Water guide

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Water guide - An assessment of the health impacts of water quality addresses the potential microbiological health risks of drinking water. These microbiological risks are due to the contamination of raw water with microbes that cause potential health problems for people using tap water, as well as the efficiency of drinking water treatment, which can be insufficient for removing harmful microbes from drinking water. The assessment will be used to determine, how high the health risk is from certain microbes in raw water. The assessment is based on a mathematical Water guide -model, which can be found below.


How to assess the microbiological risks of drinking water as well as their health effects? Information of water treatment plants must be possible to use as raw data.



Classification of raw water:

Size of the exposed population:

The amount (in liters) of unboiled tap water consumed per person per day:

Microbe concentrations of raw water

Campylobacter concentration (microbes/l):

E.coli O157:H7 concentration (microbes/l):

Rotavirus concentration (microbes/l):

Norovirus concentration (microbes/l):

Sapovirus concentration (microbes/l):

Cryptosporidium concentration (microbes/l):

Giardia concentration (microbes/l):

Water cleaning: Cleaning process and chlorination

Water cleaning methods in use:
Coagulation and flotation
Slow sand filtration
Limestone filtration
Active carbon filtration

Chlorine dose (mg/l):

Ozone dose (mg/l):

UV dose (mW/cm^2):

UV time (s):

+ Show code

The result page opens in a new tab by pressing the Run model -box. It will take approximately 40 seconds for the model to run, after which the results will appear on the result page.

User instructions for the Water guide -model

1. Choose classification of raw water

  • Ground water - Clean: clean ground water
  • Ground water - Surface water load: f.ex. shore infiltration
  • Surface water - Low load: relatively clean surface water
  • Surface water - Medium load: f.ex. low waste water load
  • Surface water - High load: f.ex. waste water load


Choose 'I will determine microbe concentration by hand'. Write pathogen concentrations in their respective boxes.

2. State the concumption of drinking water per 24 h in liters per day per person (default 1.153 l/d).

3. State the population size of target area. (default 100000)

4. Choose treatment processes used. Obs! You can choose multiple options. If none of the first six treatment processes are used, choose "None of the above cleaning methods". If neither UV nor ozone is used, choose "None of the above disinfection methods".

5. Choose whether chlorination is used or not by giving the chlorine dose used (mg/l). If there is no chlorination, the dose will be 0 mg/l (default 0 mg/l). The model only calculates the effect of chlorine on the water in treatment plants, and ignores any further cleansing effects residual chlorine may have after the water moves onward to the pipe network.

6. You can see the results in a new tab by pressing 'Run model' This opens a new tab, in which the results will appear after the model is done running. This takes approximately 45 seconds.


Water guide.png

The model has been translated from Analytica to R. You can find the original model here (page in Finnish, link to the model code at the top): op_fi:Tiedosto:Vesiopas.ANA. If the user does not give concentrations for the pathogens, the values on page Pathogen concentrations in raw water will be used.

Health-based quality requirements and recommendations have been implanted on the quality of household water. In Finland, the ministry of social affairs and health is responsible for the legislation of the quality, and monitoring it is the responsibility of municipal health protection officials. Upholding and developing good water quality require high-standard research and cooperation between different parties. Ground waters and artificial ground waters are usually not disinfected. The chemicals and microbes in raw water and byproducts of disinfection produced in household water production can present health risks to the people using the household water. Water leaving the treatment plant can stay in the pipes for a long time. If the circumstances are favourable for microbial growth, the water can become low in quality and even detrimental to health while in the pipe network.

Household water is produced from either ground or surface water. The problems of these types of waters as raw water are different. Using surface water always requires establishing an actual treatment plant and the associated knowledge, skills, technologies and educated monitoring personnel. Ground water on the other hand doesn't require very complex treatment, so not many treatment plant personnel are needed, and there is less monitoring. Additionally today there are many treatment plants that produce artificial ground water. The qualities of artificial ground water can be similar to good ground waters, but the quality of the water is often only be equal to medium quality surface water.

Treatment of ground water usually includes increasing the pH and and hardness of water. This can be done using different techniques, of which the use of calcium hydroxide and carbon dioxide to regulate pH are the most common. Sometimes also precipitation of iron or manganese is required using strong oxidisers such as permanganate or chlorine. Low quality ground water is also disinfected.

In order to make surface water drinkable, it has to be heavily treated. The hardest thing is to precipitate the humus. This is done by using not only different precipitation chemicals, also for example adjust pH and breaking down the humus with strong oxidisers such as ozone. On top of that, the precipitated chemicals (such as salts of aluminium and iron) need to be removed and water hardness raised so that the pipelines don't disintegrate over time. Also, the population has to be protected from the microbes always present in surface waters, so the water needs to be disinfected to remove pathogens.

The quality of water is also affected by the condition of the pipelines and the water spends in them. If there is a lot of coagulation in the pipelines, these dregs include not only different inorganic compounds but also a large amout of bacterial mass. The coagulates in the pipelines and their qualities have started to be researched in Finland only recently.

The purpose of risk assessment is to produce information of the true size of the risk for decision-making. Risk assessment is a scientific process in which experts hold a key role. Because there are any kinds of risks to study, risk assessment processes can be very different. In environmental health risk assessment consists of four steps:

  1. Identifying the danger (does the variable researched pose a danger to humans?)
  2. Assessing the exposure-response function (how big a dose results in how big a response?)
  3. Assessing exposure (how much are humans exposed?)
  4. Characterising the risk (how high is the health risk?)[1]

All water treatment plants should periodically do risk assessment on on the household water they produce. It is done to identify actions to be taken in different crisis situations and prepare plans for different problematic situations and possible damage. Different treatment plants and for example vacation centers need different kinds of plans and implementations.


Pages containing the data and codes used by the model
Page What data or code the page has What is it used for Other observations
Op_en2949 Population of Finland Data on the age distribution of Finns Age distribution is used, because susceptibility to diseases and their severity changes with age. The burden of disease and cases of illness are calculated for each age group, then summed.
Op_en7956 Drinking water chlorination efficiency Log-decrease in pathogens due to chlorination, with different doses The code on this page uses the data on the page and user-given dose for chlorine to calculate the case-specific decrease in pathogens due to chlorination. This is summed with log-decrease of other treatment and disinfection methods to produce the total log-decrease in pathogens from water treatment. The model only takes into account any decrease in pathogens that happens in water treatment plants. Any further effect residual chlorine has after it enters the pipes is not included.
Op_en7955 Drinking water disinfection efficiency Log-decreases of pathogens due to ozonization and UV If the user has chosen one or both of these disinfection methods, the decrease from the chosen one(s) is summed with the decrease due to chlorination and other treatment methods to produce the total log-decrease in pathogens from water treatment. Currently the qualities of water, such as turbidity, are not taken into account in the efficiency of disinfection methods. The dose for both methods is also set.
Op_en7954; Drinking water treatment efficiency Log-decreases of pathogens due to different treatment methods. These methods are traditional cleaning, well working cleaning, enhanced cleaning, slow sand filtration, limestone filtration and active carbon filtration. If the user has chosen one of multiple of these treatment methods, the decrease of pathogens they produce is summed with the decreases due to chlorination and other disinfection methods to produce the total log-decrease in pathogens from water treatment.
Op_en7953 Pathogen concentrations in raw water The concentrations of pathogens of different raw water classes If the user has chosen one of the raw water classes, the amounts of pathogens in that class and the total log-decrease of pathogens from treatment are used to calculate the amount of pathogens left in drinking water. If the user has given pathogen concentrations by hand, those values are used instead of the data on this page.
Op_en7947 Case burden of waterborne microbes Case burdens of different pathogens, or how severe and long-lasting the diseases caused by them are This data is used to calculate the health detriments caused by the pathogens in drinking water.
Op_en7957 Health impacts of waterborne microbes Doesn't contain data, only code These codes use water consumption given by the user, total decrease in pathogens and the pathogen concentrations in raw water to calculate the exposure to pathogens experienced by one individual, or how many of each pathogen an individual swallows daily with drinking water.
Op_en7948 ERF of waterborne microbes Describes the exposure-response functions for the pathogens These functions tell, how likely an individual is to get sick with different exposures. This and the exposure are used to estimate the cases of illness.
Op_en2261 HIA Code that combines all of the above The code on the page uses exposure, exposure-response functions and the case burdens to calculate the total burdens caused by pathogens in drinking water. From here it is also possible to calculate the number of people getting ill from drinking water. These are the final results of the model.

Table of decisions used in drawing plotly graphs.

1AdjustGround - noneRawConcentrationRawWaterClass: Ground water - surface water contaminationRemove
2AdjustGround - noneRawConcentration

Well, this doesn't work at all.


Initiate model

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Plotly test

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Another plotly test

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Plotly with two sliders

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See also

Municipality-specific data


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