Mr. Liam McCarton:

I will deal with the points raised in reverse order, starting with the last point on maintenance. We are particularly conscious of the constraints on local authorities, in particular that the parks departments are under pressure. The picture in our presentation was from Philadelphia and it took between ten and 15 years to get to that point. The core innovation was the partnership with community. Within the local authority structure in Philadelphia they created a number of catchment areas and each community were part of the design and maintenance theme for that. Deputy Murphy is correct that it requires a certain element of transfer of responsibility. This project shows one way of overcoming maintenance issues and is linked to the combined sewer. The Deputy questioned the nature of the surface water drainage system and she is correct that in Dublin, in particular, we have a number of combined sewers and we have a lot of sewers at the receiving of rivers. The consequences are felt increasingly with the effects of climate change.

In response to the Deputy's question, there are possibilities if we look at the concept of on-site treatment. In the cases of a number of catchments around Dublin, we could look at where the storm water is emanating from. I suggest that rather than treating it at the end of the system or discharging it into the Liffey, which is what happens to most of it at present, we should look at point source treatment. I can give the Deputy a simple answer without getting into a great deal of detail. There are possibilities in this regard.

The Deputy was quite right in what she said about the domestic rainwater harvesting system. A lack of innovation and high costs have been among the big barriers in this respect in Ireland - and in the UK, to a certain extent - in the cases of both new-builds and retrofits. We have undertaken a number of studies to look at how innovations can take place. Indeed, we have installed one or two systems in private houses. We are involved in a project at Carrowholly national school near Westport. We have some publications on that project. Storage accounts for approximately 50% of rainwater harvesting costs if it is properly designed. Storage is way over-designed at present, assuming these systems are being used to supply toilet demands only. A typical tank size in some of our studies would be 1 cu. m, which would be approximately the same size as an oil tank. By contrast, off-the-shelf systems use tanks that are 9 or 10 cu. m. There is a need for innovation in the system.