WATER LEVEL MONITORING
Learn everything you need to know about water level monitoring, how it works, and what you need to look out for when you are about to invest in your own system.
November 1, 2017

Remote monitoring brings accurate and timely measurement of nearly anything to your phone. This greatly reduces the high costs that have traditionally been unavoidable in this manual, but crucial task.

For example, stock water level checking is mandatory to ensure animals survive, especially in high temperatures. This exercise is costly in fuel and time for large, remote or unattended properties.

Water tank

The rapid growth in remote monitoring in many industries has led to robust, high volume, low cost solutions. The technology and products are now more mature than ever, bringing this capability out of the domain of large utilities and technology enthusiasts and making it a viable and profitable option for many businesses.

In agriculture, the need to track critical assets like water has always been essential. The costs to do so are significant and increasing. Remoteness, distance and terrain all contribute to fuel costs, time, and vehicle wear and tear. As water use rises in summer, the need to check water availability increases, the risk of running out of water is real and the impact more severe.

Today, low cost electronic sensors can monitor your assets around the clock, every day of the year, and more frequently than human labour.

What is remote level monitoring?

Remote level monitoring is the use of technology to remotely sense a level, communicate that level to a user who can then make decisions and take actions in a timely fashion.

This is different from remote level logging where technology is used to sense a level, save that reading locally so it can be retrieved from the site some time later.

Remote level monitoring is part of what is now being called the 'Internet of Things' (IoT) where 'things' (devices such as remote level sensors) connect to the internet. Remote level monitoring solutions bring together in-field level sensors, communications, remote power and smart user interfaces.

In this article we are going to look more closely at the key elements and discuss the choices available when purchasing systems, and the implications of those choices.

Level sensors

Level sensors measure the height of fluid. There are three main types:

  • Float sensors
  • Pressure sensors
  • Distance sensors

Float sensors

Floats are the simplest form of water level sensor. A buoyant object is placed in a liquid and generally used to provide a visual indication of the water level. A key drawback of such sensors is low accuracy and the need to physically visit the sensor to obtain a reading. Float sensors can be combined with a magnetic switch to create an electrical circuit which can be used to activate a pump when the water level exceeds a threshold. Float are not used for remote level sensing.

Float sensor image

Pressure sensors

Pressure sensors operate under the principle that the pressure exerted by water is proportional to the height (or head) of the water. The main type of pressure sensors are differential pressure gauges. These sensors sit in the water (at or near the bottom) and measure the difference between the pressure exerted by the head of water above and a reference pressure (atmospheric pressure in vented probes). The difference in pressure distorts a diaphragm which can be measured. These sensors are typically very accurate with error readings up to 0.1% of the full scale reading (5mm for a sensor with 5m range). Pressure sensors by their nature, must be immersed in the water and care must be taken to protect and maintain them and their environment.

Pressure gauge image

Distance sensors

Distance sensors sit above the water and send a pulse down towards the surface. The sensor measures the time it takes for the reflected signal to be received back at the sensor and converts this to a distance. Then, using the geometry of the tank and the position of the sensor, calculate the water depth. The pulses can be either sound (ultrasonic), radio frequency (RF) or light (laser). These sensors are typically very accurate with error readings up to 0.1% of the full scale reading (5mm for a sensor with 5m range). Distance sensors require the installation of the sensor to be directly above the water and not at an angle to the water as reflected pulses will not be received. Fortunately, many remote level monitoring systems that supply distance sensors come with easy to install mounting kits.

Ultrasonic sensor image

Which sensor should I use?

Which sensor to use depends on the application requirements and cost constraints. For most tank level and flume gate monitoring applications in agriculture, ultrasonic level sensors make a good choice. The measurement range, accuracy, and price make these sensors excellent candidates. For very tall tanks there are long range ultrasonic sensors that can reliably measure ranges up to 40 m. Ultrasonic sensors can also be used to measure levels of volatile fluids. Several manufacturers offer sensors that are designed for harsh chemical environments.

For applications with much greater range requirements, such as water bore measurements, vented hydrostatic level probes are more appropriate. They also suit measuring water levels in unstructured environments like dams and reservoirs. To avoid sediment build-up that may affect the hydrostatic probe’s performance, it is advisable to place the sensor inside an un-sealed enclosure, rather than directly on sediment.

Sensor Cost Accuracy Range Remote access Reliability Water contact
Floats $ Low Low No Medium Yes
Hydrostatic $$ High High Yes Medium Yes
Ultrasonic $ High Medium Yes High No
Laser/Radar $$$ High High Yes High No

Communications

Although communications options have not changed remarkably for some years, affordability has improved significantly. The choice of communications are worth understanding because they have a significant impact on both upfront and ongoing costs. The factors to consider are coverage, cost and reliability.

IoT devices generally transmit very little data, so transmission speed does not need to be high. Latency, which is the delay between a sensor reading and it being received, also is not that critical. This can be in the order of seconds, minutes or hours. Transmitting more often will be more costly in data and power use. What is important, is that the small amount of sensor data is successfully transmitted and reliably received.

The three most common communications solutions are

  • 3G/4G cellular networks
  • Satellite communications
  • Private radio networks

Mobile 3G and 4G

Wireless networks provided by the major mobile carriers such as Telstra are extremely reliable. Data over mobile networks is inexpensive. The biggest drawback of these networks is network coverage, particularly in remote areas. Quality antennas can be used to extend the range significantly beyond that of a typical mobile phone. There is are large selection of IoT devices that are ready for use with most mobile carriers.

Satellite

Communicating with satellites requires more specialised equipment than the other options. This results in significantly more expensive hardware. The satellites themselves have limited bandwidth so data costs are also higher. The biggest advantage of satellite solutions is that they have global coverage. For very remote installations they may be the only option. When weighed up against fuel and travel costs, satellite monitoring can make good financial sense.

Recent commercial interest in launching and operating micro satellite fleets appears to be a promising option to reduce data operating costs.

Local Private Radio Networks

There are many point to point local and private radio options available in the UHF, VHF, 900MHz bands. There is free, unlicensed spectrum available specifically for device communications. Point to point radio will allow deployment in most environments and does not need to rely on any external radio infrastructure. The advantage of this is that private radio networks can span into areas without any mobile 3G signal.

Designing and building private radio networks is a specialised skill that requires careful consideration of factors such as site selection, terrain, radio power and antenna selection/height/direction. With careful design and good equipment, some radio links can span over 50 kilometers. An important factor to keep in mind is that the operation and maintenance of the network then becomes the responsibility of the owner.

When using unlicensed spectrum, the cost of these networks is free. Local radio networks can be linked to the internet where it is available (3G, satellite) and have all the advantages that this entails (monitoring online, alerts to phones/email, data backup). If they are not connected to the internet then the remote sensor data will only be available at one of the radio end points, such as in the homestead/office.

Communications Hardware Cost Data Cost Complexity Coverage
Mobile 3G/4G $ $$ Low Mobile areas only
Satellite $$$ $$$ Medium Global
Local radio $$ $ High Custom

Power

In the majority of remote monitoring locations, mains power is not available. Therefore, field equipment must be power self sufficient. The power options are straightforward but the implications require some consideration.

Given there is limited power available remotely, solutions need to trade off power intensive work, such as transmitting readings, with how often they can be done.

Battery Only

Battery only equipment is cheaper, smaller and simpler because there are no solar panels or charge controlling electronics. Installation is generally simpler as well since the units are smaller and there is no need to consider solar panel orientation and shading. Maintenance is a matter of replacing batteries.

How long will my battery last?

It is first worth considering what your requirements are. How fast does the water level change? How often do you want to read the sensor and receive an update? Is this real time, every few minutes, hourly or less?

Battery only installations will read and transmit less often than solar installations as there is less power available. For example, the lifetime of a quality remote sensor battery is about 2 years with hourly sensor readings and updates of these readings sent every 12 hours. This is often adequate for most applications.

Solar

Solar installations charge an internal battery when the sun is shining on the panel. When it is dark or overcast, the system is powered by the battery. Most systems are designed with enough power reserves to power the system for a least a week without light. Some systems may begin to transmit less often as power reserves run down, extending the life of the remaining charge.

These systems are usually more expensive than battery only systems due to the solar panel and charge controller. Solar systems require more consideration when installing as they are generally bigger, the panel must be orientated correctly and not be subject to shading. There is little to no maintenance required other than cleaning the solar panel.

Power Upfront Cost Ongoing Cost Reliability Installation maintenance
Battery $ $ High Low
Solar $$ Low Medium Low

Interface

The interface presented to users of remote monitoring systems is one of the most crucial elements. After installation is complete, this is most visible and used part of any system. It must be simple and intuitive for everyday use so ensure that you've seen or tried out before buying. ​ Some of the considerations of the user interface:

Is it available online?

Online applications are available anywhere, anytime you have internet access be it on site, or anywhere in the country or the world.

Is it easy to learn and use?

A user interface should be simply and intuitive enough to use it without having to read a manual.

Can you use it on a phone?

Most of people do not carry around laptops when on site but do have their phones. Today, monitoring applications should be built specifically to be used on a phone.

Are there alerts on critical events? How are those alerts sent?

Alerts can notify users on critical events such as; water level too low/high, water level falling/rising too fast, battery low, no communications.

Is it secure?

Security in IoT applications is one of the most important considerations. Some important features to look out for include:

  • Only authorized users can gain access to the application.
  • The application must used the latest web encryption standards to safeguard against eavesdropping.
  • Your data is backed up and retrievable at any time.

Are the settings updateable remotely?

It should be easy to update settings such as alert level triggers through the user interface.

Is the information easy to find and understand?

It should take very few clicks of the mouse or taps and swipes on the touch screen to get the information your require. There is nothing more frustrating than endless menus, button, and dialogues every time you log on and want to get a quick look at your sensor data.

Is it easy to get help?

Ask your provider about getting support if you have support questions. What is the policy on warranty, repairs, and returns? What happens when anything stops working?

Can the user interface be shared with other users?

There may be multiple users of the system from site managers, on site help to owners. An interface that allows multiple accounts with different access levels (so not everyone is can charge the settings or billing profiles) allows for easy and secure access.

Is it expandable to multiple sensors?

Does the system scale easily if you want to add more sensors in the future? Will the interface still be easy to use? How hard is it to do this and are there any implications?

Why Remotely Monitor Water?

The benefits of remote monitoring versus manual level checking are significant:

  • Spend less time travelling to check tanks levels
  • Results in less fuel used so saves unnecessary costs
  • Know more about what ’i happening on site despite being there less
  • Catch critical issues such as leaks, blowouts, low levels much earlier and prevent more serious and costly consequences
  • Observe longer term level trends and gain insights on water use

The financial benefits of saving fuel, vehicle wear and time will often pay for a remote monitoring system in a short period of time.

Why Now?

Volume manufacture of these devices. No longer bespoke custom solutions meaning high reliability and lower costs. Declining data costs across mobile 3G and satellite services. Remote monitoring packages are now designed for easy use and not just for technical enthusiasts. Protect the water assets that you have now. Don’t wait until after the next critical water event.

Why 360Tanks?

We understand that rising input costs (fuel, time, labour) and water security remain critical concerns in your business. Let us help by monitoring your critical tanks and their valuable contents.

We are passionate about bringing proven automation technology to agriculture to make life easier. Let the technology do the manual work, increase your business's productivity and be more informed about your water.

With many years of experience in the agricultural telemetry industry in Australia, we firmly believe now is the time to use remote telemetry. The technology that has promised much before is now mature. It is being produced in volume by large, well established manufacturers and can deliver results both reliably and affordably.

360Tanks have sourced the most reliable hardware available and paired this with an easy to use user interface. Our solution uses an ultrasonic sensor, battery and 3G communications module to provide what we think is the best solution combination available for most tank level monitoring applications.

We know the technology, we know the industry and we are passionate about helping you be more productive and at the same time save water, fuel and time.