Monday, 5 December 2022, 4:42 AM
Site: Online Platform of Vocational Education - Water
Course: Frequently Asked Questions (POVE-FAQ)
Glossary: POVE-FAQ

Are there some basic methods how to calculate surface discharge?

Yes, one of the most basic is so called SCS CN method. The method was developed in US by their Soil Conservation services but recently serves as one of the widest used methods over the word. The method could be characterized as the empirical model of precipitation - run-off process of small watersheds. The abbreviation CN means curve number and every CN represent specific characteristics of the watershed. With the knowledge of real values of relevant watershed characteristics, the CN is obtained and used for surface discharge calculation.

Are there some significant proportional changes in water balance parameters of the forest watersheds in consequences of climate changes?

Yes, there are some significantly visible trends from let’s say 2013 showing changes in water balance parameters of forested watersheds in Central Europe. Generally, it could by claimed that the ratio between the evapotranspiration and discharge has started to change when there was marked decrease of discharge induced by the increase of evapotranspiration. For example, speaking about middle altitudes (so called uplands), we got the change of starting ratio 80:20 (evapotranspiration:discharge) to current 90:10.


Can drinking water have a specific smell or taste, such as chlorine?

Drinking water should not have any specific smell or taste. In some countries, chlorination is used in the drinking water treatment. Depending on the chlorine dose used, people may smell or taste chlorine. If the concentration of chlorine in the drinking water does not exceed 0.2 mg / l, then in such cases such a minimum amount of chlorine is not felt. If, however, you feel the presence of a specific odour, report it to the housekeeper, as this situation is not the norm and must be prevented! If you do not receive a response from your operator, contact your local water supplier. 


How do I know if the tap water I drink and use to cook is clean?

First of all, remember that water that is abstracted, treated, tested and delivered to consumers through drinking-water supply networks and via tap is safe to use, but that does not mean that it is completely sterile. If the water is treated using membranes and does not contain dissolved salts, then such water is called distilled water. The use of water purified in this way in the daily diet can endanger human health, as distilled water drain out salts in the body. The water that would be recommended for human consumption and provided through drinking-water supply networks contains various microelements and macroelements, such as Mg, Ca, K, Na, which have a beneficial effect on the human body. If the water from the drinking-water supply networks in your home is clear, with a pleasant refreshing taste, without a specific colour and smell, then you can be sure that the water is clean, safe and suitable for drinking. 

How do the sensors for water level measurements generally work?

There are two basic principles on which are water level measurements sensors operated. The first one is the hydrostatic pressure of water under the sensor. The second one is ultrasounds ray transmitted by sensor and receipted by it after its reflection by the water level. The first group of the sensors are of the submersion construction and is equipped by the pressure balance capillary to balance the unexpected changes of atmospheric pressure, the second one is constructive as pendant and must be fixed with some additional construction.

How is Cryptosporidium removed from raw water?

As Cryptosporidium is a protozoa which is pathogenic to humans measuring only 4 – 6 µm in diameter and are highly resistant to disinfection using chlorine then they are more commonly removed by conventional treatment processes such as coagulation, clarification, media (sand) and membrane filtration. Other treatment regimes include Ozone (O3) and Ultra Violet (UV) irradiation. Ozone and UV treatment do not actually kill the oocysts but inactivate the DNA thus disabling their ability to reproduce.

Given the dimensions of Cryptosporidium oocysts effective removal cannot be guaranteed by filtration alone. It is necessary to add a coagulant chemical to raw water that will ensure that the smaller particles, which can be up to several hundred times smaller than the grains of sand in the filter media, bind together through electro-chemical force attraction, forming what is known as floc. These larger floc particles can then be more effectively removed by the filtration process.

Micro-Filtration (MF) and Ultra-Filtration (UF) membranes are very effective at removing particles between 0.1µm - 10µm (MF) and 0.001µm – 0.1µm (UF). These filtration techniques are often used where the source water coming into a water treatment works is already of a high quality and will not require initial clarification. The disadvantage is that only high quality raw water will be effectively treated as membrane filters would become quickly blocked should the water be have high colour or turbidity.

How is possible to determine basic irrigation need of plants?

There are numerous methods which could be used to it but there is very easy one. In fact, just extend of vegetation season of solved plants, precipitation amount in this period and potential evapotranspiration within this period must be known. After comparing of the precipitation amount and potential evapotranspiration within the vegetation period of the plant we might get potential need of water of the plant.


Is the Legionella bacteria multiplying in plumbing? What is the risk of getting it if I drink water from a tap, maybe it is safer to use bottled water from a bottle?

Legionnaires' disease cannot be get sick by drinking tap water! Yes, bacteria can end up in plumbing there to live and multiply, but the danger can only arise if it enters a humans lungs, not the stomach. This can happen at a certain temperature, above +40 degrees of Celsius, when the water evaporates. So the risk of getting sick is by inhaling bacteria, taking a shower, ventilating and conditioning systems, not drinking water. From a safety point of view, it doesn't matter if you drink water from a bottle or tap! However, to reduce the risk of "catching" dangerous bacteria when taking a bath, drain the water at maximum temperature for at least 2 minutes before use! 

Isn't the water from the spring better than from the tap?

Unlike spring water, tap water is constantly monitored. Often we choose to drink water from a spring because, for example, it has good mineral indicators, its taste is very pleasant and we are convinced that the spring water is clean. And it is very possible that for the most part it is, because in addition to the good indicators, the water is in constant motion, which does not allow bacteria to multiply. However, spring water also has its own dangers, which are possible from nearby residential houses with, for example, a local decentralized sewerage system, as well as groundwater and agricultural pollution, etc. ! But we can learn to introduce something good into our home from spring water. It is a continuous flow- if you have not been at home for a long time and used water, make sure that the water that has slightly accumulated in the indoor plumbing is drained for couple of minutes. 


What are Apparent losses (AL)? What does it consist of?

Whilst Real Losses refers to the physical water losses i.e. the water leakages in the water distribution network and storage facilities, Apparent Water Losses (AL) refer to water losses emerging from the “non-billed” consumption of water. Vermesch et al [1], defines AL as volumes of consumption that reach consumers but are not billed. A. Rizzo et al [2], categorize AL into the following four fundamental elements indicated in Figure 1.

Figure 1

1.     Meter under-registration consists of the inability of a revenue water meter to accurately measure flows, especially the lower flows. This tends to increase with time and as the meter degenerates.

2.     Water theft is easy to conceptualize and consists usually of bypasses to the water meter, illegal connections, or willful damage to the water meter.

3.     Meter-reading errors consist of mistaken, or intentionally incorrect, meter-reading mistakes.

4.     Water accounting errors consist of billing anomalies, such as computer-based estimations, that do not reflect actual consumption values.


In his study on developing the Best Practice for Reducing Commercial losses, Loupos et al [3], claims that whilst utility companies focus on reducing Real Losses, AL is often overlooked and this can lead AL to be higher in volume than Real Losses. Furthermore, in most cases, AL is often attributed to meter under-registration.



1.     Vermersch, M., Carteado, F., Rizzo, A., Johnson, E., Arregui, F., Lambert, A. 2016. Water Audit Component Analysis and Best Practices. Guidance Notes on Apparent Losses and Water Loss Reduction Planning, 29–31. Available online at: (Accessed on 30 October 2017).

2.     Rizzo A., Vermersch, M., John, G., Micallef, G., and Pace, R. 2007. ‘Apparent Water Loss Control: The Way Forward’, IWA Water21 Journal, August.

3.     Loupos, K., Amditis, A., Bettin, A., Charalambous, S., Bazzurro, N., Fantozzi, M., Boubaker, A.,Beji, A., Gaber, A., Al Shafei, M., and Kounoudes, A. 2014.‘Cooperation Framework towards Efficient Water Resources Management–The AQUAKNIGHT Project’. Athens, Greece.

What are the categories of dams in the Czech Republic and how are they determined?

The water structures in the Czech Republic are classified in four categories, where loss potential in case of dam-break is the main point of view for the division of these categories. The level of safety surveillance and supervision on each water structure therefore depends according to potential losses on human lives and property in case of their breach. The determination of criteria and procedures for the classification of waterworks into categories is subject of special legislation, especially Water Act. Letter (P) stands for the potential of damages.

This is the definition for the categories, in which are the dams divided:

I. category -> (P) > 1500

II. category -> 200 ≤ (P) < 1500

III. category -> 15 ≤ (P) < 200

IV. category -> (P) < 15

What are the main causes leading to meter under-registration?

The use of private water storage or buffer tanks is a major contributor to meter under-registration. These challenges are further augmented in water networks such as Malta, where consumers use private water storage tanks to cope with irregular water supply. In contrast to a direct plumbing system, where water is fed directly from the main supply to the different outflow points (such as washing machine, flushing, water heater tank etc.), the use of private cold water storage tank creates an indirect plumbing system [1,2]. Cobacho et al [3], concludes that the bigger the surface area of the water tank, the lower would be the starting flow rate, hence, the higher the meter under-registration.

Water tanks on roofs tops are a major contributor to meter under-registration

Another major factor affecting meter performance (assuming appropriate meter sizing and no manufacturing faults) is meter age [5]. This result is reconfirmed by a local study [4], which found that domestic meter performance reduction (under/non-registration) was primarily attributed to ageing.


1.       A. Criminisi, C. Fontanazza, G. Freni, and G. La Loggia, "Evaluation of the apparent losses caused by water meter under-registration in intermittent water supply," Water Science and Technology, vol. 60, pp. 2373-2382, 2009.

2.       M. Fantozzi, A. Criminisi, C. Fontanazza, G. Freni, and A. Lambert, "Investigations into under-registration of customer meters in Palermo (Italy) and the effect of introducing Unmeasured Flow Reducers," Fantozzi% 20et% 20Al% 20Palermo% 20case% 20study% 20V4, vol. 20030309, 2009.

3.       R. Cobacho, F. Arregui, and E. Cabrera, "Private water storage tanks: evaluating their inefficiencies," Water Practice and Technology, vol. 3, p. wpt2008025, 2008.

4.       W. S. C. (WSC), "A Research project aimesat Improving the Water Metering Policy of the Water Services Corporation of Malta," Water Services Corporation (WSC), MaltaMarch 2017 2008.

5.       J. W. Male, R. R. Noss, and I. C. Moore, "Identifying and reducing losses in water distribution systems," Noyes Publications, Park Ridge New Jersey. 1985. 156, 1985.

What are the main purposes and benefits of dams?

Dam is a specific structure built across a stream, a river, or an estuary to retain water. Dams are built to provide drinking water for human consumption, for irrigating arid and semiarid lands, or for use in industrial processes. They can also be used to generate electricity as hydropower plants, to reduce peak discharge of floods created by large storms or heavy snowmelt, or to increase the depth of water in rivers to improve ship transportation. The upside is that dams can also provide a lake for recreational activities such as swimming, boating or fishing. Many dams are built for more than one purpose; for example, water in a single reservoir can be used for fishing, to generate hydroelectric power, and to support an irrigation system and as a protection from floods. Water-control structures of this type are often designated as multipurpose dams.

What does this Triple P mean?

Easy answer: People Profit Planet. Okay, so what does this mean then? Well, it means to say that these three groups need to be in balance. Everything we do should be in the best interest for the wellbeing of all people, taking into account the economy at the same time (without a healthy economy, company’s cannot work) and, moreover, the wellbeing of the Planet needs to be served at the same time as well. As mentioned, these three need to be in balance, in the sense that not one of them is more important than the other! Things are shifting, but the weight of Profit was for a long time overruling the People and Planet. Luckily, more and more people and companies start working toward an honest balance, working towards sustainability. The 17 sustainable goals are a good example, many companies and governments are starting to take these into account in their policy.

What is compensation water?

This is the quantity of water, generally referred to as the volumetric flow that must be discharged from an impounding reservoir. This is required to ensure that the natural river conditions downstream of the reservoir are maintained and that the rights of riparian owners, the flora and fauna and other parties who may abstract from the water course downstream of the reservoir are met.

It is important to ensure that the aquatic environments that rely on a consistent flow of water are managed responsibly. Large volume abstractions are therefore governed by regulators and as such a licence to abstract water must be applied for This ensures that the abstraction is limited thus allowing the good management of the environment downstream.

Some downstream aspects to consider are:

  • drying out of rivers and wetlands
  • variable flows of water below hydropower stations and water supply reservoirs may result in bare banks and stranded fish
  • low water levels in reservoirs can result in drying out of the shore line. This can prevent growth of plants and spawning fish
  • downstream sediment may be reduced in water bodies. This is required for fish and insect life and will change the ecological balance of the water course.
  • Reduction of downstream flow can mean that treated waste water discharge into the water course may not be as dilute as is required which in turn may affect water quality and aquatic life.

What is Cradle to Cradle?

Well, in this case, the word cradle in itself means ‘birthplace’, making this a perfect word for what cradle to cradle means. It implies a closed loop, for instance when a product is made, it can be used until it doesn’t function (well enough) anymore. It is then returned to the place of origin (where it was made) and completely recycled. All elements necessary for production is therefore produced and recycled at the same place. An example in water technology: Agricultural machines used for spraying plant protection products/ pesticides need to be cleaned. The water used for this becomes contaminated and should not be flushed through the sewer or flow to surface water. Therefore this water is captured and filtered using a biofilter, cleaning the water from pesticides and pathogens (coming from the fields). In this way the cleaned water is not spilled and can be used over and over again for cleaning agricultural machines. Pesticides will be in the biofilter, which will need to be replaced every now and then. The biofilter will be processed in such a way that it can be used again and chemicals/ nutrients coming out of the filter can be reused.

What is Cryptosporidium?

Cryptosporidium is a protozoan parasite often found in general watercourses, as well as raw water reservoirs. Many raw water sources are located in rural areas where sheep, cattle and other wildlife (deer, rabbits, foxes etc.) are present. The parasite can remain within the body of the infected animal, multiplying many times and then can be spread through the animal faeces onto the land. Each oocyst is on average 4 – 6 µm in diameter and can exist in water and damp environments for several months.

Not all animals or people infected by Cryptosporidium will display symptoms. However they will spread the parasite and the resultant disease, Cryptosporidiosis. This has fever like and gastro-intestinal symptoms and can be life threatening for the young, elderly or those with compromised immune systems.

As described above Cryptosporidium oocysts are found in areas where intensive farming and/or wildlife is present. Depending on soil types and geology of an area, precipitation falling on the land surface may infiltrate surface soil and percolate through sedimentary rock strata introducing Cryptosporidium into aquifers or rock fissures.

Where abstraction via boreholes is undertaken then compromised water quality will result, necessitating enhanced treatment to ensure complete removal of Cryptosporidium oocysts.

There are a number of ways to sample water for the presence of Cryptosporidium. The most effective being a sample of at least 1000L of raw water taken over a 24 hour period. Any evidence of Cryptosporidium oocysts in a sample may mean a failure in the water treatment process or more robust land and animal management in the catchment area.

What is dam safety supervision?

Dam safety supervision (shortly DSS) is monitoring and evaluation of the technical condition of the waterwork in terms of its safety, operational reliability, possible causes of failures and their consequences. It also includes designing effective corrective actions for specific events caused by wide sort of possible safety problems. DSS also helps preventing failures and possible economic damages not only on the waterwork itself, but also in the area below. The main goal is to prevent the threat to human lives and property, which could be caused by the dam break flood wave. DSS is therefore an integral part of the system for global flood protection and prevention against the dam breach that may occur during the operations of the specific waterwork. Dam safety supervision means periodic inspections, measurements and writing periodic reports with data evaluation, time series assessments and limit values check.

What is Non-Revenue Water (NRW)? What are the consequences of NRW?

Defined by the International Water Association [1], NRW refers to water which is not billed and hence, no payment is received by the water entity for its consumption. The obvious consequence of NRW is the adverse financial consequences for the utility company. Furthermore, significant NRW can lead to rising unmet water demands combined with requirements for more resources and operational expenses to supply additional water. Understanding elements of Non-Revenue Water are crucial for the good governance of the water supply system by a utility company. Non-Renevue Water is composed of Apparent Losses (AL) and Real Losses (RL).


1.     M. Farley, "Non-revenue water–international best practice for assessment, monitoring and control," in 12th Annual CWWA Water, Wastewater & Solid Waste Conference, 2003.

What is sustainability?

To be honest, this question can be answered in several ways, implying that there is no universal answer to this. In general sustainability is thought of like materials that last long, not one time use products. Mostly the concept of products made in an environmental friendly way is connected to this. However it reaches much further than this. Have you ever heard of the sustainable development goals? These describe in a broad sense, what is actually meant with sustainability (
It covers the world we live in, for all life, now and in the future. In Water Technology, this means that for instance we are working on safe drinking water for everyone.
This leads to innovation, developing new techniques to clean water, safe to drink. Waste water can be cleaned to surface water quality, safe for all life living in it. Therefore we need to filter out, among others, pharmaceuticals, heavy metals and pesticides. One new way of doing this, is by non-thermal plasma in direct contact with water to destroy dissolved organic pollutants. This makes it safe to return industrial water to surface water. To make surface water safe drinking water, membrane technology is taking a flight in making this sustainable. Sustainable in the sense of: low energy cost in production and use of the membrane, as well as durability.

What is the base flow?

Base flow might be defined in many ways but basically it is the streamflow which is remaining sustainably in the stream between the previous and following precipitation events. The base flow is the basic ecological parameter of the streamflow because it defines the streamflow which is long-termly available in the stream for water and surrounding ecosystems.

What is the difference between colour and turbidity in water?

The colour of water (usually measured in Hazen units can be as a result of both dissolved organic matter and suspended solids. Therefore to obtain a true reading of the colour of water a sample should first be filtered, normally through a 0.45µm filter. This will remove the visible suspended solids and leave any dissolved matter thus giving a true reading of the colour of the water.

The colour in untreated water is as a result of precipitation (rain, snow etc.) infiltrating soil as it falls on to the land surface. As it infiltrates the soil layers it absorbs organic matter from the peat and soil humus (in the form of humic and fulvic acids) and it is this that gives the raw water its distinctive yellow/brown colour.

This can be particularly noticeable during heavy rainfall events although it should be noted that there will be a need to differentiate between what is colour in the water and what is suspended solids giving it turbidity.

Turbidity is a measure of the overall quality of water. Turbidity is caused by materials in suspension although it is difficult to be accurate on a consistent measurement of this as particle size and shape will affect any reading. Fewer larger suspended particles can give a similar reading to a higher quantity of smaller suspended particles

The unit of measure is generally the Nephelometric Turbidity Unit (NTU) although an equivalent measure (the Internationally recognised standard is the Formazin Nephelometric Unit (FNU). Worldwide the most generally used unit is the Formazin Turbidity Unit. 

What is this “water technology” actually; what does it (not) include?

The sector Water Technology is large, in the sense that it covers a broad variety of subjects. It deals with technology making sure that are drinking water is safe to technology that makes wastewater safe to flow back into nature. Thus, dealing with clean fresh-water. Other technologies focus on the climate change, such as the shortage of clean fresh water, how to create fresh water from salt water and to do this in a durable way (not using a lot of energy and/ or chemicals for instance). But, there is more, how can you make use of salt to fresh water by getting energy out of it? How can we recycle nutrients from water?
What is not part of Water Technology are for instance subjects like how to build defensive structures (e.g. dikes) against rising water, of course this is technology and has to do with water, however is part of civil technology.

What kind of jobs are there/will there be in the future within and related to the field of water technology?

The field of Water Technology is very broad, meaning that there is a wide variety of subjects and disciplines involved. In general work can be done in Research & Development to applying techniques. Therefore, you can work for instance as an analyst, technician, researcher, project manager, engineer or sales manager. You can do these types of work in for instance, research institutions, company’s developing and or selling technology/ machines/ solutions and consulting agencies.

What measurement methods are used in dam safety supervision?

The subject of interest for the dam safety supervision is mainly the seepage regime and deformations of the dams and their subsoil. The seepage regime is monitored mainly by measuring the amount and turbidity of leaks at the outlet of drainage drains, on cracks and expansion joints, by measuring levels in observation wells, pressures in pressure wells and by using pore pressure sensors. Special deformation measurements include measuring on deformetric and clinometric bases, borehole inclinometric measurements, extensometers, pendulums and using geodetic methods such as very accurate leveling and trigonometric methods and other up to date geodetic methods such as ATR (automatic targe recognition). Temperatures of water and structure are measured as well.

What type of education should I follow to work in the Water Technology sector?

There is not a specific education teaching you to become a water technology specialist. There are some disciplines that will teach you skills which are necessary for finding a job in the sector. Such as, research skills and analytical skills, managing skills, engineering skills. However, the most important thing is, you need to have an interest in the water technology sector. Then you can find out how you can use your skills in this field

Where is the best quality of raw water generally found?

To understand why we need different treatment regimes for different sources of water we need to look at the differences in quality of the three main sources.

Raw water quality can be split into three source quality bands.

Upland surface impounded water, which is water that has fallen on high ground and run off and collected in reservoirs and natural lakes or lochs.

Lowland surface water, which is water in rivers, streams and includes springs.

Underground water, which is water in wells and boreholes

The quality of these waters will vary depending on the nature of the soil and rock strata through which they have passed and the extent to which pollutants have passed into them.

In quality terms, groundwater sources are normally the highest quality source, the next best being upland surface sources with lowland river supplies being poor or very poor since the water will very likely have had a degree of re-use and include, agricultural and urban run-off and sewage and industrial effluents.

The poorer the raw water quality the more complex and extensive will be the treatment required to bring it to acceptable quality.

Thus lowland surface water will generally require complex and extensive treatment in order to produce acceptable final drinking water quality.

Whilst upland sources can present quite specific problems, in general the degree of treatment required is relatively little to produce acceptable final drinking water quality.

By contrast underground waters can require very little in the way of treatment with often simple disinfection being the only treatment necessary.


Who is responsible for the safety of dams in the Czech Republic?

In the Czech Republic, the owner therefore the operator of the water structure is primarily responsible for its safety. He is obliged to perform dam safety supervision on the waterworks to prevent any technical and operational faults. It depends on the category of the dam, who is authorized to perform dam safety supervision usually for the dam owner there. If the operator does not have this authorization, he is obliged to hire an organization that is authorized by the Ministry of Agriculture to perform dam safety supervision on his waterwork.

With what other fields does water technology overlap and in what way?

Due to the fact that water technology has such a broad field of subjects and relating types of work, the discplines involved in water technology are many. Subjects like biology, chemistry, environmental sciences, biomedical analyst, chemical analyst, process engineering, chemical technology, civil engineering, policy and management, are examples of disciplines working in water technology.