I am grateful for the opportunity to respond to the observations made by the Government relating to the evidence I provided to the House of Lords Science and Technology Committee inquiry on Water Management. On a topic as fundamentally serious as the provision of potable water under conditions of uncertainty it is important to have debates that clarify issues and identify uncertainty.

The clarifications in the Government response are helpful and reinforce the fundamental point that I was making, namely that targets, ambitions above the target and the use of the same value as an annual housing increase as the gross addition over a decade or more as part of "ambitions", only serve to obfuscate.

I note that the majority of the observations I made in the original material have not been addressed and I assume that these are valid and will be noted and perhaps incorporated in future analysis.

I note that in the response an additional 2.8 million dwellings (by 2016) is calculated to generate a water demand of only 728 million litres per day. Thus average household demand in these new dwellings will be 260 litres per household per day. These are figures for the whole of England so I assume that a household size declining from 2.4 to 2.1 over the period is reasonable (the household size predictions relate to 2021) suggesting a per capita demand of 108 to 123 litres per person per day. At face value this suggests a substantial efficiency gain compared to current per capita water demand nationally of about 160 litres per person per day and rather above that figure for the SEERA region.

It is interesting to note that the original analysis cited in the response appears to be predicated on an assumption that there is actually no net increase in population through the additional housing "ambitions". Instead, all of these families will simply be dividing to occupy this new housing. It would be interesting to be aware of the basis of such an assumption and the extent to which it also applies to the housing targets. Again I have to point out that the simple resizing of households by this mechanism will have a significant impact on water demand.

I have found little in the Government's response that persuades me to change the overall thrust of my analysis as submitted to the Lords Science and Technology Committee. However I welcome wholeheartedly the clarifications provided and the opening of a debate into the future of water requirements for the UK and for the south east of England in particular.

Professor Adrian McDonald

16 October 2006