A new report from the London Assembly Environment Committee is warning that Londoners are facing drinking water shortfalls, with demand is outstripping supply in the capital, while sewer overflows and flood risk are increasing as intense rainfall becomes more frequent.

The Committee’s investigation has focused on four key challenges in the report ‘Growing, growing, gone: Long-term sustainable growth for London’ :

• water shortfalls and how to deal with excess water;
• pressures on the natural environment and maximising use of green spaces and waterways;
• energy needs and keeping carbon emission down and:
• putting the circular economy at the heart of London’s economic development.

On water, the report found London’s demand for water could outstrip its supply by 20 per cent by 2040 – without action, Thames Water projects a shortfall of 41 million litres per day.

Rollout of SuDS has fundamental role to play

The Committee is calling for an integrated water strategy for London and believes that the roll out of sustainable drainage systems (SuDS) and rainwater capture has a fundamental role to play. However, the report says implementing such a strategy is difficult as water management is fragmented across many different bodies. The Committee is now calling for regulatory changes to facilitate integrated, sustainable and long-term focused water strategy.

Introducing the report , the Committee said:

“Past fragmented approaches are reaching their limits and the development of a long-term sustainable water strategy across supply, demand, drainage and flood risk needs to be embedded in statutory Mayoral strategies, including the London Plan, the Transport Strategy as well as the Environment Strategy. But even this may not be enough and the Mayor will need to debate options for a potential new major water source.”

Attempts to deal with each problem separately are running into difficulties, according to the report – however,  new approaches which tackle them together promise to be much more effective.

Commenting on water management, the report says that Thames Water’s current projected headroom 20 per cent shortfall of baseline water supply against demand by 2040, if anything, understates the severity of the situation.

Rapid floods could lead to loss of life and billions of pounds of property damage

On flood risk and drainage, the report says London’s greatest flood risk, taking into account existing protections such as the Thames Barrier and other river and estuary defences, is of surface water and sewer flooding in the event of a heavy rainstorm, warning:

“If London were to experience an extreme rainstorm (such as those that have affected parts of the country in most years this century), rapid flooding would ensue, with likely loss of life and property damage in the order of tens of billions of pounds.”

The Report welcomes work pursued by the Mayor to reduce London’s flood risk, especially by mapping the risk of surface water flooding in the event of heavy rain, and by promoting the use of sustainable drainage systems (SuDS) and permeable surfaces.

The Mayor has also recently published a draft Sustainable Drainage Action Plan which envisages reducing flows to London’s drains by one per cent each year for the next 25 years. However, the Committee says this target needs defining, will need monitoring, and that it is not clear how it will be delivered.

“There is a great need to fit SuDS to both new and existing properties, the road network and to exchange impermeable paving for permeable wherever possible, and to ensure that properties in flood risk areas are resilient to the flooding that they are unfortunately likely to experience sooner or later. The suggestion in the draft Sustainable Drainage Action Plan that the drainage element of business water bills could be related to the impermeable surface of the premises could provide an incentive to fit SuDS and should be explored further.”

On an overall water strategy, the Committee says this works best on an integrated approach and that London’s key challenge is to bring work on these areas (and related non-water issues such as road maintenance) together.

Next Mayor must take action on key issues

However, a number of institutional barriers stand in the way, according to the report: the Mayor has an integrated Water Strategy, but this does not itself have statutory force and other bodies are responsible for delivering most areas of water management.

Thames Water and London’s other water supply companies have many of the relevant powers, but Ofwat and the water industry regulatory framework stipulate separate plans for drainage and for water resources. Flood risk responsibility is split, largely between the Environment Agency and local authorities. Bodies such as TfL and highways departments that manage the streetscape are not primarily responsible for drainage; neither are they for supplying water needs. 

The Committee is calling for the next Mayor to take action on a number of key issues, including:

• Further develop and build on work with water management bodies to secure greater integration of water strategy across supply, demand, drainage and flood risk.
• Embed sustainable integrated water management strongly in statutory Mayoral strategies, including the London Plan and the Transport Strategy as well as a new Environment Strategy
• Use Mayoral funding streams, including housing, transport and retrofit programmes, to support water strategy where appropriate
• Require integrated water management plans for major new development areas

The Committee also wants the next mayor to lobby Ofwat and government for the necessary regulatory changes to permit integrated, sustainable and long-term-focused water strategy. This  could include aligning or integrating drainage plans with water resource management plans, and ensuring that longer-term strategy is drawn up before shorter-term business plans, the report says.

Click here to download Growing, growing, gone: Long-term sustainable growth for London

Waterbriefing is media partner with the Institution of Civil Engineers keynote Flooding and Water Management Conference 2016 taking place in London on Thursday 30th June. Click here  for more information about the conference.