How supply system design can reduce the energy footprint of rainwater supply in urban areas in Australia

In Australia rainwater tanks are used in cities to reduce demand of mains water and increase the resilience of cities to drought. Rainwater is collected in a tank and supplied to a dwelling through a small pump. Typically the energy footprint for rainwater supply (in kWh/kL) is higher than for centralised water supply, but it can also vary markedly from dwelling to dwelling (0.4-11 kWh/kL). This study aimed to understand how the design of the rainwater supply system from the collection tank to the household can reduce the energy consumption of pumping. We examined the operation of a range of system components for rainwater supply, such as pumps, switches and pressure vessels, in a controlled residential environment (a model house) to understand their impact on the energy required for rainwater supply in urban dwellings. Results show that urban rainwater applications have flow and volume requirements which cause pumps to operate at high energy for rainwater delivery. Matching pump sizes to end use requirements and adoption of ancillary devices (pressure vessels and header tanks) have the potential to lower the energy footprint for rainwater supply. However, the energy savings can be constrained by dwelling characteristics, appliances and system design. © IWA Publishing 2013

How supply system design can reduce the energy footprint of rainwater supply in urban areas in Australia

In Australia rainwater tanks are used in cities to reduce demand of mains water and increase the resilience of cities to drought. Rainwater is collected in a tank and supplied to a dwelling through a small pump. Typically the energy footprint for rainwater supply (in kWh/kL) is higher than for centralised water supply, but it can also vary markedly from dwelling to dwelling. This study aimed to understand how the design of the rainwater supply system from the collection tank to the household can reduce the energy consumption of pumping. Therefore we examined the operation of a range of system components for rainwater supply, such as pumps, switches and pressure vessels, in a controlled residential environment (a model house) to understand their impact on the energy footprint for rainwater supply in urban dwellings. Results show the impact of end uses, pump size and switches on the effectiveness of pressure vessels in reducing the energy footprint for rainwater supply

Guidance for the use of recycled water by industry

This document aims to provide information on the key issues confronting the industrial water user in respect to the use of recycled water on a site. The information is both technical (corrosion processes, health issues etc.) and nontechnical (public perceptions, product acceptance etc.)

Condition inspection of rainwater tanks in Melbourne

© 2015, Engineers Australia. All rights reserved.The installation of rainwater tanks has increased to around 30% of homes in Melbourne largely from Government rebates over the Millennial Drought and introduction of 5-star home regulations in 2005. Rainwater tanks help to diversify a city's water supply and confer a range of environmental benefits, especially through reduction of stormwater runoff. However, the management of this infrastructure is left with home owners with little oversight from policy makers or water companies. As such, the longevity and efficacy of this investment over time is uncertain. Surveys of the physical condition of rainwater tanks will identify common faults and problems as well as quantify any deterioration over time. There has previously been no published large-scale study regarding the condition of rainwater tanks in Melbourne although a smaller study of limited scope has been reported for South East Queensland. This paper reports on the physical inspection of a sample of 417 sites with rainwater tank systems across Melbourne including the connected roof area, pumps and ancillary devices. The survey, undertaken in 2013 and 2014, shows that while some aspects are fairly non-problematic, such as those relating to the tank barrel, there are also some serious concerns. Too many foundations were found to be in a dangerous condition and faulty automatic switches and pumps contribute to a significant loss of water savings. There are also concerns about the water quality with more than half of all samples found to be either smelly and/or discoloured. The spread of arbovirus with mosquitoes breeding in tanks is another concern because many were found to contain mosquito larvae. The results have ramifications for Government and water company policies which are driving greater use of rainwater and highlight the need for improved management of these infrastructure assets

Repetition-free longest common subsequence

We study the following problem. Given two sequences x and y over a finite alphabet, find a repetition-free longest common subsequence of x and y. We show several algorithmic results, a computational complexity result, and we describe a preliminary experimental study based on the proposed algorithms. We also show that this problem is APX-hard

Australian examples of residential integrated water cycle planning: accepted current practice and a suggested alternative

Australian examples of Integrated Water Cycle Planning (IWCP) for residential development demonstrate that providing multiple household-water connections is a generally accepted practice. These connections typically include a potable mains supply, a separate non-potable supply utilising reclaimed water and/or a household roofwater tank for non-potable uses. Stormwater is not fully exploited as a potential urban water source. The advent of national guidelines for using recycled water for drinking purposes is expected to simplify IWCP towards a single-line household-water supply reclaimed from a range of different sources. An IWCP approach is suggested in this paper based on a single household supply complemented by: 1) potential separation of blackwater to reduce human health risk and to enhance community acceptance of recycled water, 2) the use of water sensitive urban design requirements of storing and slowly releasing urban stormwater, and 3) taking advantage of economies of scale by integrating communal roofwater tanks into the urban stormwater system

Using urban stormwater and aquifers or reservoirs for non-potable and potable supplies : key outcomes from the MARSUO research project

A project titled 'Managed Aquifer Recharge for Stormwater Use Options' (MARSUO) has investigated the public health, economic and public acceptance aspects of a number of different options for using stormwater via managed aquifer recharge and/or via reservoirs. This evaluated the quality of stormwater generated in the City of Salisbury, the treatment requirements and risk management measures necessary to assure safe water quality for public open space irrigation, third-pipe reticulation to homes and for potential drinking water supplies. The project also assessed biofilms and water quality impacts in distribution systems, public acceptance, and the economics and environmental impacts of options. An existing stormwater harvesting facility at Parafield in the City of Salisbury, South Australia, was chosen as the primary site for evaluation. Data from harvesting operations enabled assessment of their performance for non-potable uses and determination of additional treatments, preventive measures and costs of achieving drinking water standards. Studies of satellite sites in Australia, Singapore, China and India were undertaken to compare stormwater quality and treatment requirements for potable use and allow interpretation of the relevance of results from Salisbury. This paper provides an overview, with examples of results to give the Australian water industry a taste of the information now available for public use