The Mayor's draft water strategy - london.gov.uk - Greater London ...

86 The Mayor’s draft water strategy
the prolonged drought in the south and east
of England in 2005 and 2006 has highlighted
customer concern at high leakage levels at a
time when they were subject to restrictions
on their water use. Thames Water’s willingness
to pay studies suggests that consumers
believe current leakage levels in London to
be unacceptable and are prepared to accept
these higher costs.
6.16 Since then, a further review of this
approach to leakage target setting has been
undertaken by Ofwat and the Environment
Agency 95 which seeks to take into account
a wider range of costs and benefits.
However, none of this work takes account
of the particular conditions that prevail
in London. As noted in paragraph 3.5, for
example, no account is taken of the serious
damage caused to other infrastructure such
as the London Underground network by
leaks and burst mains 96 , and there is little
information on the costs to business 97 . Burst
mains and leakage repair causes serious
traffic congestion. Whilst mains renewal
in a busy street such as Tottenham Court
Road disrupts traffic in the short term, once
completed it should avoid problems for
decades. However, Thames Water’s view is
that beyond 2020 further leakage reduction
will become an increasingly expensive way
of balancing supply and demand because
the leakage reduction per kilometre of mains
replaced will be diminishing, given that the
mains with the worst leakage will largely
have been replaced 98 . Even so, the company
still expects to have the highest rate of
burst mains in England and Wales due to the
number of old cast iron mains that will still
be in-situ 99 .
6.17 Information provided in the Statement
of Response: Draft Water Resource
Management Plan indicates that the
overall rate of leakage will be reduced from
217 litres per property to day (l/p/d) in
2007/08 to 123 l/p/d in 2020-2025 and
then to 114 in 2030- 2035 100 . The Mayor
does not regard this as a satisfactory
objective after some 30 years of Victorian
Mains Replacement, Active Leakage Control
and customer supply pipe leakage reduction.
The water companies should be working
towards a target of 80 l/p/d across the
London Water Resource Zones by 2035.
This may not be economically justifiable
at present (see paragraph 3.11) but the
25-year time scale of Water Resources
Management Plan should allow for
significant improvements to be achieved in
the cost-effectiveness of leak reductions and
mains renewal. Londoners could reasonably
expect that once current street works are
completed, London will have a water supply
system that meets a good, if still not the
very best, international standard.
Thames Tideway tunnel and treatment
6.18 The various proposals for tackling the
problems caused by London’s combined
sewer overflows (CSOs) are discussed above
in paragraphs 5.3 to 5.11). The capital cost
of the work to be completed in the next
price review period, between 2010 and
2015, is £963 million 101 . This will see the
completion of the Lee Tunnel in 2014, and