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First flush is a common phenomenon in urban runoff pollution. Typical cement roof and asphalt road runoff in Beijing, China were monitored for 2 years. Based on the M(v) curve, the suspended solids (SS), chemical oxygen demand (COD), total phosphorus (TP) and particulate phosphorus in cement roof runoff presented a stronger first flush than those in asphalt road runoff. The first flush volume (VFF) of SS, COD, total nitrogen (TN) and TP in asphalt road runoff differed slightly from the cement roof. There were also differences in the first flush assessment depending on which method was used. We proposed a new method based on the runoff depth versus pollutant cumulative mass curve. According to the national standards in China (VFF = 3 mm), various masses of different pollutants, such as 91.42 ± 9.80% (cement roof) and 78.49 ± 19.41% (asphalt road) of SS and 86.85 ± 13.54% (cement roof) and 72.80 ± 25.79% (asphalt road) of COD, can be effectively controlled, but our mass control efficiencies were 55.91%–66.65% when VFF = 1 mm. The new method proposed in this study provides an alternative approach for assessing runoff pollution control efficiency of different VFF. HIGHLIGHTS SS, COD, TP and PP exhibited a stronger first flush in cement roof runoff than in asphalt road runoff by M(v) method.; VFF of SS, COD, TN and TP in asphalt road runoff differed slightly from the cement roof.; Differences were found in the first flush assessment results between M(v) and VFF methods.; A new method based on the runoff depth versus pollutant cumulative mass curve was proposed.

Bioretention structures such as planter boxes, swales and rain gardens are being increasingly utilized in built landscapes as a strategy to attenuate both stormwater flows and contaminant loads. Copper (Cu) roofing materials contribute significantly higher mass loads of dissolved Cu per unit area than other surfaces such as parking lots and roadways. While a recent study demonstrated that conventional bioretention media can remove greater than 90% of Cu from copper roof runoff, the median Cu concentrations at the point of discharge from bioretention structures (66 μg L-1) still did not achieve Cu concentrations in stormwater discharges sought in some jurisdictions (for example, < 14 μg L-1). Consequently, commercially available soil amendments were assessed to improve bioretention Cu removal. The ability of biochar, greensand, and zeolite to improve Cu removal was evaluated in laboratory column studies. Additionally, the performance of zeolite as an underlayer amendment was evaluated in bioretention planter boxes treating stormwater from a picnic shelter with a partitioned copper roof. Cu was measured in the planter box influent and effluent. The field setup included 2 control planter boxes containing only standard bioretention media and 2 amended with the zeolite underlayer. Samples from ten storms were collected with flow-weighted composite sampling. Total Cu in composite samples of the influent waters ranged from 445 to 1683 μg L-1 and had a median concentration of 934 μg L-1. Total Cu in the effluent from the control planter boxes ranged from 10 to 64 μg L-1, with a mean of 29 μg L-1. Total Cu in effluent from the zeolite amended planter boxes ranged from 4 to 44 μg L-1 with a mean of 18 μg L-1. Attenuation in the control planter boxes ranged from 90 to 99% with a median of 93.4% by concentration and ranged from 95 to 99% with a median of 97.5% in the zeolite amended planter boxes.

Runoff water is an important medium transporting various types of pollution originating from the atmosphere and washed out from roofing materials. The study presents a quality assessment of runoff from different roofs in the context of trace metal concentrations. The analysed rooftops were covered with copper, tar paper and ceramic tile. The quality of the rain water collected at the same time satisfies the demands of the first grade of cleanliness according to (Journal of Laws, 2016 item1187). The highest content of copper was leached from the copper roof, containing 10.23 mg∙dm-3. In the case of zinc, the highest concentration of 15.52 mg∙dm-3 was present in the runoff from the roof covered with thermally bonded tar paper. The amount of trace metals in the ceramic roof runoff was the lowest and only for zinc slightly exceeded 1.47 mg∙dm-3 – the value determined for II class of purity. In the paper, the different levels of heavy metals leaching from different roofing materials have been confirmed.

Understanding the sources of chemical components in roof runoff can help to prevent water quality problems in rooftop rainwater harvesting. To identify the contribution of wet deposition to the mass of components in roof runoff, the samples from air, rainwater, dust buildup and roof runoff were collected from an urban site in Shenzhen of China in 2011–2012. The results indicate that: (1) wet deposition has a dominant contribution to the mass of total organic carbon (TOC), NH4+, NO3–, Cl– and organic acids in the roof runoff, while the mass of NH4+, acetic acid and formic acid in the roof runoff may be greatly reduced by the neutralization between the components with alkaline dust buildup on the rooftop; and (2) wet deposition partially contributes to the mass of Na+, K+, Mg2+, Ca2+, F– and SO42– in the roof runoff, while other factors like dust buildup on the rooftop and chemical reactions also have a non-negligible impact. Furthermore, TOC, NH4+, NO3– and organic acids in the wet deposition are mainly influenced by the atmospheric pollution due to fast increase in fossil fuel consumption (e.g. vehicle emissions). Therefore, the effects of wet deposition should be carefully considered for rooftop rainwater harvesting in urbanized areas.

The objective of the paper is to evaluate the potential of tank-based rainwater harvesting systems in free standing houses as the source control method to mitigate peak roof runoff due to rainfall in urban areas. To this aim, the water balance simulation of the rainwater tank was carried out using both high resolution rainfall series and toilet water demand data extracted from the database of results built in a previous field campaign involving six experimental households in southern Italy. Simulations show that significant potential for runoff peak reduction exists, basically depending on the rainwater tank size and on the characteristics of the water demand in the house.

The authors set out to study the stormwater management viability of greenwalls in a simulated retention of roof runoff, using a cistern for simulated runoff to irrigate the greenwalls. By experimenting with two greenwalls of different exposures (one southeast and one northwest), this study demonstrated that the southeast facing greenwall and the northwest facing greenwall retained comparably favorable amounts to greenroof stormwater retention systems. With more and more competition for limited horizontal surface area in urbanized and urbanizing areas, the use of vertical surfaces for stormwater mitigation and evapotranspiration has attractive potential. This article presents the background, project, methods, findings, and conclusions of the study.

Roofs surfaces are frequently used to catch water for drinking in many countries, so the presence and mobilisation of material into runoff water can be an important process to consider. This paper investigates the origin and mobilisation of trace elements from roofing tiles. Our work suggests that trace elements can mobilise into roof runoff. However, lead by contrast, appears to have accumulated at the surface of tiles exposed to busy automobile traffic that used leaded fuel (confirmed by X-ray fluorescence). Although lead is relatively immobile on the tile surface, the potential for leaching by acidic rain (pH

This paper presents the findings of an 18-month study of detritus accumulation at two siphonic rainwater drainage systems installed in a building in Edinburgh. Findings are based on an analysis of data recorded from the site, and are positioned within the context of enhancing representation of the outlet loss coefficient used within both steady-state design calculations and finite-difference-based unsteady flow modelling techniques. The scope of findings reported herein is extensive but, in the main, shows how detritus accumulation not only builds relatively rapidly but also that ‘wash-through’ or ‘displacement’ occurs. Further, data suggest that detritus accumulation in the gutter, that is either wind-blown or is introduced from roof runoff, can, and does, build around the outlet with only relatively low intensity rainfall but that high-intensity rainfall events do seem to result in a direct and significant increase in blockage. An indication of the impact upon performance, assessed using simulation software, is also presented. Practical application: This paper reports patterns of detritus accumulation at on-site siphonic rainwater outlets. Changes in detritus ‘categories’ are mapped to corresponding weather data and conclusions drawn on influencing factors. The paper therefore yields key information for building owners/operators on the extent of detritus accumulation at siphonic system outlets. Outcomes also inform designers of the potential shift in loss coefficient and flow performance post-installation.

The zinc and copper content of roof runoff could originate from different sources such as dry and wet deposition and the corrosion of the material. The zinc runoff rate from a galvanized surface depends on the corrosion products formed during the dry days, the rain intensity and roof slope, which determinates the contact time. In the present study the contact time dependence of zinc rate and the re-dissolution of the zinc were investigated with steeping tests and a pilot study. The average zinc runoff measured in the first 2.8 l of runoff was 3.8 mg m(-2) (1.1-8.4 mg m(-2)), while in the following samples 1.2 mg m(-2) were detected. These results are in accordance with the 5-10 min, and 40-60 s contact time laboratory steeping test, respectively, which are realistic. The estimated specific yearly zinc runoff rate was 0.7 g m(-2)y(-1), while the dry and wet deposition rate of copper was 0.009 mg m(-2)d(-1) and 0.053 mg m(-2)storm(-1) respectively. The re-dissolution of the zinc from the evaporated then re-filled samples of leaching tests with high initial zinc content was just 60% after 60 min.

Rainwater harvesting (RWH) systems provide the dual, but often opposing, benefits of acting as alternate water supply sources and providing detention/retention of roof runoff that would otherwise become stormwater runoff. A major challenge that exists when using a RWH system to simultaneously accomplish stormwater and water-conservation benefits in nonarid regions is that these systems are often underutilized, thus remaining full a large portion of the time. For a system to mitigate stormwater runoff, however, there must be sufficient room available in the tank to store a runoff event. Two novel approaches were implemented to improve the ability of RWH systems to serve as both water-conservation practices and stormwater-management practices: an active release technology and a passive release technology. Two locations in Craven County, North Carolina, had RWH systems installed to capture roof runoff and store it for nonpotable uses. One system was equipped with the passive release mechanism, which ...

International audience; The water balance of a four-people family rainwater harvesting system was calculated in a case study. The experimental water saving efficiency (WSE) was calculated as 87%. A simple computer model was implemented to simulate the behaviour of the rainwater harvesting system. In general, the rainwater collector volumes predicted by the daily model had shown a good correlation with the experimental values. The difference between the experimental and the predicted values for the stored volume can be explained by the lack of maintenance of the system that can affect its performance. On the basis of a long-term simulation of 20-year rainfall data, the following parameters were calculated: rainfall, water demand, mains water, rainwater used, over-flow and WSE. The collection of rainwater from roofs, its storage and subsequent use for toilet flushing can save 42 m3 of potable water per year for the studied system. The model was also used to find the optimal size of the tank for the single-family household: a storage capacity of approximately 5 m3 was found to be appropriate. The storage capacity and tank size were distinguished. The importance to take into account the dead volume of the tank for the sizing was indeed highlighted.

Although rainwater recycling has been subjected to tax exoneration since 2006 for individuals, its use was approved, for interiors only, in August 2008. However, little consideration has been given to the roof runoff quality, its potential use, and to the maintenance procedures of the roof surface and the runoff recuperation tank. The products used for cleaning and maintenance of rooftops may be a major source of organic pollutants in the collected waters. After listing the products, four possible treatments were identified: primary cleaning, fungicide treatment, waterproofing and paint. Some of these specific products include a biocide action. Quaternary ammonium compounds and isothiazolinone derived compounds have been underlined. These both molecules are very toxic for aquatic organisms, with EC50 down of 1 mg.L-1. Moreover an investigation work shown that fungicide treatment and waterproofing are the two most current practices. Finally, it has been brought to light that several treatments are operated by unprofessional people, hence neither the products nor the methods used are easily recognizable.

On-site infiltration of a copper roof runoff may contribute to deterioration of the ground and ground water. To avoid such a negative effect the performance of two different technical systems, equipped with four different barrier materials, regarding copper elimination was examined in a field study. During the period March 2004 to January 2005, 16 rain events were examined. Copper concentrations between 200 and 11,000 μg/L in the roof runoff during a rain event were observed. The cover material of the roof and the drainage system were responsible for the high concentrations of copper in the roof runoff. It was evident that roof aspects facing towards the wind direction were receiving higher rainfall, thus were establishing higher copper runoff rates. The retention facilities have reached a performance of up to 97% regarding copper elimination.

There has been a growing interest, especially in developing countries, in rooftop rainwater harvesting as an alternative source of drinking water. This paper reviews the available information on the water quality of rooftop rainwater harvesting systems. Various factors that affect the physico-chemical and microbiological quality of harvested water are discussed. Different contaminants including heavy metals and trace organic pollutants in the roof runoff reported from different parts of the world are compared. The review shows that the quality of harvested water from roof catchments often does not meet the drinking-water guideline values. Most of the studies reveal that harvested water is heavily contaminated microbiologically by a variety of indicator and pathogenic organisms unless special care is taken during collection and storage of rainwater. Heavy metals and trace organics could also pose problems in some cases. The review thus indicates that the purity of rainwater harvested from rooftops should not be taken for granted, and analysis of the harvested water especially for microbiological contamination should be undertaken. Appropriate treatment of collected rainwater would be necessary to make the harvested rainwater fit for drinking. The review also shows the need for further research on proper design and maintenance strategies to minimise contamination of roof-collected rainwater supplies.

Direct infiltration of roof runoff into the ground may pose a potential risk of soil and groundwater contamination. The performance of two different barrier materials for the retention of zinc from roof runoff of an eleven year old zinc roof was examined in a field study. As barrier materials geotextile and clinoptilolite were applied. Automatic samplers were used to take samples both at the inlet and at the outlet of the retention facility. Samples of twenty rain events were examined. Zinc was detected in the roof runoff in concentrations of up to 25 mg/L, and lead which originates from the tin-solder was present in concentrations of up to 84 μg/L. Under most circumstances, a first flush could be observed for the analysed substances. No retention of heavy metals was observed, where only geotextile was used as a barrier material. The clinoptilolite filter was able to adsorb up to 97 % of zinc from the roof runoff. Elimination von Schadstoffen aus Ablaufen eines Zinkdaches bei der Regenwasserversickerung Die Regenwasserversickerung von Dachablaufwassern in den Untergrund kann ein Risiko der Kontamination von Boden und Grundwasser beinhalten. Die Eliminationsleistung zweier unterschiedlicher Barrierematerialien hinsichtlich Zink aus den Ablaufen eines elf Jahre alten Zinkdaches wurde untersucht. Als Barrierematerialien wurden Geotextil und Klinoptilolith getestet. Mit automatischen Probenehmern wurden Proben im Zulauf und im Ablauf des Filters genommen. Es wurden zwanzig Regenereignisse beprobt. In den Dachablaufen wurden Zinkkonzentrationen bis zu 25 mg/L gefunden sowie Blei, das aus den Verbindungen der einzelnen Dachplatten stammt, in Konzentrationen bis 84 μg/L. Ein First Flush konnte unter den meisten Umstanden fur die untersuchten Wasserinhaltsstoffe aufgezeigt werden. Das Ruckhaltevermogen des Geotextil-Filtersacks bezuglich der Schwermetalle erwies sich als sehr gering oder nicht vorhanden. Der Klinoptilolith-Filter hingegen erreichte bei der Elimination von Zink eine Effektivitat von bis zu 97 %.

There are no any feasible theoretical methods for determining the initial removal of the roofwater now, which restrains the development of the roofwater utilization to some extent. The main sources of various pollutants in the roofwater and the variation of their concentrations are analyzed with the relevant sampling and testing. Based on the data of turbidity measured from five rainfall processes occurred in Jinan of University, the parameters of the accumulation-washout model for turbidity are estimated, and then the application scope of the model is determined with the relevant verification. The relationship between the turbidity removal rate and the pollutant washout index as well as the roof runoff coefficient are derived, which provides a practical calculation method for determining the initial removal of the roofwater. Keywordsroofwater; turbidity; accumulation-washout model; initial removal.

In this study, the development and performance of rainwater utilisation systems in Germany are described. Initially the operational characteristics of the different types of rainwater utilisation systems are explained. The objective of the modelling-based investigations is to quantify the effects of rainwater usage systems on the urban drainage system. On the basis of a long-term simulation of 10 years rain data, the following parameters were calculated: tank volumes, covering efficiency, drinking water savings, overflow occurrence, overflow volumes, overflow reduction, recurrence time of overflows. The water balance of a one-family house and a multi-storey building in Bochum was calculated in a case study.

To prevent overloading of sewer systems and to ensure sufficient recharging of the groundwater underneath sealed urban areas, collection and artificial infiltration of roof runoff water has become ...

International audience; The quality of stored roof runoff in terms of pesticide pollution was assessed over a one-year period. Two tanks, located at a rural and suburban site, respectively, were sampled monthly. The two studied collection surface were respectively a tile slope roof and a bituminous flat roof. Four hundred and five compounds and metabolites were screened using liquid and gas chromatography coupled with various detection systems. Principal Component Analysis was applied to the data sets to elucidate patterns. At the rural site, two groups of compounds associated with two different types of agriculture, vineyard and crops, were distinguished. The most frequently detected compound was glyphosate (83%) which is the most commonly used herbicide in French vineyards. At the suburban site, quantified compounds were linked to agriculture rather than urban practices. In addition, all samples were contaminated with mecoprop which is a roof-protecting agent. Its presence was attributed to the nature of roofing material used for rainwater collection. For both sites, the highest number and concentrations of compounds and metabolites were recorded at the end of spring and through summer. These results are consistent with treatment periods and higher temperatures. (C) 2013 Elsevier Ltd. All rights reserved.

Urban runoff and household wastewater samples were analysed for PCDD/F. The concentrations in street runoff lay between 1 and 11 pg TEQ/L. A roof runoff sample was less contaminated (< 1.7 pg TEQ/L), with levels at most a factor of 2 higher than in a parallel rain water sample. Household wastewater showed higher PCDD/F concentrations of up to 14 pg TEQ/L. The homolog profile agreed well with the profile found in sewage sludge samples. Washing machine effluent is a major source of PCDD/F in household wastewater. PCDD/F were also quantified in shower water.

International audience; The quality of harvested rainwater used for toilet flushing in a private house in the south-west of France was assessed over a one-year period. Twenty-one physicochemical parameters were screened using standard analytical techniques. The microbiological quality of stored roof runoff was also investigated and total flora at 22°C and 36°C, total coliforms, Escherichia Coli, enteroccocci, Cryptospridium oocysts, Giardia cysts, Legionella species, Legionella pneumophila, Aeromonas, and Pseudomonas aeruginosa were analysed. Chemical and microbiological parameters fluctuated during the course of the study, with the highest levels of microbiological contamination observed in roof runoffs collected during the summer. Overall, the collected rainwater had a relatively good physicochemical quality but variable, and, did not meet the requirements for drinking water and a microbiological contamination of the water was observed. The water balance of a 4-people standard family rainwater harvesting system was also calculated in this case study. The following parameters were calculated: rainfall, toilets flushing demand, mains water, rainwater used and water saving efficiency. The experimental water saving efficiency was calculated as 87 %. The collection of rainwater from roofs, its storage and subsequent use for toilet flushing can save 42 m3 of potable water per year for the studied system.

The quality of surface and ground water in the Obuasi municipality is poor due to the vigorous mining activities taking place in this area. Harvesting rainwater has become an alternative source of domestic water supply to the inhabitants, but there are no reports on their quality. In this study, runoff samples were taken from four different roofing materials in three communities and analyzed for the following parameters Fe, Pb, Cd, Cr Zn, Al, NO3−, SO42-, PO42- and Cl− using standard procedures in order to determine their impact on the quality of the harvested water. The results reveal that, the type of roofing material used for the harvest did influence the quality of the runoffs. The concentrations of Pb and Cd were high in samples from asbestos and clay tiles roofing materials than that of the metal sheets. Asbestos and clay tiles roofing materials pose more environmental risk than other roofs investigated in this study, hence should not be used to harvest rainwater for domestic purposes. The orders in which the roofs are liable of releasing metals into the runoffs are: Cr (ceramic > asbestos > metal sheet), and Zn and Al (metal sheet > asbestos > ceramic tiles). Clay tiles which have rough surfaces do retain contaminants than the metal roofs which are smooth. The levels of some of the metals were above the permissible limits and are health hazards especially for the people who used the harvested water for domestic purposes.

International audience; Combined sewers receive high toxic trace metal loads emitted by various sources, such as traffic, industry, urban heating and building materials. During heavy rain events, Combined Sewer Overflows (CSO) can occur and, if so, are discharged directly into the aquatic system and therefore could have an acute impact on receiving waters. In this study, the concentrations of 18 metals have been measured in 89 samples drawn from the three pollutant Entry Pathways in Combined Sewers (EPCS): i) roof runoff, ii) street runoff, and iii) industrial and domestic effluents and also drawn from sewer deposits (SD). The aim of this research is to identify metallic markers for each EPCS; the data matrix was submitted to principal component analysis in order to determine metallic markers for the three EPCS and SD. This study highlights the fact that metallic content variability across samples from different EPCS and SD exceeds the spatio-temporal variability of samples from the same EPCS. In the catchment studied here, the most valuable EPCS and SD markers are lead, sodium, boron, antimony and zinc; these markers could be used in future studies to identify the contributions of each EPCS to CSO metallic loads.

De nombreux travaux de recherche ont montré que les matériaux de couvertures constituent une source importante de métaux dans les eaux de ruissellement urbaines. Dans le cadre de la mise en œuvre de la Directive Cadre Européenne sur l'eau (2000/60 CE), la quantification de ces émissions s'avère nécessaire, imposant le développement d'outils permettant une telle évaluation à grande échelle. L'étude porte sur un petit bassin versant urbain (assaini en réseau séparatif), sur lequel des échantillonnages ont été réalisés: retombées atmosphériques, ruissellement de chaussées, de toitures et eaux pluviales à l'exutoire du bassin. L'objectif est (1) de vérifier la contribution des matériaux de toitures aux émissions de Zn et de Pb à l'échelle du bassin et (2) de voir comment les modèles précédemment développés dans le cadre du programme de recherche TOITEAU (à l'échelle de bancs d'essais expérimentaux) peuvent être appliqués à des échelles spatiales différentes (toit et bassin versant) pour la quantification des ces émissions. Les résultats obtenus confirment la forte contribution des matériaux de toitures aux flux de Zn et Pb dans les eaux de ruissellement à l'échelle de bassin. Dans le cas du Zn, les modèles mis en place à petite échelle ont pu être transposés et validés à l'échelle du toit et du bassin versant. La transposition des modèles d'émission du plomb est plus difficile, du fait de l'estimation délicate des surfaces concernées.

Rolled zinc and copper sheets are commonly used as roofing materials and for drainage systems in countries all over the world. The use of copper as a roofing material has a long tradition in Europe back to the 16th century when copper began to be used in Scandinavian countries, originally to prevent buildings from catching fire. Zinc sheet has been used as a roofing material for over two hundred years.

In a study of the quality of runoff from roof surfaces, five individual house roofs in the city of Bayreuth, Germany, were compared with experimental roofs on the university campus and with the depositing precipitation. While the city locations all had different exposition characteristics, the campus site experienced urban background conditions without local emissions on or nearby the roofs. The concentrations of the substances under investigation showed a high degree of variability both within and in between single precipitation events. While the wet deposition load of organic micropollutants is increased by washoff of dryly deposited substances (e.g. PAH, ammonium) from the roof surfaces, the concentrations of inorganic ions like calcium were also increased by leaching from the roof material itself. For both processes, there were marked differences between the roofs studied. PAH concentrations in runoff from one roof receiving emissions from old heating systems were elevated by more than one order of magnitude. According to the source variability for the respective substances, seasonal trends could also be detected. The investigation shows that it is difficult to generalise the pollution level of roof runoff even within a small area. This has to be taken into account for the planning of alternative urban drainage systems like infiltration facilities.