Oil in Water Monitoring: The 7 MUST HAVES


The continuous increase of the risk associated with water source contamination (rivers, lakes, aquifers, boreholes, reservoirs) means that more water companies are looking for an effective way to detect oil in water contamination at their intakes, or indeed, other chemical and hydrocarbon pollution.

While there are various technologies and approaches to this problem, it is important for operators to focus on some important characteristics that an oil in water analyzer should have, irrespective of the technology employed.

MS1200 Touchscreen Version

In the list below you can find a summary of the main characteristics that an oil in water detector should offer.

  1. Comprehensive Monitoring
  2. Immunity from high turbidity and mineral content
  3. Low limit of detection
  4. Low cost of ownership
  5. High reliability, low maintenance
  6. Continuous measurement
  7. High class service and support

Operators, looking for such solutions, usually search for:

  1. Oil in water analyzers and monitors
  2. Hydrocarbon monitors and analyzers
  3. Pollution event monitors
  4. Total VOC monitors
  5. Early warning systems for intakes

Let’s now look at these points in detail.

1 - Comprehensive monitoring

An oil in water analyzer should pick up the widest possible range of compounds.

When looking for contamination at a water intake, we cannot know for certain where the contamination is coming from and what kind of hydrocarbons there are in the water. This means that the technology we select should provide a wide spectrum to allow us to answer the question:

“Is this water good for production? Yes or No?”

There are different kinds of hydrocarbons and these are divided into: aliphatic, aromatic and polyaromatic hydrocarbons (PAHs).

When looking for an oil in water analyzer, you want to select a technology that is not specific for a certain kind of hydrocarbon (e.g. specific for PAH), but generic, and that will allow you to monitor aliphatic, aromatic and polyaromatic hydrocarbons.

For this reason, when designing the MS1200 oil in water monitor, Multisensor decided to use a wide spectrum technology.

Also, we should remember, that while certain compounds are more dangerous than others to humans, when looking for an early warning system to monitor the water intake of a WTP, what is usually needed is a comprehensive system that detects as many compounds as possible.

Various technologies (i.e. GC-MS) that look for specific compounds will have what’s known as a Low Detection Limit (LDL), which means a level below which, a compound is not detected. For example, the LDL for Compound A could be < 3 ppb, for Compound B < 1 ppb and for Compound C < 2 ppb and the values will be reported either as ZERO or Below Limit of Detection.

This means that, in theory, there could be a pollution event with a variety of compounds , that are all below a certain LDL, but the total could still be quite high.

For this reason, the MS1200, has been conceived as a Total VOCs monitor which is a very robust and reliable way to detect hydrocarbon contamination in water sources.

2 - Immunity from high turbidity and mineral content

The second most important characteristic for an oil in water analyzer is that it should not be affected by turbidity .

River water can present high levels of turbidity, as can boreholes with high mineral content, which can be problematic for optical based technologies. These technologies rely on filters and cleaners which need to be maintained, cleaned and replaced.

Also water can have a high level of minerals such iron and manganese, which can create build-up on sensors that have to be in the water.

Again, the MS1200 was designed with this in mind and it relies on a contactless headspace analysis, which means that the sensor never touches the water, so it is not affected by the turbidity and does not need to be cleaned.

3 - Low limit of Detection

While larger spills and accidents (ppm levels) are those that usually end up on the news, there is a growing awareness of the effects that certain hydrocarbons can have on health, even at very low concentrations .

For example, benzene, should always be below 5 μg/L according to regulations in many different countries and, given its carcinogenic effects , the target is to have 0 μg/L of benzene in water for human consumption.

For this reason, drinking water treatment plants, need to be able to detect low concentrations of hydrocarbons in water, especially BTEX (benzene, toluene, ethylbenzene, xylenes).

To achieve this, the MS1200 is calibrated using toluene, over a range of up to 200 ppb for most applications. This gives the operators the accuracy they need from an oil in water monitor at low concentrations and the ability, for example, to set a low level alarm at 20-30 ppb and a high level alarm at 50-60 ppb with confidence in the readings.

4 - Low Cost of Ownership

Most instruments are competitively priced in terms of the initial purchase price. The total cost of ownership also includes ongoing maintenance, spare parts, reagents and downtime.

Multisensor minimizes the cost of ownership with high reliability, low cost of spare parts and being free from reagents, chemical or gases to operate.

5 - High reliability, low maintenance

Water intakes are usually not manned since they are located remotely, next to a river, reservoir or borehole. This means that the analyzer needs to require very little maintenance and be very robust. The MS1200 is designed to be robust and to require only a service every 6 months which includes the replacement of some filter elements, some checks and an optional validation of the system.

6 – Continuous measurement

In order to respond quickly to any contamination event, an oil in water monitor should be able to measure continuously giving immediate information to the operators to protect their WTP, their assets and their reputation.

7 – High class service and support

Last but not least, analyzers usually need support: before installation to make sure that the application is properly assessed, during installation to make sure that the ideal conditions are met and after installation for maintenance and data analysis.

With a network of more than 60 distributors around the world, an helpful technical and support team and a long experience with hydrocarbon monitors, Multisensor Systems can support you and your instrument wherever you are.


Multisensor Systems technology has been protecting water treatment plant intakes for more than 20 years with the first installation done in the North of England in the early 2000s where a WTP wanted to protect its activated carbon filter bed from accidental hydrocarbon contamination.

Since then, Multisensor System has installed hundreds of units all over the world detecting contamination, measuring hydrocarbons and protecting people and assets.

For more information, please visit the MS1200 oil in water monitor page.