The perceived barriers to the inclusion of rainwater harvesting systems by UK house building companies

This work investigates the barriers that exist to deter the implementation of rainwater harvesting into new UK housing. A postal questionnaire was sent to a selection of large, medium and small house-builders distributed across the UK. Questions were asked concerning potential barriers to the inclusion of rainwater harvesting in homes separated into five sections; (1) institutional and regulatory gaps, (2) economic and financial constraints, (3) absence of incentives, (4) lack of information and technical knowledge, and (5) house-builder attitudes. The study concludes that although the knowledge of rainwater systems has increased these barriers are deterring house-builders from installing rainwater harvesting systems in new homes. It is further acknowledged that the implementation of rainwater harvesting will continue to be limited whilst these barriers remain and unless resolved, rainwater harvesting's potential to reduce the consumption of potable water in houses will continue to be limited

Influence of scale on graywater reuse systems,

Greywater re-use has much potential as a water conservation measure although its uptake has been tempered somewhat by concerns over the potential risk to health, financial viability and the absence of formal legislation. The focus of these concerns varies according to the planned scale of re-use. At the domestic scale, research has shown that although greywater re-use is technically feasible and conceptually attractive to a proportion of homeowners, presently, the financial returns from water savings are too small to encourage wider uptake. It has been suggested that the financial viability of greywater re-use improves with an increase in scale. This research reports on the performance of water re-use systems using a computer simulation model. Re-use system design is evaluated and re-use system performance predicted. The importance of estimating the water saving potential and water quality implications of a planned re-use project becomes more acute as the scale increases. In order to estimate water saving efficiency and evaluate system design, it is necessary to understand the patterns of water flow in a building. Yet, there is a limited availability of detailed appliance usage data for multi-occupancy building. The appliance usage of multi-occupancy residential buildings can be estimated from single-family water usage data. Results show that increases in storage size give improved re-use system performance up to a point, after which increases in capacity result in reduced gains in performance. For a single family household of 4 occupants this point is around 250 litres and for multi-occupancy buildings it is around 1000 litres for all occupancies. Disinfection performance in lower occupancy buildings is compromised if the storage capacity is increased beyond these values. Simulating different levels of component reliability and frequency of maintenance revealed that performance was significantly reduced if systems were maintained at 3 month or even 1 month intervals, although, weekly maintenance checks maintained performance levels even for frequently failing components

Small scale water recycling systems-risk assessment and modelling

Abstract This paper aims to use quantitative risk analysis, risk modelling and simulation modelling tools to assess the performance of a proprietary single house grey water recycling system. A preliminary Hazard and Operability study (HAZOP) identified the main hazards, both health related and economic, associated with installing the recycling system in a domestic environment. The health related consequences of system failure were associated with the presence of increased concentrations of micro-organisms at the point of use, due to failure of the disinfection system and/or the pump. The risk model was used to assess the increase in the probability of infection for a particular genus of micro-organism, Salmonella spp, during disinfection failure. The increase in the number of cases of infection above a base rate rose from 0.001% during normal operation, to 4% for a recycling system with no disinfection. The simulation model was used to examine the possible effects of pump failure. The model indicated that the anaerobic COD release rate in the system storage tank increases over time and dissolved oxygen decreases during this failure mode. These conditions are likely to result in odour problems