In Coventry and Warwickshire, Severn Trent is testing new meters that allow you to check your consumption hourly if you want [2]. Anglian Water is rolling out something similar for all customers [3] and so is Thames Water [4]. They aim to have most customers on the system by 2030. 

Water meters are compulsory in some areas.

Ideally (for the water company at least) everyone should have one. However currently, in most places, having a water meter is up to the customer to choose. If you do not want to be metered, Anglian Water says they will give you a smart meter anyway and your bills will remain the same while Thames Water will automatically switch you to metered billing one year after the meter is activated. In the meantime they will give you comparisons of what the cost would have been compared to your current bill. 

Water companies are allowed to make water meters compulsory if they are in a water stressed area. However, only five companies, including Thames, are actually doing this [5]. Cambridge is not among them, although this is a water stressed area. Perhaps this is because we have a high proportion of customers on meters already. Thames has only about 50% on meters so far.

Water companies have targets to reduce water consumption to protect the environment, and to ensure that there is enough as the population grows. DEFRA's national plan [11] is for no more than 122 litres/person/day (average) by 2038. No water company has achieved this but some are getting near. In the latest figures on Discover Water [10], Yorkshire water was already down to 128. However, the average was 145. Four of the five companies that are making water meters compulsory had higher than average water use: Affinity (162), South East (156), SES (153) and Thames (148). In Cambridge, our use was a little less than average (140).

Smart meters make leak detection much easier.

Water companies know very well how much water they put into the system. Most of this water gets to customers and the rest leaks, but without knowing how much customers take out it is hard to be sure about how much is leaked. With the old meters, each customer gets a reading every six months which is good enough for estimates but not for accuracy or timely leak detection. Smart meters allow them to know how much customers have used on any one day, or even hour. Combined with some network analysis as to how much goes where this allows leakage to be identified and localised.

The overall UK leakage level is about 23%. This is middling for European countries [8]. Leakage in the UK is normally reported either per customer or by length of pipework. Average per customer leakage as of 2021/22 was 113 litres/property/day, varying from 65 at Bristol up to 152 l/p/d at Thames - by far the worst [10].

Customers have leaks too.

Water companies are responsible for leakage up to the meter into the property. After that it is our problem. A few years ago we had a major leak in pipework under the suspended floor ( see My Flood Story). We did not notice it for months, by which time there was considerable damage; with a smart water meter we would very likely have been notified by the water company within days.

Smaller leaks are very common. The most common problem in the home is a toilet with a button activated flush, where the cistern leaks into the toilet bowl. This is usually because a valve is not closing properly. It has been estimated that 5% of homes have a leaky loo. If you are metered, this could double your bill [9]. 

With smart meters Anglian Water reduced customer leaks by 85%

Anglian Water is in the vanguard for smart meter rollouts, having started in 2018. The area is acutely water stressed (even more than Cambridge). Both leakage reduction and demand reduction are key to their water resource management strategy. Doug Spencer, head of smart metering, appears on this video (about 18 minutes in) talking about the benefits they have achieved through smart metering. The chart below, pulled from the video, shows the volume of extra work generated by identifying leaks in customer service pipes and customer plumbing. He estimates that customer side leakage in the areas where smart meters have been rolled out has been reduced by 85%, amounting to 19 litres/day/property.

Still from the video  (CIWEM) Smart water metering: unlocking the benefits  showing how smart meters have enabled Anglian Water to detect more leaks

Smart meters are more expensive to install but OFWAT is sufficiently convinced of their advantages to approve seven water company schemes for smart meter rollouts ahead of the next planning period [11].

Smart water meters are possible now because of battery improvements.

Smart meters for water have been a long time coming, mainly because of the difficulty of getting power to them. Smart electricity meters are easy because they can use the electrical supply they are measuring. Gas meters are usually partnered with an adjacent electricity meter which does most of the work. The gas meter has to run on a battery, but it just measures the gas and tells the electricity meter every now and again. This means the battery can last a long time – hopefully as long as the meter.

Water meters do not have access to the electrical grid for power. Plus they tend to be placed on water supply pipes which are underground (mine is below the street under a manhole cover); this makes wireless communications difficult.

I am told these challenges are solved with modern, longer lasting batteries, by putting the wireless antenna as close to ground level as possible and transmitting data slowly which means it can be done with less power.

Conclusions - smart meters are key for network efficiency

Both smart energy meters and smart water meters bring significant benefits to many customers. Smart meters allow fairer billing when you are billed for what you use - because they give you a better understanding and control of your usage. They make it easy to spot leakage. similarly with energy meters you can identify the background loads that are otherwise pretty much invisible. (I was shocked when I found out how much gas is used by the pilot light on our gas fire.)

At the network supply level, smart meters benefit the water company by providing data for detecting leakage and other critical network performance statistics. Hence Anglian Water's goal to give every customer a meter even, even those that wish to continue on unmetered billing. 

We must reduce our water consumption to protect nature and to protect agains the impacts of climate warming. The national target is for a 15% reduction by 2030. How are we to  get there if we don't even know what we are using?

[1] Making meter reading smarter (Southern Water) Sep 2022

[2] Wonderful on Tap (Severn Trent Water)

[3] Smart Meter Upgrades (Anglian Water)

[4] Compulsory Meter is our region (Thames Water)

[5] Demand Reduce Solutions (Thames Water) 

[6] CCW statement on compulsory metering (CCW) Feb 2022

[7] Retail services efficiency review 2022 Report for Ofwat (OFWAT) Dec 2022

[8] Leakage in the water industry (OFWAT) Nov 2022

[9] What to Do About Leaky Loos (WaterSafe) 

[10] Find out how water companies in England and Wales are performing (Discover Water)

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