1. Introduction
One of the most important factors influencing the quality of life is health, i.e., the state of physical, mental and social well-being. To achieve a good health state, it is necessary to meet numerous conditions, including economic and environmental factors (e.g., access to good quality water, terrain, weather conditions) [
1]. Sustainable urban development is one of the most serious problems of the 21st century [
2,
3]. Moreover, such development would not be possible without the ability to use water resources for drinking or industrial purposes in some regions [
4]. According to Sustainable Development Goal 6 (SDG 6), access to sustainable water and sanitation should be provided to all people by 2030 [
5]. However, the fact is that, in many countries, there is still a lack of adequate water quality, which also leads to numerous waterborne diseases [
6,
7,
8]. It is estimated that over 3 billion people do not have access to safely managed sanitation facilities [
9]. Moreover, the lack of appropriate education regarding the proper management of water resources causes an increase in the amount of pollutants in water in urban spaces [
10]. This problem mainly affects underdeveloped countries, where only a small percentage of wastewater is treated in centralized municipal sewage treatment plants, and the rest is discharged into water sources without any treatment, thus leading to overall resource pollution [
11].
Water is crucial not only for the proper functioning of society but also for the global economy. Statistics show that only 3% of water is in its natural state [
12,
13,
14]. In this context, it is extremely important to obtain data and analyze them effectively in order to protect the water [
15,
16].
Surface water resources are crucial for socio-economic development and the protection of ecological systems and water supply for people. However, in countries with depleted surface water resources, most drinking water comes from groundwater resources [
17].
The element connecting the ecosystem of surface and groundwater is springs. Water from these springs is very often used for drinking purposes in karst areas but also in areas used for recreation [
18,
19]. The water component of springs is influenced by both natural and anthropogenic factors. The first group includes geological conditions, climatic conditions and land development, as well as land use [
20]. Due to the fact that water in springs appears on the surface through a network of faults, cracks or contact with rocks [
21], it is particularly threatened by migrating leachates [
22,
23]. The topography of the area also influences the amount of pollution [
24]. The spatial development of the immediate vicinity of the springs, including the presence of, e.g., landfills and sewage treatment plants, definitely increases the risk of contamination [
25,
26]. The migration of leachates is also stimulated by the amount of precipitation. In addition to the physicochemical parameters of spring waters, an important issue when determining their suitability for consumption is the content of microorganisms [
18]. Water intended for drinking should not contain pathogens [
27], but spring water often contains bacteria, fungi and viruses that cause various disease epidemics [
28].
Drinking water is water that is of acceptable quality (according to the WHO’s guidelines or national standards for drinking water quality) in terms of physical, chemical and microbiological properties, which can therefore be used safely [
29]. Due to the fact that maintaining the appropriate quality of drinking water is necessary for ensuring human health, it is essential to supervise this quality by monitoring this water through constant control using sensors. The latter are a guarantee of constant control and are included in the functioning of the ‘smart city’ [
30]. Smart cities are an innovative concept in managing urban environments and are intended to guarantee sustainable development and improve the quality of life by combining technical, institutional and economic concepts together with modern information and communication methods. This concept is based on the use of systems that monitor environmental parameters (e.g., sensors). And this solution can be used in every place, not only in cities. One of the elements of this system is what is termed ‘smart water’, which is based on the use of economical sensors that can provide data through the use of cellular networks, for example. Such infrastructure is key for ensuring that the population drinks water of sufficient quantity and quality under a wide range of changing operating conditions. Thanks to the large amount of data obtained from sensors, it is easier to assess the water quality in a given area, which also allows for risk assessment of these waters. Such actions will enable the implementation of the goals of the smart water concept and the rational management of water resources. Based on the data, it is possible to conduct a water risk analysis by, e.g., using indicator methods like the Water Quality Index (WQI) [
31,
32,
33,
34].
Springs in urban spaces should be subject to water quality monitoring in order to determine changes in their physicochemical and microbiological parameters and to identify factors that may cause these changes. This is important for maintaining appropriate water quality, limiting the development of diseases caused by the consumption of water of reduced quality and implementing a sustainable water management strategy in municipalities.
One example of a location where water from a spring is drawn by residents of nearby cities and tourists is the Zimny Sztok spring in Stanica (southern Poland). Due to it being located near a road and in constant use, the spring is also at risk of pollutant migration. This research included two measurement series in 2023 and 2024 of selected physicochemical and bacteriological parameters. The aim of this paper is to examine the quality of water in the spring, determine potential risks by using the WQI and present the general problem of people consuming water from urban sources without knowing about their parameters. These are the preliminary results of this research that will be developed and are intended to illustrate the problem of the lack of monitoring of water in springs.
2. Study Area
This paper concerns a Quaternary spring located in the town of Stanica (Pilchowice commune), in the southern part of Poland (
Figure 1). In terms of physicogeography, this area is part of the Silesian Upland macroregion and the Rybnik Plateau mesoregion [
35]. The spring is located at an altitude of 224.6 m above sea level. The research area is located in the transitional continental–marine climate zone. The average annual temperature here is 8 °C; the average annual rainfall is about 700–800 mm. The area is dominated by southwestern and north-western winds with average speeds of 2.5 m/s, which carry dust and gas pollution to the surrounding cities. Hydrographically, the area is located in the Oder basin, in the Upper Oder water region, in the Ruda catchment area [
36].
The spring is located in a forest area. The distance from the source to the nearest village is 1.25 km to the east. The village of Stanica, which belongs to the Pilchowice commune, is characterized primarily by single-family buildings. About 30% of the commune is connected to the sewage system. The spring is also located 500 m west of individual single-family houses (Biały Dwór) that belong to the Rudy commune. Work is currently underway to connect these houses to the sewage network. The project of connecting houses to the sewage system for the entire Rudy commune is expected to last until 2027. The distance from the spring to the road is 7 m. There are agricultural fields approximately 400 m to the east and 700 m to the north.
The oldest geological formations in this area form a structural unit known as the Upper Silesian block. These are Precambrian crystalline rocks, mainly mica schists and paragneisses, on which there are Cambrian (siltstone and diabase), Devonian (sandstone and then limestone and dolomite with numerous inserts of claystone, mudstone and marls), Lower Carboniferous rocks (mainly sandstone, mudstone, shale, conglomerate) and carbonaceous sediment of Upper Carboniferous productive deposits. The Upper Carboniferous sediments belong to the older paralic series, which are composed of fragmentary rocks with interlayers of marine sediments, and developed in the form of gray mudstone, sandy mudstone and claystone interbedded with fine-grained sandstone and coal seams. Between the sediments of the paralic and mudstone series, there is the local belt of the Upper Silesian sandstone series in the form of medium- and fine-grained sandstone and, less often, coarse-grained sandstone and conglomerates with interbedded mudstone, among which there are thicker coal seams. The sediments of the Carpathian Foredeep include Miocene clay and sand with siderites, as well as sandy and marly clay, sand, clay shale with gypsum and anhydrite. These formations are covered by Quaternary deposits, represented mainly by sand, gravel, clay, glacial boulders and boulder clay (
Figure 2).
According to the hydrogeological map, the spring is located in an area with a very low risk to water quality. There are two aquifers in the research area in question—the Quaternary and the Neogene. The Quaternary is associated with layers of sand and gravel of the river or glacial formations, as well as intra-moraine sands of various extents and thicknesses. The upper level is located in the upper part of the Quaternary sediments; it often has the character of suspended water at various depths and is underlain by semi-permeable Quaternary clay or impermeable Neogene clay. The second level is found at a depth of approximately 7–10 m and is located on impermeable glacial, Quaternary clay or directly on Miocene clay. Isolating layers, unlike aquifers, are more often spatially continuous. The Quaternary water supply is supplied directly from atmospheric precipitation, and the basis of drainage here is surface streams. The usable Neogene aquifer is associated with sand and sand–gravel inserts, 7–22 m thick, located in the Sarmatian clay complex. Water utility resources in the Neogene zone have been identified to a depth of approximately 90–100 m, and these are sub-artesian waters. The aquifers are recharged directly from the ground surface outcrops of permeable Sarmatian formations and through permeable Quaternary formations. The flow of water in these aquifers is towards the west [
37] (
Figure 3).
Quaternary waters are characterized by high values of total mineralization, reaching up to 1200 mg/L. They belong to the sulfate–bicarbonate–magnesium–calcium type. Due to the increased concentrations of sulfates, iron, manganese and nitrates, they are classified as water quality class III.
The waters found in the Tertiary sand and gravel complex are fresh waters with mineralization up to 700 mg/L. These waters are of the bicarbonate–calcium and bicarbonate–calcium–magnesium types. Due to exceeding the permissible values of iron and manganese, they are classified as quality class III.
3. Methodology
Research in the Zimny Sztok spring included two measurement series conducted in November 2023 (autumn) and February 2024 (winter). During field research, water samples were collected for physicochemical and bacteriological analysis, which was performed in an accredited laboratory. In terms of physicochemical parameters, the values of electrical conductivity, pH, Ca, Na, K, Mg, Fe, Al, Mn, Ni, Cu, Sr, S, Cl, SO4, HCO3, NO3, NO2, NH4, PO4, N, TOC, Pb, Cd, Cr, Hg, Zn, acidity and alkalinity were obtained. The potential presence of pathogens in environmental waters was inferred based on the determination of coliforms, enterococci, P. aeruginosa and C. perfringens. The results were compared to values from the Regulation of the Minister of Health in 7 December 2017 on the quality of water intended for human consumption, which are publicly available on the Internet in the Journal of Laws 2017, item 2294.
The Water Quality Index was calculated for both series in order to determine the risk to water quality. The WQI was calculated in relation to values stated in the Guidelines for drinking-water quality (GDWQ) proposed by the WHO. This index was used as the one of the most representative indexes for water risk assessment [
38]. Calculating this index includes the following stages: (i) assigning weights to physicochemical parameters, (ii) developing a rating scale and (iii) calculating the WQI.
The WQI was calculated for the six parameters and assigned appropriate relative weights on the basis of the literature [
38], dissolved oxygen (0.22), total number of microorganisms at 22 ± 2 °C (0.21), pH (0.15), total phosphate (0.13), nitrates (0.13) and EC (0.16).
Following this, the quality rating scale (q
i) was calculated using Equation (1).
where
Ci is the concentration of parameters;
Si is the standard value of parameters.
The WQI is calculated using the following equation:
where
SI is the subindex calculated from Equation (3).
The index classifies water into the following classes: WQI < 50, excellent water; 50–100 WQI, good water; and WQI > 100, poor water.
4. Results and Discussion
The division into the supply of another hydrographic facility is surface discharge. A gushet is a spring sphere of discharge. The spring yield was measured in both measurement series. The yield of spring was equal to 94 L/h in November 2023 and 99 L/h in February 2024.
Taking into account the content of main ions, the chemical type of water from both measurement series was determined. In the first series of measurements, the water from this spring is classified as bicarbonate–calcium, and in the second series, it is classified as bicarbonate–calcium–magnesium water.
The resulting biological and physicochemical values were compared to the national quality standards of water intended for human consumption (Regulation of the Minister of Health of 7 December 2017 on the quality of water intended for human consumption), limits for the first class of water quality (Regulation of the Minister of Maritime Economy and Inland Navigation of 11 October 2019 on the criteria and method of assessing the status of groundwater bodies) and to the Guidelines for drinking-water quality (GDWQ) proposed by the WHO.
Overall, taking into account the results of both chemical analyses and relating them to the national standards for drinking water, it was revealed that the standards were not met for pH, dissolved oxygen, total number of microorganisms at 22 ± 2 °C and total number of microorganisms at 36 ± 2 °C. When we compare the results to the first-quality class, the standards are not met for pH, nitrates and sulfates. Additionally, copper is at the limit. When comparing test values with the WHO’s standards, the situation is identical to national standards for drinking water, except for the dissolved oxygen value.
The value of specific electrolytic conductivity was 208 µS/cm in the first measurement series and 217 µS/cm in the second series. Electrical conductivity (EC) is a parameter used to indirectly assess water mineralization, which, in shallow waters exposed to anthropogenic pollution, may exceed the value of 1000 µS/cm [
39]. These waters were characterized by a reduced pH value, which is typical for this area. Unfortunately, excessive consumption of acidified water may cause health consequences such as gout, hypertension, inflammation of the digestive system’s organs and skin diseases. However, a lower pH can inhibit the growth of bacteria such as E. coli, due to the presence of chlorine [
40]. Regarding this parameter, the pH did not reach the appropriate value, but water quality tests carried out for this spring will continue in the spring and summer. The DO values in the first and second measurement series were lower than the standards. In the first series, in which <300 in the total number of microorganisms was at 22 ± 2 °C, the DO value was lower, suggesting that the bacteria consumed surrounding oxygen [
41].
Water pollution with nitrates is primarily caused by their use in agricultural fertilizers to increase crop yields. Nitrogen fertilizers are the main source of water-soluble nitrates and nitrite compounds in the soil [
42]. Additionally, increased nitrate content in water may be the result of contamination by human, animal and industrial waste [
43]. It should be noted that water in wells, shallow groundwater and water in springs are subject to increased nitrate contamination [
44]. Despite the fact that the nitrate content in the Zimny Sztok spring did not exceed the permissible limit for drinking water, the content classifying these waters as the first quality class was exceeded. Due to the fact that the spring is located next to the road, the amount of nitrates should also be controlled. An increased supply of nitrates can be carcinogenic [
45]. The content of nitrates in the water should also be controlled due to the proximity of single-family houses that are not fully connected to the sewage system and because nitrates may migrate to the water from leaking septic tanks.
As mentioned before, taking into account the permissible water quality limits for the first class (
Table 1 and
Table 2), copper is exactly on the border between the first and second classes. There is no value for copper in the national standards for drinking water, and the WHO defines the standard as 2 mg/L. Despite this fact, it should be taken into account that this indicator would reduce the quality of water from this source. Excessive concentration of this ion may also cause heavy metal toxicity, which may result in hypertension, kidney failure, liver failure and brain dysfunction [
46].
Current national legal acts require that drinking water be analyzed in terms of the total number of microorganisms present in it. The total number of microorganisms growing at 36 ± 2 °C may suggest the presence of pathogenic bacteria (those growing at human body temperature, mesophilic bacteria), while the total number of microorganisms growing at 22 ± 2 °C (psychrophilic bacteria), similarly to the number of coliform bacteria, is used to assess the condition of the water supply network and the operation of treatment systems [
47]. Legal solutions refrain from specifying a categorical value of this parameter, requiring its monitoring in order to detect results that deviate from the normal state, which is estimated based on repeated tests. Therefore, it is important and appropriate to conduct further microbiological research in the waters of this spring. It should be added that, during laboratory analysis, the presence of the sought indicator microorganisms in a water sample depends on many factors. These include, among others, the condition of the water supply network, collection technique, storage conditions, analytical method and the human factor. Periodic detection of the presence of indicator bacteria in drinking water may be related to the contamination of water intake with feces and insufficient treatment and disinfection, as well as other reasons—for example, the multiplication of microorganisms inside the water supply network in the form of the so-called biofilm. In the event of increased water flow, the biofilm may detach from the spring outlet and penetrate into the analyzed sample. In the second measurement series (lower temperatures of water and air), no bacteria were observed in the water. It should also be noted that total number of microorganisms at 36 ± 2 °C were also observed in the first sample. Their content was over three times higher than the permissible standards. Because this test suggests that the water contains bacteria that prefer to grow at body temperature, drinking such water may be dangerous; however, it must be confirmed that this level of bacteria in this water persists.
In addition to comparing the obtained analytical results to all mentioned standards, WQI values were calculated for both series. When calculating the WQI, data on dissolved oxygen, the total number of microorganisms at a temperature of 22 ± 2 °C, pH, total phosphates, nitrates and EC were used. The calculated values of the WQI show that one parameter can significantly influence its total value (
Figure 4 and
Figure 5). In the first series of measurements, in which it was found that the total number of microorganisms at a temperature of 22 ± 2 °C was greater than 300 CFU/mL, with the acceptable standard being 100, the total WQI value was over 60% higher than if this parameter had not been taken into account. The total value of the indicator in the first measurement series was 99.67. The WQI result (close to 100) obtained for the Zimny Sztok source from the first measurement series can be compared with WQI values from the area of typical waste landfills [
48]. In the case of drinking water sources, the values of this indicator should be in the range of 0–25 [
49,
50].
Such a high WQI value indicates a high level of water pollution. The calculated WQI value for the second series of measurements indicates that the water in the spring is of excellent quality (WQI is less than 50;
Figure 5). Such a large change in the index value is caused by the lack of presence of microorganisms. In the second series of measurements, the influence of EC and pH is more visible. It can be concluded that for water risk assessment, the result from the second series is more reliable. Analyzing the calculated WQI values for both measurement series, it should be noted that the content of dissolved oxygen and the pH value have a large share in the final value of the indicator.
The results of the WQI calculations indicate that better water quality was recorded in the second measurement series. Meanwhile, the very high value of the indicator in the first measurement series results, as already mentioned, from the large total number of microorganisms at a temperature of 22 ± 2 °C. If the WQI value was calculated by changing this parameter to another physicochemical parameter, it would turn out that the quality of this water is better, compared to the second measurement series. Having the obtained results of physicochemical and bacteriological analyzes at our disposal, the data for this bacteriological parameter should be omitted in the calculation of the WQI. It should be noted that the occurrence of bacteria in the waters of springs such as Zimny Sztok is often dependent on the episodic inflow of pollutants from leaky septic tanks, animal activity or other anthropogenic activities. The first step before further water measurements in this source and in the use of water by residents should be to protect this source against the inflow of pollutants from the surface. Based on the analysis of the spatial development map of the immediate area, it can be concluded that the main sources of pollution may be fertilizers from agricultural fields, leaky septic tanks and pollutants migrating from the nearby road.
Analyzing time changes for individual parameters, the largest increases were observed in the case of mercury, zinc, cadmium, iron, bicarbonates and sodium. In the case of mercury between November and February, the content increased 30 times. Despite the fact that mercury concentrations in the tested source are very low, such an increase should be taken into account in any subsequent measurement because heavy metals naturally occurring in the aquatic environment in higher concentrations may be toxic when they accumulate in organisms [
51]. Changes in water pH are related to the metal content. Even though the pH value in water was lower in the first measurement series, no higher concentrations of zinc or copper were observed in this series. As the Zimny Sztok spring is located in an urban space, higher concentrations of metals in water in the second measurement series can be correlated with increased heating of apartments and the use of various heating sources, from which pollutants may migrate to the atmosphere and from there to water. In terms of hardness, the water in the spring is classified as soft. This condition persists even after the alkalinity value increased by 70% in the second measurement series. A decrease in pollutants in the second measurement series was noticeable only in the case of chromium (a decrease of approximately 83%), nitrates (a decrease of approximately 18%), phosphates (a decrease of approximately 13%) and potassium (a decrease of approximately 9%).
In terms of factors such as season, sampling methods, geology conditions and anthropogenic activities, it should be noted that only the air temperature and anthropogenic activities related to heating apartments, limiting the amount of fertilizers used, and changing the number of inhabitants using the source could have an influence on the value of the WQI. The method of collecting samples for analysis was identical in both cases, and the analysis was performed in the same accredited laboratory.
It is worth remembering that, in the world, about 65% of groundwater is used for drinking and irrigation, 20% of this water is used for feeding animals and about 15% of groundwater is used for industry purposes [
13]. Poland is one of the countries that primarily uses groundwater resources for drinking purposes. Springs are a valuable complement to these resources; therefore, it is necessary to use them rationally. The described spring has existed since the 19th century. Due to the fact that the Zimny Sztok spring is located by the road and is protected by a concrete casing, it is necessary to take a number of actions to ensure that these waters are sustainably used. It should be mentioned that there is no continuous monitoring of water quality at this source. However, this point is not included in the observation network of the State Environmental Monitoring program, which would certainly be a guarantee of obtaining more quality data. Unfortunately, monitoring studies in springs are rarely performed, which is due to the fact that piezometers and wells dominate the system. In order to use resources sustainably, it would also be necessary to secure the area around the source and the intake point itself, control leaks in septic tanks in the commune, limit the possibility of the migration of pollutants from fertilizers and also undertake educational activities for local residents and other users in order to present the current chemical and bacteriological composition of these waters, determining the consequences of consuming water that does not meet the appropriate standards for drinking water and counteracting anthropogenic threats.
5. Conclusions
The aim of this study was achieved by conducting tests in spring waters, presenting the results of these tests, calculating the WQI and indicating what further course of action should be taken in the field of monitoring these waters.
Based on the tests of physicochemical parameters, it can be concluded that the conductivity and most of the parameters in water samples from the Zimny Sztok spring are within the safe limits according to the WHO’s guidelines and are also at a safe drinking level based on national standards. The only exceedances concern nitrates and copper ions. The pH of the water is lowered by approximately 1 point compared to the lower limit of standards, which is typical for the entire region.
The obtained results indicate a certain difference in concentrations in both measurement series, e.g., a 30-fold increase in the mercury concentration in the second measurement series or an 8-fold increase in cadmium concentration. In terms of microbiological parameters, in the first measurement series, >300 cfu/mL was recorded for the total number of microorganisms at a temperature of 22 ± 2 °C and 68 cfu/mL for the total number of microorganisms at a temperature of 36 ± 2 °C. Due to the fact that during laboratory analysis, the presence of the sought indicator microorganisms in a water sample depends on many factors, research on these two parameters should be continued to confirm the origin of these values.
WQI values were different in both measurement series. In the first series of measurements, the WQI was over 99, and in the second series, it was approximately 41. Importantly, such a high value of the indicator in the first series is the result of the high value of the total number of microorganisms at a temperature of 22 ± 2 °C. Even though the WQI is one of the most optimal indicators for assessing water quality and risk, in the analyzed case, its value might have caused an incorrect analysis of water quality changes in November and February. Further periodic or permanent tests of water quality in terms of physicochemical and bacteriological parameters, including spring parameters, should be conducted by the commune’s authorities to ensure the reliability and representativeness of the test results. Additionally, thanks to measurements performed in different seasons of the year, it will be possible to determine the seasonality of changes. Conducting geochemical modeling to determine speciation and saturation rates will also be a valuable element of further research.
The relationship between the urban space and water determines the healthy prosperity and sustainable development of such areas. In this context, it is important to conduct rational management of water resources but also formulate development strategies based on the state of the water resources in question. In order to maintain appropriate quantitative and qualitative resources of water intended for consumption in urban spaces, it is necessary to monitor and control parameters, as well as analyze the possible effects of consuming such water. Such actions should also be taken in the case of the Zimny Sztok spring. This is important not only in the case of water that is introduced into the system but also, above all, in the case of water that is collected by local residents from springs.