This paper presents a comprehensive method for assessing the technical condition of water treatment plants as part of a set of procedures for assessing the entire water supply system. The proposed method of water treatment plant assessment is based on a system of technical indicators and factors. Based on these, the assessment of the technical condition is carried out as a two-stage process, where the evaluator first determines discrete values of the factors. The point score given to these factors is then aggregated and then used to calculate the values of individual indicators, indicating the overall condition of the water treatment plant. The proposed set of assessment indicators therefore includes two types of indicators: structural–technical and technological–operational. The paper includes a case study demonstrating the use of the proposed technology to assess the technical condition of an actual water treatment plant. This methodology makes it possible to highlight critical parts of the system and, as the case may be, prioritise the elements in terms of their technical condition, which can then be used in the repair and reconstruction planning process.

Multivariate techniques, like cluster analysis (CA) and principal component analysis (PCA), were used to evaluate the spatial and temporal variability of surface water quality in a large neotropical hydroelectric reservoir (Nova Ponte Reservoir). The dataset, obtained during the period of 1995–2011 from the Energy Company of Minas Gerais State (CEMIG), contains 14 parameters surveyed quarterly in 14 sites, at different depths. The CA grouped the 14 sites in three main groups: lotic sites, half of the photic zone sites and bottom sites. Statistical tests showed that only three parameters (total dissolved solids, nitrate and chemical oxygen demand) have no significant difference between cluster groups. The PCA results showed temporal changes of the water quality in all groups, illustrating modifications to the importance of the parameters over time. PCA also revealed the major causes of water deterioration from 1995 to 2005 were related to agricultural and livestock activities. Currently, the water quality parameters related to organic pollution are also highlighted. Generally, this study shows that possible optimization of the monitoring network should consider temporal variation of water quality parameters.

There are debates about whether rainwater is suitable as drinking water. A serious shortcoming of the debate is that there are differences in the design and management of rainwater harvesting (RWH) systems. This study is based on the performance of two RWH systems that are used for drinking purposes at a kindergarten and a primary school in Cu Khe, Vietnam. Each system comprised a painted galvanized iron roof, a first-flush diverter, two stainless steel tanks connected in series, a calmed inlet, mosquito screens on open holes, PVC pipelines, filter cartridges, and a UV sterilizer. During 18 months, stored rainwater was sampled five times, and treated rainwater was sampled four times. Twenty-three water quality parameters were analyzed, including pH, total dissolved solids, turbidity, nitrate, nitrite, ammonia, hardness, arsenic, iron, cadmium, nickel, chromium, manganese, mercury, selenium, lead, zinc, Escherichia coli , and total coliform. It was found that all the physicochemical qualities of the stored rainwater, prior to treatment, satisfied the World Health Organization (WHO) drinking water guidelines. After physical filtration and UV sterilization, all parameters, including microbiological indicators, satisfied the WHO drinking water guidelines. Further management strategies to stabilize water quality were discussed.

The presence of the toxic cyanobacteria and cyanotoxin, microcystin-LR (MC-LR) and other cyanotoxins, in drinking water sources poses a serious risk to public health. Iron based technologies using magnetic zero-valent iron nanoparticles (nZVI) and ferrate ion (Fe VI O 4 2− , Fe(VI)) represent greener approaches to remove cyanobacteria and degrade MC-LR in water. This paper reveals that nanoparticles of zero valent iron (nZVI) can destroy cyanobacteria in the source water and may play a preventive role in terms of the formation of cyanobacterial water blooms by removing nutrients like phosphate. Results on MC-LR showed that Fe(VI) was highly effective in removing MC-LR in water. Products studies on the oxidation of MC-LR by Fe(VI) demonstrated decomposition of the MC-LR structure. Significantly, degradation byproducts of MC-LR did not contain significant biological toxicity. Moreover, Fe(VI) was highly effective for the degradation of MC-LR in lake water samples. Mechanisms of removal and destruction of target contaminants by nZVI and Fe(VI) are discussed.

Recognizing the composite correction program (CCP) has been successful in improving drinking water quality in the USA, the Ministry of Environment (MoE) of Korea has initiated a similar program since 1998. After three years' work, the research team has proposed an evaluation program. Water treatment plants have been classified into four groups based on their capacities because this has best represented current standings of the plant. Group 1 consists of small plants having a capacity of less than 5,000 m 3 /day. The plants in Group 4 have capacities of more than 100,000 m 3 /day. Group 2 consists of small to medium sized plants of 5,000-50,000 m 3 /day, whereas the plants in Group 3 have capacities between 50,000 m 3 /day and 100,000 m 3 /day. The evaluation documents and the treatment goals for each group also have been established in consideration of manpower and characteristics of the facilities. The disinfection goal has been set up to ensure 0.5 log removal of Giardia regardless of the group, whereas the turbidity goal has been differentiated from 0.1 NTU to 0.5 NTU. A flow chart and a detailed inspection list identifying the vulnerable points of the plant have been prepared to help the operators to know how best to improve the performance. The education programs for operators also have been practiced. The MoE has prepared a quantitative evaluation list to score water treatment plants by their capacities, facilities, manpower and the local government's financial supports. The MoE has graded water treatment plants nationwide and local governments have been ranked by the plants in their areas. The resulting grades have been announced annually so that community citizens knew where their community was positioned and how much attention their local government has paid to the waterworks. The performance evaluation program strongly backed up by the MoE is going to be spread out nationwide step-by-step. Thus, things are happening in Korea. However, some of the concepts and principles could be referred to the countries that are planning to introduce a similar program.