Flooding is partly a natural, partly a man-made phenomenon. It impacts on many water company activities and can have serious implications for water and wastewater services. The key role for the water industry is in planning for and minimising the risks.
Droughts and floods are two sides of the same coin: too much or too little water, in the wrong place, at the wrong time. But while droughts mainly affect water supply, flooding impacts both water supply and wastewater services.
For historical and economic reasons the UK has mostly combined sewer systems in urban areas to collect both foul sewage and surface water. When combined sewers cannot cope with heavy rainfall, the result can be surface flooding or 'backing up' of foul sewers.
The frequency of such events is predicted to increase with climate change so the design of sewerage systems and flood risk management projects must be kept under review.
The key priority for water and sewerage companies is the prevention of internal property flooding and the reduction of surface flooding when the sewer system is overwhelmed. In the current investment period, 2005-2010, the industry will spend more than £1 billion in reducing the risk of sewer flooding.
Water companies have limited control over what is put into the sewer system. More control is needed of items and substances like fats, oils and grease that contribute to blockages. Campaigns such as Bag It and Bin It seek to increase awareness of the conseqences of inappropriate flushing.
Increased urban development has also increased the pressure on sewerage systems. Early consultation and consideration of the impact of development on water services within the planning system is therefore vital.
What is needed is a clear designation of responsibilities and duties in this complex area and a greater emphasis on more sustainable or 'softer' approaches, including catchment solutions and integrated or sustainable urban drainage systems.
Water companies can also be victims of flooding events and storm surges. These can take out or impair asset performance and can have serious effects on customers.