What is a smart water meter?

What is a smart water meter?

If you wonder what is a smart water and what is the applicability of smart water metering and monitoring to your business read that post.

What is a smart water meter?

There are many definitions about smart meters and in particularly smart water meters.

Bellow are some of them:

by Thames Water

Smart water meters allow you to automatically track the amount of water you use, giving you greater visibility and control over your usage and water bill.

by Sensus

Meters are often viewed as the cash registers of a water utility, but advanced meter technology lets you do more than manage billing and consumption.

by ThingsLog

A water meter able to read, record and transmit over a wireless or wired network consumed water on frequent periods. The smaller the record and transmission period the better. In addition to that, some smart water meters could detect events such as a permanent or high consumption, backflow, tamper and send instant alerts.

Bring together the utility, the property owner and the household

To add a bit more smart water meters are devices that could bring together the utility, the property owner and the household by showing to all of them the same data (we call it consumption profile).

Once the profile is available to all parties it is also clear how the household has consumed, are there any leaks and eventually how much the consumer has to pay in the end of the month.

The main benefit of smart metering is that nobody will come to do manual metering which saves a lot of human resources typically wasted in the monthly or annually manual metering process.

If smart water metering is applied on the main water meter in the building the “water budget of the building” could be determined.  Based on the combined information from the apartment meters and the main meter the property owner will be able to determine the total water consumption and the amount of leaks happening into the building.

Smart water consumption profilingmobile consumption app

Consumption profiling together with an end customer mobile app.


Evolution of smart water metering

Water meter manufactuers have evolved a lot through the years. Initially  smart water metering has been based on mechanical water meters with a pulse output and a data logger able to do pulse counting.  The name of this combination is retro-fit. Retro-fits makes the dull water meter a smart one with minimum efforts.


First option is to be used a generic data logger for pulse counting of an existing water meter.

Retro-fit smart water metering

Above is an example of a mechanical water meter and ThingsLog low power data logger. This is still the most popular way to achieve smart metering in the world today.  The advantages of the retro-fit are that you don’t need to reinstall the meter and you are meter independent. The data logger could be easily moved from one water meter with pulse output to another.

Pulse outputs are also widely available and as a base each water meter manufactuer is producing such one for their meters. As a rule of thumb data loggers are also typically much more capable versatile and flexible devices than the click-on modules and true smart meters. They have the advantage of replacable batteries and ability to interconnect multiple water meters to the same logger which can’t be stated for any of the other solutions.

Click-on module

Second option is to put a click-on module specially designed for your water meter.

Water meter with a click-on

Click-on modules are typically designed by the water meter manufacturer and are one of the most common solutions for smart water metering. The advantage of the click-ons are that there are no cables, no pulse outputs and that you still don’t need to reinstall the meter in order to jump into the smart world. The disadvantages of most click-on modules are that they are limited  to the particular water meter model (ideally to manufacturer), one click on works for one water meter (so if you have two meters next to each other you have to buy two of those). Finally, most of the click-ons on the market are rather dull devices without replaceable batteries and in general are not really suitable for water consumption monitoring. Although they are perfect for metering and monthly billing. Typical click-ons modules are with wireless mbus and can transmit data only locally on a few hundred meters. Recently some manufactures announced click-on modules with LoRa and Sigfox which are suitable for long range communication and thus capable for real remote meter reading.

Final verdicts is that if the module support with some alarms (leak detection, tamper, freeze, reverse flow) that makes it a good and affordable solution for many use cases.

True smart meters

True smart meters have build in ability to record, analyze and transmit wirelessly their readings on configureable intervals of time. In addition to that smart water meters have new design, ideally are ultrasonic and much more accurate than the mechanical meters.

Finally a true smart water meter has a build in ability to analyze the water consumption and environment and supports various kind of alarms suitable both for the household, for the property owner and even for the utility operator.

2x Axioma W1

True smart meters are the best choice for new projects or in case  changing the meter and installing a new one is an option.

Choosing the right smart water metering approach?

The decesion on choosing should be based on certain criterion. Bellow is our breakdown.


Smart water meter certification is maybe the most important criteria for choosing and installing a water meter in general. The water meter has to comply to the directives applicable in your country.

Smart water meters are electronic devices that have to comply to certain directives directives and laws. For Europe to have a CE mark the meter will need to comply to at least (LVD, EMC and MID directives). For US to FCC. Similar requirements apply also to other countries. In addition to that there are country specific hygenic approvals. Examples are WRAS for UK, KIWA for Nederalnds, KTW in Germany. In many European countries MID is sufficient since it specifies the materials from which the meter has been produced.  Materials like bras, steel or composite are considered safe for use in potable watter.

Network communication

Smart water meter should be able to transmit its data readings and alarms to a remote system for further analysis and processing.  There are a couple of options this to happen:

  • Wired communication – typical choice is wired mbus, where the mbus master is providing power to mbus slaves (the meters). Mbus master could read registers on the slaves and that way to obtain the readings
  • Short distance wireless communication – typical choice is wireless mbus. This requires every month somebody to pass by the meters and to try to collect their readings over a wireless mbus master device. Since than the readings has to be transferred to the system. That approach is not suitable for monitoring.
  • Cellular communication – 2G, 3G, 4G, NB-IoT all that options are possible and good choice for the purpose. There are many data loggers supporting that way of communication. However, there is a very limited choice of water meters supporting directly any of the approaches. If possible, the preferred technological choice should be NB-IoT since the technology has been designed for low power communication and has better coverage.
  • Long distance IoT wireless communication – LoRa/LoRaWAN, SigFox, Weightless-P – among those are the best and most suitable and affordable options for remote smart water metering and monitoring. There are community networks like TTN and Helium and payed country dependent options offered by telecoms or IoT Operators. In the end, there are also open-source alternatives such as Chirpstack and any building owner could buy and own a few LoRa gateways.

Battery life

Battery life is always a factor in low power communications. Same is with the smart water meters. Ideally the smart water meter should achieve 10 years. There is always a tradeoff between the frequency of reading/transmitting data and battery life. So you should really look for the ideal ratio between those two. E.g number of readings/records being transmitted, number of transmissions compared to the total battery life.


Accuracy is important factors as well. For water meters it is measured as R the ratio between Q3 and Q1. Mechanical water meters could achieve up to R200 where ultrasonic could do much better up to R 800.


Smart water meter Is a criteria for the applicability of it to certain use cases. Here we distinguish between 3 key features:

  • smart metering (the base minimum – ability to get the daily/monthly consumption)
  • monitoring (ability to create a consumption profile)
  • alerting (ability of the meter to signal for certain events).


Last but not least cost factor for smart water metering is important. It is a good practice to do a Total Cost of Ownership analyis for the expected period of lifetime of the meters. In that one you should consider the cost for the meter, compared to the costs for manual metering, the network cost, the cost for a platform and customer mobile app.

As a rough estimate for an apartment water meter you should look for arround 50-70 Euro per smart water metering point as an inital investment if you need monitoring and for a price < 50 Euro per meter if you just need a click on or you can do it with a single data logger.

Smart water meter reviews

Finally we have build a couple of smart water meter reviewes based on the criteria above.

Hope you have found that article useful. If so please share and enjoy.

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