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Over the years, researchers have been conducting studies to investigate the water consumption profile in buildings; these studies have contributed to the accumulation of knowledge regarding the correct sizing of hydraulic systems in buildings. In the context of the methods for the characterization of system demand or loading values, the procedures commonly employed to obtain the project flow rate were primarily proposed in the mid-20th century. These models require revision and adaptation to the current water consumption values. In recent years, certain researchers have proposed simulation models with an application focus on water distribution systems owing to the random and temporal behavior of water demand in this system type. In this study, a water-demand stochastic simulation model in residential buildings is proposed, which encompasses the behavioral modelling of users and their interaction with the system to improve the design process of water distribution systems. Therefore, geographical and population factors (quantity, distribution, and organization) were considered for the behavioral modelling of users; regarding the system modelling, aspects related to the hydraulic system were considered, such as the relation between system components, the type of sanitary appliance, and the number of available devices. Different simulations—with several different types of showers—were conducted using the proposed model. Comparing the flows obtained from the simulation and from the Brazilian standard, for all system components, the decrease in the project flow rate varied from 4% to 61%. In terms of material consumption regarding the pipe (PVC), the decrease varied from 25% to 63%. Practical application: When assessing potential designs for components in water distribution systems in buildings robust information is required for water demand across different time scales. The use of simulation models represents an important advance for the dimensioning process of these components, since it is possible to know a wider range of information about the system demand possibilities. The use of this type of model, as discussed in this article, will equip the designer with an enhanced decision making capacity.

ResumoEste artigo tem como objetivo avaliar os resultados obtidos na estimativa das vazões de projeto para o dimensionamento de hidrômetros de sistemas prediais de água fria com medição individualizada, empregando um método probabilístico aberto e o método empírico recomendado na normalização brasileira.Como os resultados finais indicam grandes diferenças nas vazões de projeto estimadas pelos dois métodos, é importante realizar pesquisa de campo a fim de verificar os valores obtidos. O modelo probabilístico aberto permite que o projetista ajuste as variáveis relacionadas ao uso da água para refletir melhor a realidade das vazões no sistema predial em função de diferentes condições de utilização. Por isso, seu emprego apresenta-se mais vantajoso, principalmente em sistemas com medição individualizada, em que a especificação do hidrômetro é efetuada, entre outros parâmetros, em função da vazão de projeto.Palavras-chave: sistemas prediais, medição individualizada de água, eficiência de uso da água, gestão do uso da água. AbstractThe objective of this paper is to compare the results obtained in the estimate of the design flow rates to the dimension water meters of water submetering systems in buildings by means not only from an open probabilistic model but also from the empirical method recommended by the Brazilian Standard. As the final results show considerable differences in the design flow rates estimated by both methods, it is extremely important to perform field survey in order to check the obtained values. The open probabilistic model enables the practitioner to adjust the variables related to the water use to better reflect the flow rates in the plumbing system according to the different conditions of use. Due to this advantage, its use appears to be more beneficial than the empirical method, mainly concerning submetering systems where the specification of the water meters takes into account the design flow rate.Keywords: plumbing systems, water submetering, efficient water use, water management.Endereço para correspondência: Marina S. Denomina-se medição individualizada a setorização do consumo de água com a instalação de pelo menos um hidrômetro em cada

This study aims to evaluate impacts of reducing toilet flush volume from 6.8 to 4.8 Lpf with laboratory and field studies. In laboratory, 260 tests were performed including water consumption, waste removal and solid transport tests, in 20 different toilets produced by national and international manufacturers. These tests demonstrated that a simple reduction in flush tank water level was not a viable solution for reducing flush volume, due to flush energy loss. Toilets are designed to work with certain water volume, and reducing this volume without studying the consequences that this could cause, can make with the toilet fail. Toilets approved according the standards ABNT NBR15097, ABNT NBR15491 and ASMEA112.19.2 were installed in 10 houses. The monitoring of water consumption and sewage system videos were conducted during eight months. When 6.8-Lpf toilets were installed, the average toilet water consumption was 16.6L/inhabitant/day. For 4.8-Lpf toilets, this value increased to 17.6. The number of flushes/person/day increased after toilets replacement, indicating that users applied successive flushes. Videos showed blockages in sewage system horizontal pipes. Findings from this study suggest that low-flush toilets do not decrease total water use, and may result in increased water use. In addition, they can cause clogging and solid deposit on sewage system. Practical application: Many management failures have affected the world water availability. Water demand has increased with population growth, and unless the equilibrium between water demand and supply is restored, the world will face increasing water shortage. However, it is essential to study the way of reducing water consumption. Without an effective analysis, instead of bringing benefits to population, water consumption reduction can lead to clogging and negative consequences on sewage system performance, causing disorder to them. It is recommended that manufacturers did not reduce the toilet water consumption without a study on the impact caused on the sewage systems, as well as designers should be careful when specifying sanitary appliances.