UK Report Looks at Carbon Embedded in Water, Potential Savings Large

A new report released yesterday in the UK by the Environment Agency and the Energy Saving Trust explores the energy and carbon embedded in residential water use. Titled Quantifying the Energy and Carbon Effects of Water Saving, the report concludes, among other things that 6% of the UK's carbon emissions are related to water and that Britons could save 30% of the carbon emissions from heating water through some simple retrofits.

I had a chance to browse the report and it is loaded with good information, however, I was unable to specifically find a reference to the 30% reduction in carbon emissions. That figure comes from an article written by the Guardian Newspaper called Saving water could cut water-heating emissions by 30%, report finds, which explains:

Britons could save 30% of the carbon emissions associated with heating water at home by following simple advice such as lagging pipes and using low-flow taps, according to energy experts.

They estimate that installing just a few water-saving measures could save a typical household £225 per year on combined water and energy bills.
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"If the drive toward zero-carbon homes goes as planned, by the time you get to a really energy-efficient home, the energy required for space heating is going to be quite small, but unless you do something about water use, that's going to dominate and will account for over 70% of carbon emissions," said Magda Styles, water and waste strategy manager at the EST.

But she said very simple methods of water and energy efficiency could take out 5% of the emissions associated with water, equivalent to taking 600,000 cars off the road.
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The EST report suggests taking showers instead of baths, retro-fitting showers and taps with low-flow heads, lagging hot water pipes, washing dishes in a bowl rather than under a running hot tap and installing a water meter. "It's been documented quite well that metering reduces water consumption by up to 15%," she said. "We're not trying to make people endure hardship and do away with hot water. In most cases, it's a simple prevention of waste."

According to the report, changing a 16 litre per minute shower head with a six litre per minute head, and using a 4.5 litre toilet instead of nine litre one, could result in annual savings of 67m3 of water, 371kg CO2 and £225 for an average household.

Getting beyond 30% reductions in CO2 for individual households would be possible, said Styles, by additionally replacing old washing machines and dishwashers with more energy and water-efficient models and more conscious behaviour change that minimised use and heating of water.

There seems to be conflicting statements in the Guardian article but I think it is trying to say that the carbon emissions for heating water can be reduced by 30%, while overall water-related carbon emissions--including the upstream emissions required to pump and treat drinking water and the downstream emissions resulting from wastewater treatment--could be reduced by 5%.

I think this is a low-ball estimate and skimming through the report I couldn't find these specific numbers. If you think about it, the report found that nearly 90% of the carbon embedded in water comes from water heating. If that can be reduced by 30% then wouldn't we be talking about a total carbon reduction of about 27%? I would be curious how these statements are reconciled and will try to dig through the entire report to see if I can find some clarification.

Regardless of the confusion in the Guardian article, this report is definitely worth a look. It comes in two versions which you can access below:

Quantifying the Energy and Carbon Effects of Saving Water SUMMARY REPORT

Quantifying the Energy and Carbon Effects of Saving Water