Peter J. Coombes

University of Newcastle, Newcastle, New South Wales, Australia

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Publications (45)36.28 Total impact

  • A C Morrow, R H Dunstan, P J Coombes
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    ABSTRACT: Entry of contaminants, such as metals and non-metals, into rainwater harvesting systems can occur directly from rainfall with contributions from collection surfaces, accumulated debris and leachate from storage systems, pipes and taps. Ten rainwater harvesting systems on the east coast of Australia were selected for sampling of roof runoff, storage systems and tap outlets to investigate the variations in rainwater composition as it moved throughout the system, and to identify potential points of contribution to elemental loads. A total of 26 elements were screened at each site. Iron was the only element which was present in significantly higher concentrations in roof runoff samples compared with tank tap samples (P<0.05). At one case study site, results suggested that piping and tap material can contribute to contaminant loads of harvested rainwater. Increased loads of copper were observed in hot tap samples supplied by the rainwater harvesting system via copper piping and a storage hot water system (P<0.05). Similarly, zinc, lead, arsenic, strontium and molybdenum were significantly elevated in samples collected from a polyvinyl chloride pipe sampling point that does not supply household uses, compared with corresponding roof runoff samples (P<0.05). Elemental composition was also found to vary significantly between the tank tap and an internal cold tap at one of the sites investigated, with several elements fluctuating significantly between the two outlets of interest at this site, including potassium, zinc, manganese, barium, copper, vanadium, chromium and arsenic. These results highlighted the variability in the elemental composition of collected rainwater between different study sites and between different sampling points. Atmospheric deposition was not a major contributor to the rainwater contaminant load at the sites tested. Piping materials, however, were shown to contribute significantly to the total elemental load at some locations.
    Science of The Total Environment 09/2010; 408(20):4542-8. · 3.26 Impact Factor
  • A R Martin, P J Coombes, R H Dunstan
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    ABSTRACT: Chemical qualities of harvested rainwater were assessed at two residential study sites on the east coast of Australia in relation to coastal proximity and surrounding land uses over the course of a winter and summer month. Daily rainwater samples were collected from the base outlet and surface levels of stored water for chemical analyses. High resolution inductively coupled plasma-mass spectrometry (ICP-MS) was used to analyse 26 elements in all samples. The summer sampling regime for the industrial coastal Site 1 was dominated by wind gusts originating from the east with a total average elemental load of 25,900+/-17,000 microg/L compared to the significantly lower 10,600+/-3,370 microg/L measured during the winter month, where 84% of wind gust events originated from the west. Data for the inland Site 2, with no proximity to industry, revealed no significant changes in total average loads between the winter (4,870+/-578 microg/L) and summer (4,760+/-2,280 microg/L) months. The most abundant elements found at both sites included Na, K, Mg, and Zn. The rainwater storages at Site 2 fed from a relatively new concrete tiled roof catchment had significantly lower pH and conductivity measurements compared with those at Site 1 with an old galvanised iron roof catchment. It was concluded that seasonal differences in harvested water quality were likely influenced by prevailing wind direction and external influences such as surrounding land uses and proximity to the coast.
    Water Science & Technology 01/2010; 61(1):25-36. · 1.10 Impact Factor
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    ABSTRACT: Microbial properties of harvested rainwater were assessed at two study sites at Newcastle on the east coast of Australia. The investigation monitored daily counts of heterotrophic bacteria (HPC), total coliforms and E. coli during a mid-winter month (July). Immediately after a major rainfall event, increases in bacterial loads were observed at both sites, followed by gradual reductions in numbers to prior baseline levels within 7 days. Baseline HPC levels ranged from 500-1000 cfu/mL for the sites evaluated, and the loads following rain peaked at 3590-6690 cfu/mL. Baseline levels of total coliforms ranged from 0-100 cfu/100 mL and peaked at 480-1200 cfu/100 mL following rain. At Site 1, there was no evidence of E. coli loading associated with the rain events assessed, and Site 2 had no detectable E.coli colonies at baseline, with a peak load of 17 cfu/100 mL following rain which again diminished to baseline levels. It was concluded that rainfall events contributed to the bacterial load in rainwater storage systems, but processes within the rainwater storage ensured these incoming loads were not sustained.
    Journal of Environmental Monitoring 01/2010; 12(1):255-60. · 2.09 Impact Factor
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    S. A. Lucas, P. J. Coombes, A. K. Sharma
    Water Science & Technology Water Supply 01/2010; 10(1).
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    ABSTRACT: The concept that domestic rainwater storage tanks may host sustainable microbial ecosystems has not previously been addressed. The bacterial diversity, cultivated from more than 80 samples from 22 tanks at various locations across eastern Australia, is presented here as prima facie evidence for the potential operation of a functional micro-ecology within rainwater storage systems. Cultivated isolates were found to comprise members of four major bacterial divisions; Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes, including more than 200 species from 80 different genera. The pattern of abundance distribution was typical of that observed in most natural communities, comprising a small number of abundant taxa and a multitude of rare taxa, while the specific composition resembled that previously described in a number of natural aquatic systems. Although Proteobacteria from alpha, beta and gamma sub-classes were dominant, a set of core taxa comprising representative genera from all four phyla could be identified. Coliform and other species specifically associated with faecal material comprised <15% of the species identified, and represented <1.5% of total average abundance. The composition of the cultivated populations and scope of diversity present, suggested that rainwater tanks may support functional ecosystems comprising complex communities of environmental bacteria, which may have beneficial implications for the quality of harvested rainwater.
    Science of The Total Environment 07/2009; 407(19):5206-15. · 3.26 Impact Factor
  • Steven Lucas, Peter Coombes
    H2009: Proceedings of H2009, the 32nd Hydrology and Water Resources Symposium, Newcastle, NSW; 01/2009
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    S. A. Lucas, P. J. Coombes
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    ABSTRACT: This paper provides monitoring of water use between January 2008 and December 2008 at a residential home in Hornsby Heights (NSW) that employs large architecturally-designed under-floor rainwater storages (4 x 16 kL cells). Water demand was continuously monitored using smart water meters to reveal intra-daily water use patterns. Based on this data, the PURRS model was used to continuously simulate the performance of the rainwater harvesting system using long-term climate records (at 6-minute timesteps) at the Hornsby House. The attributes of the rainwater harvesting strategy at this house was then applied to Adelaide, Brisbane, Canberra, Darwin, Hobart, Melbourne, Sydney and Perth; and simulated using PURRS with appropriate water demands (3-person household) and long-term rainfall records. Results indicate significant mains water savings and stormwater management benefits, such as reduced requirements for on-site detention (OSD), can be obtained using large architecturally-designed under-floor rainwater storages in all Australian capital cities.
    01/2009;
  • Steven Lucas, Peter Coombes
    H2009: Proceedings of H2009, the 32nd Hydrology and Water Resources Symposium, Newcastle, NSW; 01/2009
  • Steven Lucas, Peter Coombes, AK Sharma
    H2009: Proceedings of H2009, the 32nd Hydrology and Water Resources Symposium, Newcastle, NSW; 01/2009
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    ABSTRACT: Deriving maximum economic and water savings benefits from rainwater harvesting in the urban environment requires the use of rainwater for internal applications, including showering/bathing, laundry and toilet fl ushing. Widespread use of rainwater for these applications has been hindered by uncertainty over quality and perceptions of health risk. This study examined the presence and abundance of the faecal indicators E. coli, enterococci and total coliform in over 100 water samples collected from rainwater tanks in eastern Australia. A large proportion of samples were compliant with the requirements of mains water drinking standards, especially among those collected via a hot water system, while almost universal compliance with bathing water quality standards was observed. Indicator species were found to represent a very small proportion of total bacterial contamination and no signifi cant correlation between faecal indicator counts and heterotrophic plate counts was observed. Furthermore, enterococci were not signifi cantly correlated with the other indicator groups. On average, heterotrophic counts were found to be dominated by Pseudomonas spp and several other widely distributed environmental organisms. The implications of these fi ndings with regard to the scope of domestic rainwater use in the urban environment, and the diffi culty in achieving reliable risk assessment, have been discussed.
    Australian Journal of Water Resources 01/2008; 12(2):143-149.
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    ABSTRACT: In this study, 12 catchments sites located along the north coast of New South Wales in Australia were grouped into the four categories of septic, cattle, sewage treatment plant (STP) and forested sites via cluster analysis based on their land use patterns. Water samples from all these sites were collected between October 2004 and June 2006 at a regular monthly interval and within 48 h of rain events. The samples were analyzed for bacterial counts including faecal coliform and total coliform; faecal sterols including coprostanol, epicoprostanol, cholesterol, cholestanol, 24-ethylcoprostanol, campesterol, stigmasterol and beta-sitosterol; and the elements including Na, Rb, Sr, Ag, Cd, Sn, Cs, Ba, Hg, Tl, Pb, Bi, U, Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, K, As, Se, P and Mo. Over the course of the sampling period, the STP site had the highest average coprostanol level of 1693+/-567 ng/L which was significantly higher (p<0.05) than the septic sites (190+/-71 ng/L), the cattle sites (163+/-94 ng/L) and forested sites (14+/-4 ng/L). As expected, the forested sites had significantly lower average level of faecal coliforms (373+/-87 cfu/100 mL) compared with the STP (1395+/-574 cfu/100 mL), septic (1243+/-494 cfu/100 mL) and cattle sites (535+/-112 cfu/100 mL). The concentrations of coprostanol were not correlated with the numbers of faecal coliform bacteria when the entire data set was evaluated. The forested sites generally had the lowest average levels of elemental compositions, with significantly lower levels noted for Na, U, Mg, V, Cu, Sr, K, As, P and Mo, whereas Fe was the only element notably higher in the forested sites. Temporal and rain events analyses of the data set revealed that elevated levels of both coprostanol and faecal coliforms were not exclusive to rain events. The average coprostanol levels in rain event samples at each site were not significantly different compared with the corresponding dry event samples. Conversely, faecal coliform numbers increased by 2-4 times in rain events samples from septic, cattle and forested sites, but did not alter in the STP site. Multivariate analyses identified coprostanol and Sr as major contributing factors for the discrimination of septic, cattle, STP and forested sites for both rain and dry events samples. It was clear that each land use type of catchment could be characterized by biochemical, bacteriological and elemental parameters.
    Water Research 09/2007; 41(16):3655-66. · 4.66 Impact Factor
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    ABSTRACT: Faecal samples from humans, herbivores, carnivores and birds as well as samples from septic tanks and effluents from a sewage treatment plant (STP) were extracted and analyzed by gas chromatography-mass spectrometry for faecal sterols including coprostanol, epicoprostanol, cholestanol, cholesterol, stigmasterol, campesterol, 24-ethylcoprostanol and beta-sitosterol. Coprostanol was observed in the highest concentrations from the human derived samples, but it was also present in substantial quantities in a range of herbivores. There was no unique marker of human faecal contamination. Multivariate analyses revealed that the faecal sterol profiles were significantly different between the four groups of animals (Wilks' lambda=0.007, P<0.002), and coprostanol and 24-ethylcoprostanol were the major discriminant factors. However, when faecal samples were mixed, the confounding of faecal sterol levels prevented accurate identification of contributing species. Conversely, faecal sterol ratios were highly efficient at identifying which mixtures contained human contribution, but could not appropriately determine percentage contributions of sources.
    Water Research 09/2007; 41(16):3691-700. · 4.66 Impact Factor
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    ABSTRACT: Water samples from sites potentially impacted by septic tanks, cattle, sewage treatment plant (STP) and natural forests were collected at regular monthly intervals and within 48 h of rainfall events between October 2004 and June 2006. All samples (n=296) were analysed for faecal coliforms and faecal sterols including coprostanol, epicoprostanol, cholestanol, cholesterol and 24-ethylcoprostanol. Faecal sterol ratios were used to assign human and/or herbivore contamination sources and to estimate their percentage relative contributions in water samples. The catchments had significantly different profiles of designated contamination origins (p<0.05), which were consistent with land use patterns. The STP impacted site had the highest incidence of human contamination assignations and the highest mean levels of coprostanol, whilst the forested site had the highest incidence of uncontaminated samples and the lowest mean concentration of coprostanol. Coprostanol concentrations were not always correlated with faecal coliform counts.
    Water Research 08/2007; 41(16):3667-74. · 4.66 Impact Factor
  • P J Coombes, M E Barry
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    ABSTRACT: The use of domestic rainwater tanks with back up from mains water supplies in urban areas can produce considerable reductions in mains water demands and stormwater runoff. It is commonplace to analyse the performance of rainwater tanks using continuous simulation with daily time steps and average water use assumptions. This paper compares this simplistic analysis to more detailed analysis that employs 6 minute time steps and climate dependent water demand. The use of daily time steps produced considerable under-estimation of annual rainwater yields that were dependent on tank size, rain depth, seasonal distribution of rainfall, water demand and tank configuration. It is shown that analysis of the performance of rainwater tanks is critically dependent on detailed inputs.
    Water Science & Technology 01/2007; 55(4):125-33. · 1.10 Impact Factor
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    ABSTRACT: Samples from a variety of rainwater tanks and mains water supplies from different regions in the Australian states of NSW, QLD, VIC, and SA, were analysed for a range of elements by ICP-MS. Investigations were performed to determine whether the distributions of elements in stored rainwater varied depending on urban or rural location and roof type (Pre-Painted steel, 55% Al-Zn alloy coated steel, Cement Tiles, or Galvanised Iron). Differences in elemental composition in stored tank water and mains water samples were also investigated. Mains water samples were found to contain significantly higher concentrations of sodium, strontium, barium, magnesium, and molybdenum, and significantly lower concentrations of manganese and zinc compared with tank water samples (P
    01/2007;
  • L. Cui, M. Thyer, P. J. Coombes, G. Kuczera
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    ABSTRACT: The emerging integrated water cycle management paradigm places a greater emphasis on demand-side management at the household/cluster scale than traditional design approaches. This is the motivation for the development of models that capture the dynamics of household water use at smaller spatial and temporal scales than those traditionally adopted for design of water cycle infrastructure. This study utilised data from Hunter Water Corporation (HWC) that consisted of 161 houses with measurements of monthly indoor water use over a period of 10 years. Temporal analysis of the dataset indicates that household indoor water use is mainly influenced by the household occupancy. Two major sources of occupancy dynamics were hypothesized; permanent long-term changes due to occupants permanently moving in/out and temporary short-term changes due to the occupants going on holidays and/or having visitors. In this study, a household indoor water use model was developed in which a hidden Markov model (HMM) framework was used to identity the long-term dynamics of household occupancy. The preliminary model diagnostics indicate that a reasonable fit was obtained for up to 40% of the households. Further challenges include identifying suitable drivers of the long- term dynamics and capturing the short-term dynamics evident in the data. Water authorities are facing considerable challenges to satisfy the increasing demand (due to population growth) on their water supply systems in the face of the potential for decreased yield due to climate change/variability and the tighter environmental constraints on developing new water sources. This is combined with the additional pressure of the high economic cost of rehabilitation and replacement of aging water infrastructure, which in many areas is reaching the end of its design life and the negative impact of current systems on the natural ecosystems, particularly the receiving waters. Coombes and Kuczera (2002) advocated that traditional centralized approach to water resource system design and management resulted in missed opportunities and that the optimum use of centralized and decentralized approaches needs to be based on a systems approach to evaluate system performance against multiple objectives. The concept of a systems approach is simple to understand, however, as Coombes and Kuczera (2002) note "the devil is in the detail." The current design practices and models which have evolved based on the traditional centralized paradigm are inadequate when adopting a systems approach. The emergence of the paradigm of integrated water cycle management (IWCM) places an emphasis on demand-side management, as well as supply-side management, utilisation of non-traditional water resources, and the concept of fit-for-purpose and decentralisation (Coombes and Kuczera 2002). Effective and efficient design using the IWCM paradigm relies on a greater understanding of the dynamics of household water use at spatial and temporal scales smaller than those traditionally adopted for such design work. For instance, the majority of demand data used to date in IWCM programmes describes the dynamics of water use over large regional scales and at aggregated (typically annual) temporal scales. In contrast, there is limited information or understanding of the dynamics of water use at the household scale. The design of water supply and wastewater infrastructure is generally based on peak demand or wastewater flow volumes (for example; peak day demand, peak hour demand, peak dry weather flow and peak wet weather flow). The advent of the IWCM paradigm implies that future water infrastructure systems will be designed probably quite differently from the
    01/2007;
  • 01/2007; University of Newcastle.
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    ABSTRACT: The composition of dominant bacterial populations, along with selected elemental characteristics, were assessed from direct precipitation, roof runoff, and two sampling points within a rainwater storage tank located at an inner suburb of Newcastle, on the east coast of Australia. Direct rainfall was found to contain 20±13cfu/mL of bacteria with no detectable cadmium, lead or mercury, while the tile roof was found to be a contributor of lead contamination at 0.030±0.031mg/L in the collected runoff that persisted within the water column of the rainwater tank at 0.020±0.012mg/L. The surface skim layer of the tank provided the highest variability of recoverable bacteria with 2261±3917cfu/mL, while the tank's tap outlet averaged 1345±1361cfu/mL. Corresponding lead levels averaged 0.022mg/L at the surface and 0.018mg/L at the tap outlet. Environmental bacteria including Pseudomonas, Bacillus, Pantoea and Enterobacter species were among the most predominant organisms consistently recovered from sampling collections. E. coli was only detected in one out of 8 events of the roof runoff collections at 18cfu/mL and twice out of 6 samples at 1cfu/mL from the tank's tap outlet. The data suggested that the major sources of bacterial and elemental loads were derived from dislodgement of accumulated deposits on the catchment surfaces. Faecal coliform bacteria were negligible in this rainwater harvesting system. Despite evidence of bacterial and chemical loading via catchment processes, the tank outlet samples showed that bacterial and selected chemical components were reduced, suggesting active processes of contaminant regulation within the tank.
    01/2007;
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    ABSTRACT: Perceptions of the quality of roof harvested rainwater remain an impediment to widespread implementation of rainwater tanks on urban allotments. Previous literature reports on roof water quality have given little consideration to the relative significance of airborne environmental micro-organisms to roof catchment contamination and the issue of tank water quality. This paper outlines the findings of a recent study into the influence of weather on roof water contamination conducted at an urban housing development in Newcastle, on the east coast of Australia. Samples of direct roof run-off were collected during a number of separate rainfall events, and microbial counts were matched to climatic data corresponding to each of the monitored events. Roof run-off contamination was found to be under the strong influence of both wind speed and direction. The preliminary findings of an investigation currently under way into the microbial diversity of rainwater harvesting systems have also been presented. The results indicate that the composition of organisms present varied considerably from source to source and throughout the collection system. In all cases, evidence of faecal contamination was found to be negligible. The implications of these findings to the issues of tank water quality, health risk analysis and monitoring protocols have been discussed.
    Water Science & Technology 01/2007; 55(4):245-53. · 1.10 Impact Factor
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    13th International Rainwater Catchment Systems Conference and 5th International Water Sensitive Urban Design Conference, 21-23 August 2007, Sydney, Australia; 01/2007