Water is a finite resource. The UK concrete sector is very aware of the importance of water, especially when considered alongside the likely impacts of global warming and climate change.
Water is essential to the hydration of cement, which enables it to act as the main binder for concrete. Water management is also an essential part of responsible concrete manufacture, with industry guidance in place for best practice. It is recognised by specifiers and the concrete industry alike that water needs to be treated as a valuable resource.
The concrete industry and its constituent material sectors committed to the MPA Water Strategy in 2017. It is based around three main principles:
- Minimising water consumption
- Prioritising use of the most sustainable water sources available
- Protecting the environment through good water stewardship.
Water extraction is an important aspect of responsible sourcing certification to BES 6001. To achieve a primary level of performance the organisation must establish a policy and metrics for water extraction in terms of reducing mains water use and the efficient and effective use of ‘controlled groundwater’. Controlled groundwater is defined as all water abstracted from boreholes and other surface water features which need an abstraction license known as a ‘Full License’ in the Water Act 2003. To achieve a higher performance rating in BES 6001 the organisation must demonstrate external verification of the reported data on water extraction.
Embedded water refers to the amount of water required to produce a product from start to finish. Embedded water is most commonly used with reference to agricultural products but may be applied to non-agricultural goods as well, such as construction products. All construction products have embedded water in them and the UK concrete sector is doing all it can to minimise its impact on this resource.
A 2004 study (1) in Australia estimated that a typical Australian house represents about 15 years worth of operational water, 15 years of water for cooking, cleaning, washing, drinking, toilet flushing and gardening all embedded within a single home. This study estimated that a kilo of concrete has about two litres of embedded water, a kilo of timber about 20 litres, a kilo of steel about 40 litres, a kilo of aluminium about 88 litres, and that a kilo of plastic has about 185 litres of embedded water.
Concrete’s cradle-to-gate water consumption can be found using the ‘net freshwater’ category as defined in Environmental Product Declarations (EPDs), this is often less than comparative building materials, however any comprehensive comparison should be done at a building level.
The performance indicator for water, reports that in 2008, the base year of data collection, the value was 86 litres/tonne (including water used in the supply of raw materials). In 2017, mains water consumption had reduced by 18% to 70 litres/tonne.