I have read the Environment Agency report and studies since have proven that the analysis did not take into account low energy systems on the market and use of rainwater harvesting in commercial situations. Energy is needed to run a rainwater harvesting system but the amount is so minimal in comparison to increasing water infrastructure, new reservoirs, new mains supplies. Lets not forget that we cannot live without water and surely a small amount of energy is a little price to pay for the larger water crisis at hand. The NHBC is more concerned about raising the cost of building homes than the environment and whilst new homes are built to the CSH standard, peoples water usage habits do not reflect what goes down on paper for planning. Rainwater Harvesting is the way forward.
 

It seems so short-sighted to criticize home greywater systems because their total carbon footprint might be higher than using municipal water! An efficient system can save thousands of gallons of drinking water per year with very low energy use - and while the "energy per gallon consumed" might be more than from a utility, one must also add the value of reducing the "water footprint" of the property - then net environmental effect is certain to be less. Visit http://www.wahaso.com for more information.
 

Small water treatment systems are relatively new and the development of treatment technologies is advancing very quickly. Some systems now are capable of generating their own energy to process grey and black water or sewage into potable or drinking water. Methane fuel cells (and plenty of that can be made treating sewage) will become common in the next yaer or so. The same cells are producing drinking water from sea water using new and advanced techniques a little different to desalination as we use widely today. In many of these new techniques energy efficiency is paramount.
 

First of all the article is very biased. The article must be read in the context that house builders represented by NHBC are generally not interested in installing new technology into their houses. For them it just complicates building and therefore reduces margins. Due to house builders traditional approach, we are behind most our European colleagues especially Germany and Skandinavia and regarding the discussed technology even Belgium, France and Spain. New technolgy should be embrassed.
Secondly the increased carbon used has to be put into perspective. We are in a drought meaning that the current mains water supply system is struggling to cope with demand. What does it help save carbon, if we care running out of mains water and not considering using alterntaives such as rain- or greywater?
Why are these systems common on the Continent? Germany installs roughly 80,000 systems a year (UK ~5,000). In Belgium rainwater harevsting systems are even mandatory.
An article by Celia Way from the University in Bristol states that in a 30 year life span of a rainwater harvesting system, it uses as much carbon as a flight of 3.5h; a 2,000mile journey with a car would use.... Or you would saveng via double glazing in a year.
Thirdly rainwater and greywater technology has move on since the study. There are systems on the market e.g. Eco-Compac that use a third of the energy used to pump mains water to your door step. These systems could be considered water and energy efficient.
Water saving fittings are the first step but in order to save more water rainwater harvetsing and greywater recylcing are the next steps.