Water water everywhere

At the end of last year, the Department of Environment, Food and Rural Affairs (DEFRA) announced that it intended to publish a Water White Paper by ‘early summer 2011’. Before its publication, DEFRA has called for views from as many people as possible, from industry experts to ordinary people on the street.

This White Paper will focus on the future challenges facing the water industry. In publishing this White Paper, the Government will look to address the key issues around water in the UK and how we might begin to tackle them.  The key issues can be summarised as escalating demand for water caused by increased population and standards of living (more water/energy intensive devices such as power showers and pressure washers) and increased pressure on ‘pinch points’ for supply exacerbated by climate change.  The heaviest average rainfalls are in the North of our island while the greatest proportion of the population lives in the South.  Climate change with its hotter, drier summers and warmer, wetter winters magnifies this natural imbalance.  We may well have enough water but it’s in the wrong place at the wrong time.

In England, the latest Water UK sustainability indicators for 2008/2009, showed that the average person uses 147.4 litres per day.  This is all from potable water that has been cleaned, treated and pumped from reservoirs, rivers or aquifers. Currently official figures indicate that 4,341,000,000 litres of water per day in 2008/2009 leaks out of pipes before it ever gets into homes and buildings. In the UK we have come to expect some of the highest quality water in the world, and an almost endless supply for drinking, preparing food, washing, watering our gardens, washing our cars, in many industrial processes and cleaning our clothes and teeth.  To ensure we have safe bathing water and good public health we have developed an infrastructure and regulatory framework that ensures both water and sewage are both treated to extremely high standards.

Much of the water we use in homes and buildings is disposed of using the pipe network that handles wastewater from toilets and it is then taken for treatment at a sewage works where it is treated by wastewater treatment processes that are very carbon intensive.  Extracting water from its source, taking it to a treatment works and then distributing it to homes, offices and factories all create carbon emissions (about 5M te CO2e per annum) but if rainwater were harvested or greywater re-used at these locations, then a huge dent could be made in this total.

We need to use water much more efficiently and sustainably if we are to continue to enjoy high standards and maintain a constant supply regardless of climate change. The South East and East of England have ever-increasing demands on a finite water supply. The drought of 2004-06 was only managed through controls on what we could use water for. Droughts and hosepipe bans are likely to be more common going forward. It is worth noting that on 7 July 2010 United Utilities introduced the first hosepipe ban in North West England for 14 years.  With climate change it is unlikely to be as long again before the next one.  By 2080, some long term climate projections forecast half as much rainfall in the summer (nothing like fully offset by 30 per cent more rainfall in winter) in the South East. We need to plan ahead and each of us needs to play our part. We also need to cope better with regular flooding caused by heavy rainfall and thunderstorms, mainly over a short period.

What is being done?
Like others, the regulated water companies in England and Wales (21 in all) are all subject to the Carbon Reduction Commitment (CRC).  Currently their total Greenhouse Gas (GHG) emissions (5.07 MteCO2e in 2008/09) amount to about 1.1 percent of the UK total between them.

These companies are committed to a voluntary target of 20 percent of their energy to be from renewable sources by 2020. In 2008/09 water companies generated 742 GWh of renewable energy themselves – approximately 8.5 percent of their total operational energy consumption for that period.  A significant income stream is possible for those companies responsible for sewerage, from Renewable Obligation Certificates (ROCs) and the new Feed-in Tariffs (FiTs) which started on 1 April 2010. Both commercial and domestic buildings can take advantage of the opportunities FiTs offer.

To help water companies, (and indeed this would be applicable to companies in other sectors such as commercial building developers) investigating the possibility of using assets for the application of renewable energy schemes using generation techniques such as wind turbines and photovoltaic (PV) cells, ADAS has developed a sophisticated GIS based tool that provides an assessment of the suitability of deploying generating capacity at a given location. The screening tool incorporates data on the proximity of residential property, wind and solar resource, grid connection and environmental designations. This desk-based assessment delivers a low-cost method of identifying the sites that are the most appropriate for deployable renewable energy generating capacity before more detailed feasibility studies are carried out that may indicate that the site is not viable.

As well as increasing the generation of renewable energy to treat and transport water, we need to address consumption.  All water users in the UK, from commercial to domestic building designers, farmers to industrial plants are starting to think about the most effective ways to manage water usage. This is the right thing to do both economically and energy-wise, to save the planet for future generations.  Some of the key ways to do this are:

- Rain water harvesting: Rainwater harvesting is the capturing and storing of rainwater.  It can be used to provide water for non-potable uses such as livestock, water for irrigation or cold water services such as toilet flushing.  Rainwater collected from the roofs of houses, offices and agricultural buildings can make an important contribution to reducing the volume of potable water required.

- Increased use of ‘Greywater’:  Greywater is wastewater generated from activities such as laundry, dishwashing, and bathing, which can be recycled on-site for uses such as landscape irrigation and constructed wetlands. Greywater differs from the waste water generated from toilets which is designated sewage or “black water” to indicate it contains human waste. The simplest way to use greywater is to divert the water directly to adjacent parks and gardens.

Regulations change by country and region, but common guidelines for safe usage include not storing the greywater for more than 24 hours, ensuring it cannot pool or run off, and depositing it with subsurface irrigation rather than spraying it and creating aerosols. Greywater diversion systems can be both designed in new homes and buildings, or implemented and retrofitted to many existing structures.

Water diversion systems tend to be highly efficient, effective and safe for simple applications where potable water is not required. Fully engineered systems incorporate a sump pump and surge tanks and deliver the water through sub-surface irrigation. Greywater from the shower or bath is generally good quality water for the garden. The soap levels at the dilutions typical are actually good for the garden as they are a wetting agent. When laundry greywater is diverted to the garden, the laundry products used must be chosen carefully to ensure phosphate and salt levels are low, and that pH balance is neutral.  Basic guidelines are also available from system suppliers. It is essential that greywater is diverted to sewer when garden-unfriendly products are being used.