The article deals with the influence of heat transfer between hot and cold water pipes on the growth of Legionella bacteria, which is a significant problem in hot water preparation and distribution systems. Legionella bacteria need a very specific environment for their formation, where systems for the preparation and distribution of hot water are the ideal place for its growth. The conditions for the growth of Legionella were investigated by numerical simulations of heat conduction in the calculation program CalA 4.0 Several variants differing in geometrical arrangement of the pipes and the thickness of the thermal insulation of the pipe were simulated. The results of the simulations confirm the need to insulate the water pipes in order to prevent the growth of Legionella.

The current trend and sustainable approach to reducing or eliminating carbon dioxide emissions lie in the use of renewable energy. According to ČSN EN 16147: 2011, the use of shower and bathtub accounts for approx. 48–75% of the total hot water demand, depending on the size and facilities of the household. [1] Some owners and operators are looking for new ways of recycling wastewater, which can be supplemented by obtaining thermal energy for preheating hot water or as a source of thermal energy for heat pumps in the case of hot greywater collection. This paper deals with a summary of laboratory procedures for testing technological units within the project “Collection and reuse of heat energy from wastewater, combined with the use of treated wastewater”.

This article focuses on the issue of measuring the temperature of water in water distribution networks. Under certain conditions, the increased water temperature can have a negative effect on the quality of drinking water, which in extreme cases can lead to the loss of the status of hygienic safety of drinking water. The article contains an overview of the negative consequences of increased water temperature on its quality, a clear presentation of all parts of the distribution system in which the water temperature can change and describes the existing procedures for measuring the water temperature. Part of the work is also a description of the proposed methodology for continuous measurement of water temperature in the distribution network, the feasibility of which was experimentally tested in laboratory conditions.

The aim of this research is a comprehensive evaluation of the retention capacity of the landscape depending on the use of soil protection technology in a selected locality and a comparison of selected hydropedological characteristics in the context of land management. The area is modeled in terms of erosion and runoff conditions. In the next stage, the plan is to evaluate the changes in selected physical hydropedological characteristics during the year in the conditions of climate change.

This work deals with research and development of a new grouting mortar with increased chemical resistance based on portland cement. The aim of this work is to verify new mixtures with specific admixtures. Resistance to attack by external sulphates was monitored, while the test specimens were placed in a sulphate solution of 29.8 g / l (44 g / l Na₂SO₄) according to DIN 19753. The results of the work show that the addition of the optimal amount of crystalline waterproofing admixture can achieve a significant increase in resistance to sulfate corrosion. Based on the obtained results, new mixtures will be proposed, optimized by the addition of suitable secondary raw materials.

Denitrifying bioreactors are used to remove nitrates from surface runoff in agricultural areas and thus to prevent them from entering surface water bodies. The course and rate of the denitrifying process is influenced by many factors. One of the most important ones is the inflow water quality, as the water can be contaminated also by pollutants such as pesticides.
We have paper proposed and optimized a methodology for the long-term testing of the effect of pesticides on the denitrification process. This batch test was performed to evaluate the inhibition of the denitrification rate. Apart from optimizing the nitrate dosage method, we determined as well their optimal dose (15 mg/l) and also the most suitable NaHCO₃ concentration in the deionized water (0.5 mg/l).

The paper deals with the requirements of the quality of potable cold water in water piping system inside buildings. The contribution focuses on temperatures, which should be provided in the water piping system and describes the main risks and factors influencing the temperature of cold water. The paper shows the basic measures and possible solutions of the problem of ensuring the sufficient potable water exchange in buildings. In buildings, there usually are not ideal conditions for ensuring the hygiene of potable water, the resulting hygienic risks can be reduced using the right technical solution.

Internal erosion is one of the most common causes of failure of hydraulic structures. A special case is a backward erosion piping during which an exceeding of critical hydraulic gradient occurs on the edge of the structure foundation interface. This becomes especially dangerous for the structure when the foundation consists of sand or very sandy soil that is very easy to erode. The sand property of erodibility is not yet fully described. In this paper, an experimental device used for the rate of erosion determination for a picked sand is presented as well as a calculation of the erosion coefficient which is usually used to describe soil erodibility. Furthermore, the paper contains critical hydraulic gradients during which the erosion occurred.

The second part deals with the properties of plastic pipes and their service life, describes CVPC pipes, PR-R pipes, ESC mechanism, chemical degradation, mechanical degradation, hinge spacing, inspections of old installations, certification of pipes, pouring into concrete, corrosion prevention measures, lowest criterion prices and conditions VdS CEA 4001.

The article focuses on the service life of pipes and sprinklers of sprinkler fixed fire extinguishing systems. Both components have a common enemy, which is corrosion. It appears in various forms and for various reasons.

The article describes the change of water outflow depending on the shape of the siphonic drain. For several selected shapes of siphonic drains, the hydraulic capacity was measured depending on the height of the water on the board, which simulates the roof and is located in the storage tank. An outflow curve was plotted for each inlet, from which the maximum hydraulic capacity is evident, which is based on the boundary conditions of the laboratory measuring device. For comparison purposes, photographs of water flow in the pipeline and above the level of the simulated roof were recorded. Recording was performed for all measured drains and also for each height of water.

The subject of the complex repair of the ceiling structure of the water reservoir Pasohlávky was the remediation and static provision of the unsatisfactory reinforced concrete structure. The original condition was inadequate, parts of the concrete structure were dropped due to steel due to steel corrosion and small cover layers of concrete.

Example of rehabilitation of sewerage facilities, shafts and chambers in an environment of the historic city center with increased loads of chemical-biogenic corrosion. Possible causes and consequences for both, original and newly constructed, building structures. Modification of the proposed solution, including the design of an appropriate construction structure and installation technology solution.

The design of a solar system for the preparation of hot water in an apartment building is analyzed by computer simulation. The analysis shows the effects of the design of the area of solar collectors, climatic conditions, the connection of the circulation circuit and the design of the volume of the solar storage tank on the solar coverage and specific heat gains.

Many structural concrete elements of dams must withstand extreme frost stress and abrasion of fast-flowing water. At present, several reconstructions of concrete overflows, chutes of dams or weirs are underway or have already taken place with the requirement for increased resistance to abrasion. From the point of view of ČSN EN 206, abrasion-resistant concretes are determined by exposure class XM, but the evaluation criteria and testing methods are insufficient. The article deals with a closer presentation of the requirements for the properties and development of concrete with high resistance to abrasion and frost and its subsequent testing.

The cause of the odor after the generational replacement of the gas boiler can be reduced air exchange in the room, improperly designed waste pipes, or even insufficient hygiene. The level of cleaning and hygiene is solved by the apartment user. Sufficient ventilation and treatment of the waste pipe, such as the installation of an aeration valve, should be designed by a person skilled in the art.

In the Czech Republic, the constructed wetlands (CWs) have been used as wastewater treatment technologies since 1989. They are usually designed for small communities to 500 PE exceptionally to 2 000 PE. At present, about 300 CWs are in operation in the Czech Republic. Majority of them are designed with horizontal subsurface flow, while vertical subsurface flow (VF) constructed wetlands are still rarely used. Compared to abroad, vertical filters (beds) in the Czech Republic are only a new technology. Proof of this are the results from the largest vertical filter operated at CW Dražovice for 850 PE. The technology of vertical filter has great potential to improve the reputation of constructed treatment wetlands in the Czech Republic.