Jiang, J., Acheampong,B., He,Q., Balazs, T. and Bancroft, T., Faculty of Physics Science, University of Surrey, UK(free)
Greywater is defined as wastewater streams from baths, showers, basins, laundries and kitchens but not wastes from toilet flushing which has been termed as black water. In various studies, per capita consumption (PCC), as litres water per person per day, has been used to quantify the water consumption. The PCC in the UK in 2001 was 149 based on the UK OFWAT 2001report. In the same year the French average was 125. In the US, the water consumption is higher than most European countries, the PCC reaches 382 (Lazarova et al, 2003). Table 1 compares the breakdown of water consumption ratios in US, UK and Germany. Strong similarity can be observed within the shown values. It can be seen that water usage for toilet flushing is set out around 1/3 of all water consumption. Laundry operational water falls between 10 and 15% while bath/shower/basin consumptions reveal higher variation within 20 and 37%, yet it ought to be noted that `US data may contain extensive irrigational water usage in the “Other” section, hence the slightly lower values at every point. This small, farming practice is probably the cause of very high PCC value as well. By the data analysis as shown above and considering the regional differences it can be summarised that water used for toilet flushing is no more than 30% of total water consumption. Projecting this ratio onto the characteristic of generated wastewater, it can be stated that the amount of generated greywater is higher than blackwater. Thus it could be estimated that by toilet flushing alone, at least 30% of the total household water consumption might be saved by the grey water recycling activity.
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