A water demand end-use model was developed to predict water demand patterns with a small time scale (1 s) and small spatial scale (residence level). The end-use model is based on statistical inform...

Simulating Residential Water Demand with a Stochastic End-Use Model

The effects of changing water flow velocity on the formation of biofilms and water quality in pilot distribution system consisting of copper or polyethylene pipes.

Assessing the public health risk of microbial intrusion events in distribution systems: Conceptual model, available data, and challenges

The Netherlands is one of the few countries where chlorine is not used at all, neither for primary disinfection nor to maintain a residual disinfectant in the distribution network. The Dutch approach that allows production and distribution of drinking water without the use of chlorine while not compromising microbial safety at the tap, can be summarized as follows: 1. Use the best source available, in order of preference: microbiologically safe groundwater, surface water with soil passage such as artificial recharge or bank filtration, direct treatment of surface water in a multiple barrier treatment; 2. Use a preferred physical process treatment such as sedimentation, filtration and UV-disinfection. If absolutely necessary, also oxidation by means of ozone or peroxide can be used, but chlorine is avoided; 3. Prevent ingress of contamination during distribution; 4. Prevent microbial growth in the distribution system by production and distribution of biologically stable (biostable) water and the use of biostable materials; 5. Monitor for timely detection of any failure of the system to prevent significant health consequences. OA-fund TU Delft

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The Dutch secret: how to provide safe drinking water without chlorine in the Netherlands

Residential water use constitutes a major part of urban water demand, and has be gaining importance in the urban water supply. Considering the complexity of residential water use system, an agent-based social simulation, i.e. the Residential Water Use Model (RWUM), is developed in this paper to capture the behavioral characteristics of residential water usage. By disaggregating total water demands down to constituent end-uses, this model can evaluate heterogeneous consumer responses on water, taking into account the factors of market penetration of water-saving technologies, regulatory policies, economic development, as well as social consciousness and preferences. Also, uncertainty analysis technique is innovatively applied in this agent-based model for parameter calibration and model robust testing. According to the case study in Beijing, this model can provide insights to water management agency in evaluating different water usage polices, as well as estimations for potential water saving for future infrastructure development planning.

Agent-Based Residential Water Use Behavior Simulation and Policy Implications: A Case-Study in Beijing City

Today, there is a growing interest in network water quality modelling. The water quality issues of interest relate to both dissolved and particulate substances. For dissolved substances the main interest is in residual chlorine and (microbiological) contaminant propagation; for particulate substances it is in sediment leading to discolouration. There is a strong influence of flows and velocities on transport, mixing, production and decay of these substances in the network. This imposes a different approach to demand modelling which is reviewed in this article. For the large diameter lines that comprise the transport portion of a typical municipal pipe system, a skeletonised network model with a top-down approach of demand pattern allocation, a hydraulic time step of 1 h, and a pure advection-reaction water quality model will usually suffice. For the smaller diameter lines that comprise the distribution portion of a municipal pipe system, an all-pipes network model with a bottom-up approach of demand pattern allocation, a hydraulic time step of 1 min or less, and a water quality model that considers dispersion and transients may be needed. Demand models that provide stochastic residential demands per individual home and on a one-second time scale are available. A stochastic demands based network water quality model needs to be developed and validated with field measurements. Such a model will be probabilistic in nature and will offer a new perspective for assessing water quality in the drinking water distribution system.

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Importance of demand modelling in network water quality models: a review

There is growing interest in modeling water demands on short time scales (as brief as one second) and small spatial scales (typically single homes). Buchberger et al. (1996, 2003) have developed the Poisson Rectangular Pulse (PRP) model for this purpose. Blokker et al. (in prep.) have developed an end-use model SIMDEUM (which stands for SIMulation of Demand, and End-Use Model) which is based on statistical information from end-uses and does not require any flow measurements. SIMDEUM was developed and validated for Dutch water use. In this paper the PRP model and SIMDEUM are compared with each other and with measured indoor water demands from 21 homes in Milford, Ohio. Both models compare well to the measurements; the PRP model works better in simulating the cumulative flows of a sum of 20, SIMDEUM works better in simulating the flows of a single home.

Comparison of water demand models: prp and simdeum applied to milford, ohio, data

Measuring discoloration risk: resuspension potential method

The paper under discussion is one of the few published works related to the stochastic modeling of nonresidential water demand. The model proposed by the authors is of great interest and will help in improving the knowledge of consumption patterns associated with different types of uses. It will also serve as an excellent starting point for future developments in water-demand modeling. The discussers acknowledge that developing such a model is extremely complex due to the large heterogeneity of facilities and equipment and, in general, the diversity in users’ consumption patterns. Therefore, the discussers want to extend their most sincere congratulations to the authors for their study. However, based on the discussers’ experience, it is appropriate to make some clarifications regarding the modeling of water demand in hotels that will contribute to improving future developments in this field. For this purpose, actual consumption data obtained in different measurement campaigns for various hotel rooms is presented. In total, approximately 1,500 full days of measurements were analyzed. Water consumption was recorded with a volume resolution as low as 0.1 L, which allowed for a meticulous data analysis. By means of a specific software tool, the discussers were able to discriminate among the different uses of water in hotel rooms and to classify them into various microcomponents (toilet cistern, shower, and tap). This analysis was possible thanks to the high resolution measurements taken for hot and cold water consumption (Cobacho et al. 2005). As a result, the individual characteristics of the various end-uses present in a hotel room were obtained. The conclusions of this study are used to assess some of the assumptions made by the authors in their work.

J. C. van Dijk

Papers

Importance of demand modelling in network water quality models: a review

Comparison of water demand models: prp and simdeum applied to milford, ohio, data

Measuring discoloration risk: resuspension potential method

Discussion of "Simulating Nonresidential Water Demand with a Stochastic