Policy 5.14 Water quality and wastewater infrastructure
A The Mayor will work in partnership with the boroughs, appropriate agencies within London and adjoining local planning authorities to:
a ensure that London has adequate and appropriate wastewater infrastructure to meet the requirements placed upon it by population growth and climate change
b protect and improve water quality having regard to the Thames River Basin Management Plan
B Development proposals must ensure that adequate wastewater infrastructure capacity is available in tandem with development. Proposals that would benefit water quality, the delivery of the policies in this Plan and of the Thames River Basin Management Plan should be supported while those with adverse impacts should be refused.
C Development proposals to upgrade London’s sewage (including sludge) treatment capacity should be supported provided they utilise best available techniques and energy capture.
D The development of the Thames Tideway Sewer Tunnels to address London’s combined sewer overflows should be supported in principle.
E Within LDFs boroughs should identify wastewater infrastructure requirements and relevant boroughs should in principle support the Thames Tideway Sewer Tunnels.
5.58 Most of London’s waterbodies fail to achieve ‘good’ ecological status/ potential as set out in the Thames River Basin Management Plan. This sets out the requirements of the Water Framework Directive. Sources of pollution include misconnections of sewerage to surface water drains, contaminated run-off and storm sewerage. Spatial planning measures helping to improve London’s waterbodies are reflected throughout this Plan (see in particular policies 2.18, 5.10, 5.13, 5.14, 5.15, 7.18 and 7.24). Effective wastewater infrastructure is fundamental to sustainable urban life and therefore investment and expansion are required. Currently, Thames Water is implementing plans for additional sewage treatment capacity at several major works, including additional capacity for the treatment of, and energy recovery from, sewage sludge. While the impacts of these works need to be minimised and mitigated, it is nevertheless essential that a positive planning approach is in place to support this investment.
5.59 In 2007, the Government approved construction of the Thames Tideway Sewer Tunnels in two phases (Lee Valley to Beckton and west London to Beckton). For the latter, Government notes that ‘need has been demonstrated’, and Thames Water was granted a Development Consent by the Secretary of State for the Thames Tideway Tunnel in September 2014. This will address the long-term problem of combined sewer overflows, which has resulted in the discharge of millions of tonnes of untreated sewage into the Thames each year.This is a strategic project for London. Opportunities to reduce the construction and operational impacts, the overall energy demand and the costs of the project should be taken. In addition, there are continuing programmes to deal with problems of sewer flooding in some areas of London; these need to be completed and where required, the lack of sewer capacity addressed.
 Defra: National Policy Statement on Waste Water (March 2012), p 17 -21