Summary: Dr Donata Dubber and Dr Laurence Gill - Water saving technologies to reduce water consumption and wastewater production in Irish households
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Typical on-site wastewater treatment systems for single houses in rural areas with no mains drainage consist of septic tanks and/or package treatment plants followed by a percolation area (soil attenuation system). If the subsoil permeability is not sufficient to take the effluent load, surface ponding may occur with associated health risks and a risk of runoff of pollutants to surface water.
Thus, a lower limit was defined for the subsoil permeability up to which the discharge to ground is permitted (T-value = 90 (EPA, 2009)). At lower subsoil permeability water will not be able to percolate into the ground at typical hydraulic
However, the reduction of water consumption by water saving devices such as low flush toilets, low-flow shower heads and low-flow taps will reduce wastewater production and hence hydraulic loadings on percolation areas. This could improve the functioning of the soil attenuation system (i.e. minimise surface ponding and runoff) and should be investigated for sites with subsoils of limited permeability. Technologies based on the principles of ecosanitation,
whereby the organics and nutrients from wastewater are recycled via composting toilets and urine separation, could also be a potential solution for the wastewater disposal problem in such areas but will require acceptance and high dedication from the home owners. However, the implementation of some of these principles can help to reduce the daily water consumption/wastewater production that needs to be treated and disposed of.