Supply Support Sewage

Our five-year plan

This website summarises the main contents of our plan for the period 2015-20. It reflects the �final determination� published by our financial regulator, Ofwat, in December 2014.

The plan sets out the investment we intend to make to maintain and improve essential water and wastewater services, and achieve the targets agreed with Ofwat.

Our proposals are based on the challenges we face, our long-term promises and, most importantly, what you�ve told us.

The plan outlined below represents our current best estimate of how we intend to meet our targets. The details may change if we find more efficient and/or effective ways to do this.

Look out for:

  • The 'You Said' icon, featuring quotes from our customers that helped to inform our plan.
  • The 'Commitments' icon, letting you know our long-term commitments.
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Fixing pipes

We will improve 881km of water mains and reduce leaks

Water is an increasingly precious resource - so it's important that we find and fix leaks, as well as repairing or renewing ageing mains.

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Saving 59 million litres of water each day

We will provide safe and reliable water.

Fixing leaks quickly and efficiently is vitally important.

Reliable supplies

We will improve treatment works and equipment so that homes and businesses in our region continue to have the water they need

We will upgrade five of our London treatment works, which together supply 6 million people, and address population growth by providing new mains and pumps in 11 separate projects across our area.

It's our job to plan not just for the next five years but also for the long-term future. We will lead discussions to agree on the best option for the new source of water we believe will be needed by the late 2020s.

Water is a basic commodity we all need, so it has to be top quality, safe and clean.

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Smart meters 900,000 households will be fitted with new meters

New 'smart' meters help to locate leaks and encourage customers to save water

We will be able to read the meters electronically, with less need to visit them. We have already begun fitting these new meters and will accelerate our work across London, moving to other areas after 2020.

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I am on a water meter and it does make you think more carefully about how you use water.

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Better service

We're dedicated to providing better customer service

We will improve the service we provide through a variety of changes. Customers have told us they want us to get things right first time, resolve problems quickly and provide communication channels that suit them - so our plan focuses on improving these.

We will show customers we are easy to do business with and care, and that they can trust us.

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Great customer service never goes unnoticed. Friendly and helpful behaviour go a long way.

Helping you pay

We know that some customers struggle to pay their bill, and we will look at ways to keep costs down while maintaining the assistance we currently provide. This now includes a newly launched social tariff, which will halve the bills for those least able to pay, and benefit checks to help ensure people get the payments they are entitled to.

We will provide the services customers need in the most economic and efficient way.

We anticipate halving the bills of 37,000 households through our social tariff.

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Affordable bills are very important.

We will provide customers with a choice of easy-to-use contact options.


No one should suffer the threat of sewage flooding their home. We will improve the sewer system, reducing the risk for 2,127 properties.

Our plans include major flood relief work in west London, 14 investigations aimed at preventing rain infiltrating our sewers, and doing more to prevent blockages.

We'll also promote sustainable drainage, which encourages rain to soak away naturally or slows its progress into our sewers.

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Flooding can be devastating for families, so it's very important to ensure that our wastewater pipes work efficiently.


We'll be working hard to ensure sewage works and pumping stations cope with the demands of a growing population.

Among our proposals, we will carry out a major overhaul to update Deephams sewage works in north London and start work to refit two incinerators which burn sewage sludge to generate renewable energy. We will keep pace with population growth at 18 sewage works and increase sewer capacity to cater for housing developments.

Maintenance is an essential part of providing a good quality service.


We will generate 33% of our own power needs from renewable sources.

The environment is a vital part of our business: we source much of our water from rivers, to which we eventually return it following sewage treatment. We aim to increase the amount of power we generate from this treatment process, reduce what we take from watercourses and make a range of changes to help protect wildlife and plants. And by 2020 we'll educate 20,000 pupils per year about the environment and what we do.

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We will limit our impact on the environment and achieve a socially responsible, sustainable business.

I think generating renewable energy from sewage is a good idea to protect the environment.

Tideway Tunnel

We will provide a safe and reliable wastewater service.

The Thames Tideway Tunnel is necessary to cope with the increasing demand for sewage disposal in the future.

London has outgrown its sewer system

The Thames Tideway Tunnel is an essential upgrade, which is needed because the capital has outgrown its sewer system. The original network, built by the Victorians, is still in good condition but often fills to capacity when it rains, causing sewage to overflow into the nation's most iconic river.

The solution and its benefits

The tunnel will run for 15 miles under the tidal Thames. It will capture most of the pollution that would otherwise enter the river and transfer it to Beckton sewage treatment works, in east London. This will improve water quality in the Thames, significantly benefiting the environment and river users. The tunnel will help enable London's sewer system to cope with the demands of the 21st and 22nd centuries.

Future-proofing for 100 years

This solution will tackle the problem of sewer overflows for at least the next 100 years, and enable the UK to meet European environmental standards. It's a huge project that forms part of the Government's National Infrastructure Project and has to be delivered.

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Future bills

Our charges between now and April 2020 have been approved by our independent financial regulator, Ofwat. Throughout this period, the average household bill for water and wastewater services will remain below the industry average.

The agreed charges vary from year to year to reflect the costs of work we are planning to carry out in that period, and to spread the impact on bills of new assets, such as pipes and treatment technology.

Average bills across the five years will rise by about �12 (3.4 per cent) by 2020, excluding inflation.


Our performance targets

We have agreed with Ofwat a range of five-year targets. Our performance against some of these targets could affect average household bills in 2020-25.

For illustrative purposes, we have shown four of the measures below. In each case, you can choose between six performance levels to see the potential impact on an average bill, spread across the five years.

Water supply interruptions

Target is average of 7 minutes 48 seconds per property.


Target is 8.9% reduction from starting point of 665 million litres per day.

Internal sewer flooding

Target is 10.3% reduction from starting point of 1,029 cases.


Target is 0% reduction from starting point of 340 incidents.

Fixing pipes

Leaks are wasteful and undermine our message about how important it is to conserve water. It's vital we repair them quickly, as well as finding and fixing those below the surface.

By 2020 we aim to reduce the level of leakage by 59 million litres per day - enough to supply over 350,000 people. The new 'smart' water meters we install will play an important part, by helping show where water is escaping from our pipes, and those belonging to customers.

We also want to minimise the risk of burst pipes, which waste water, cut off supplies and cause huge disruption. We will fit monitors to our biggest water mains to reduce the risk of bursts happening.

Our plans include repairing or renewing 881km of water mains, plus a further 45km of our biggest mains in places where bursts would have most impact.

Reliable supplies

We must plan ahead to make sure homes and businesses have the supplies they need, despite the challenges of climate change and a growing population.

For example, we will upgrade five London water treatment works, which together supply 6 million people. This will ensure they can continue to reliably produce top-quality tap water. New mains and pump improvements are needed to keep pace with our area's growing population.

We have agreed with Essex & Suffolk Water to reduce the amount of water we transfer to their area until 2030, providing an extra 17 million litres per day.

We will encourage people to use water wisely - for example, by continuing to provide free water-saving devices. We also plan to save an additional 15.45 million litres per day by 2020, by giving advice and devices to newly-metered customers. And we will trial new price bands, which aim to encourage heavy water users to use less.

Despite these measures, we believe that by the late 2020s a major new water source will be needed - not just for our region, but the wider South-East. We will lead discussions with stakeholders, regulators and other companies to agree the best of a range of options.

Smart meters

We want to ensure there's always enough water to go round. But population growth and climate change will make that more difficult in the future.

Part of the answer is fitting more water meters. Our aim is that every building in our region will have one by 2030. This will encourage households to use less and will help them control their bills.

The meters we install will be 'smart' models that we can read electronically, helping households to monitor how much they use. They will also record how much water is flowing through the pipes, which will help us locate leaks from our pipes and those belonging to customers.

We have already begun to fit more meters. We will accelerate our work, installing more than 900,000, which will increase the proportion of metered homes in our region from 31 per cent to 56 per cent by 2020.

We'll initially focus on the London area, moving to other parts of our region after 2020.

Better service

We need to make improvements so that we consistently provide a high level of customer service.

We have already begun opening our revenue and billing contact centre for an extra five hours on Saturdays, and have reduced to two days the time allowed to answer emails.

In addition, we will:

  • Improve customer satisfaction from 4.3 to 4.65 out of 5 by 2020
  • Resolve 95 per cent of written complaints without the need for them to be escalated - a five per cent improvement
  • Offer to ring back callers waiting in a queue, at a specified time
  • Increase the proportion of bills based on actual meter readings, rather than estimates, from 85 to 96 per cent

We anticipate replacing our ageing billing system in 2017/18, helping us provide self-service online account management. In the meantime, we will investigate providing this using our existing technology.

We also plan to introduce a web chat service in the same year, so that staff can help customers who are making an online enquiry.

We'll continue to provide a choice of contact options. And our plans include a renewed emphasis on training and development, so that staff improve the way they handle enquiries.

Helping you pay

It's important that we keep bills affordable. So our plan mainly focuses on doing the minimum to maintain current standards, without storing up problems for the future.

We'll promote innovation, to find ways to provide the same service at a lower cost. And we will replace the systems we use to target people who choose not to pay, to help ease the burden on other customers' bills.

Even so, we know some households may struggle to pay their bill. We've already introduced a social tariff, which we forecast will halve the bills of those customers least able to pay. We forecast this will be helping 37,000 households by 2020.

We have also brought in benefit checks, to help ensure customers get payments they are entitled to. By 2020, we expect 25,000 people will have taken this up.

We will carry on promoting these, to increase the take-up and help more households, and are also donating a one-off tax refund of £10m into our Customer Assistance Fund between now and 2018.

In addition, we will promote ways of saving water to newly-metered customers, to help them budget for their household bills.


Sewage flooding the inside of your home is a horrible experience. We will protect 2,127 properties over the next five years. Our largest project will benefit homes in the west London boroughs of Hammersmith & Fulham and Kensington & Chelsea.

We will ensure that new developments don't increase the risk of flooding for existing houses, by promoting the use of sustainable drainage. This encourages rainfall to soak away naturally - for example, through permeable paving - instead of reducing capacity in our sewers. Working with local councils and developers, we aim to cover the equivalent of 28 football pitches with this type of drainage.

In some areas, heavy rain can soak through the soil into our sewers. We'll investigate how to prevent this at 14 locations across our region. This will benefit 328 households who sometimes can't flush their toilets for weeks on end when the ground is waterlogged.

And we'll guard against flooding at 24 of our sewage works by installing protective measures. Blocked sewers can cause flooding too. So we'll increase our warnings to households not to put materials like fat and cooking oil down the drain. We will target the worst-affected areas, promoting the message 'bin it, don't block it'.


We must make certain we can continue to transport sewage from our 5,000-square-mile region and treat it to the required standard.

Our plans include major improvements to Deephams sewage works in north London, parts of which date from the 1950s. This will ensure we meet new treatment standards to be introduced in March 2017. We'll also reduce the risk of odours for 6,600 homes near our sewage works.

We run two incinerators in east London, which burn sewage sludge to generate renewable energy. They have been in use since 1998 and now require a major refit, which we will continue beyond 2020.

Eighteen of our sewage works need improvements to keep pace with an increasing population locally. We will set aside funding for smaller works, in areas where growth is less certain. In addition, we expect to increase sewer capacity to serve new developments in parts of our region.

In October 2016 we will take responsibility for 4,500 privately-owned pumping stations, on top of the 2,600 we already run. We will ensure those we know about are of a safe and serviceable standard while we assess their condition further.


We aim to protect the environment and reduce our impact on it. For example, we will reduce the amount of phosphorus, ammonia and other pollutants in the treated effluent we discharge to rivers, which will benefit plants and wildlife.

We will reduce how much water we take from rivers with insufficient flow by 22 million litres per day, and will set aside dedicated areas for wildlife at some of our larger reservoirs.

We will also increase the amount of renewable energy we generate - for example, from the sewage treatment process - sourcing 33 per cent of our power needs in this way. A new 'thermal hydrolysis' plant at Basingstoke sewage works will help achieve this and allow us to cease lime treatment, which is smelly and creates no power. We will also install more efficient generating equipment at 12 other works.

In addition, we will work with farmers to reduce fertilizer run-off into local rivers, which can damage the environment and increase water treatment costs.

Looking to the future, we will promote the environment through visits to our sites. We will open three new education centres, in addition to the five we are currently running, and will take on more staff to run them. By 2020, we aim to be educating 20,000 schoolchildren per year about the environment and what we do.

Tideway Tunnel

The backbone of London's sewer system was built in the mid-19th century. Although still in good working order, it was built to serve just two million people - far below the city's current population of eight million.

Coupled with an increase in building developments and paved surfaces, this means the problem of overflows to the River Thames is getting worse and worse.

When first constructed, the sewers were designed to overflow once or twice a year, but discharges now occur on average once a week, after as little as two millimetres of rain. As a result, tens of millions of tonnes of untreated sewage enter the river every year. It can stay in the river for up to three months before the ebb and flow of the tide finally takes it out to sea.

The Thames Tideway Tunnel will capture most of these overflows, channelling them to our sewage works in Beckton. There the sewage will be treated in the normal way, with renewable energy generated from the solid matter and clean water returned to the Thames.

Under the preferred delivery mechanism for the tunnel, much of the work will be carried out by a separate company, independent of Thames Water and set up specifically for the purpose, with its own licence from Ofwat.

The tunnel is part of our wider London Tideway improvements, which also include the ongoing construction of the Lee Tunnel and upgrades to the capital's five main sewage works.

Our performance targets

We have agreed with Ofwat 53 different targets for 2015-20, and will publish our performance against each of these on an annual basis.

We have also agreed financial incentives for 27 of these performance targets. This means that where we do not meet all of these targets, we will need to reduce average household bills by up to �170, spread over the period 2020-25. Where we significantly exceed these targets, we will be able to increase average household bills by up to �37, spread over the same five years. This is independent of other changes to average household bills, which include alterations in investment costs and inflation.

For illustrative purposes, we have shown four of the financial measures. Each allows you to select one of six performance levels to see the potential impact on average household bills over the period 2020-25.

The �starting point� for three of these, from which increases or decreases are measured, represents the 2014/15 performance level assumed in Ofwat�s �final determination� in December 2014.

  • �Water supply interruptions� measures the average hours lost per property served � the 2014/15 performance level assumed here was 7 minutes 48 seconds. (Please note that, for any single incident, property hours are capped at 20,000.)
  • �Leakage� shows total water lost per day.
  • �Internal sewer flooding� refers to the number of properties flooded internally, excluding those due to overloaded sewers.
  • �Pollution� refers to incidents when effluent enters a river or stream, with the potential to damage the environment.

In each case, the potential increases and decreases refer to average annual household bills. The values shown are spread across the period 2020-25, and are not annual figures.

For each of these four measures, the target we have agreed with Ofwat would put us in the top quarter of performance, compared with other water companies� current performance levels.

Other measures within the range of financial incentives include compliance with strict drinking water quality standards and the Service Incentive Mechanism, an industry-wide mechanism to encourage water companies to improve their customer service.

Please note that the figures are shown in 2014/15 prices. Payments do not affect our Customer Guarantee Scheme. More details on this, and the full range of �outcome delivery incentives�, are available on our main website.

Challenges our plan responds to

There are some big issues we face in continuing to provide high-quality water and sewerage services over the coming years - and in limiting the effect on customers' bills:

  • Affordability: Our work is ultimately paid for by all of our customers and has to remain affordable. This is a particular challenge when the state of the economy means household budgets are already under pressure. The Thames Tideway Tunnel, which is badly needed - as well as being a legal requirement - will have a significant impact on the wastewater charges paid by our customers.
  • Population growth: The population in our water supply area is likely to rise from 9 million to 10.4 million by 2040, while the population in our wastewater area is forecast to rise from 15 million to 16 million over the same period. Both will put more pressure on our pipes, treatment works and other equipment, as well as on the natural environment.
  • Climate change: The latest predictions suggest that summers will become hotter and drier, increasing the demand for water. Winters are forecast to become generally wetter, with more intense storms that will put additional pressure on our sewer network.
  • New laws and regulations: Legal changes could impose additional demands on how we operate. For example, the Water Act of 2014 is opening the water industry to greater competition, while the implementation of the EU Water Framework Directive could require stricter treatment standards at sewage works. Changes are also likely in the rules governing how water is taken from the environment.
  • Ageing equipment: Some of our equipment, although working well, is nearing the end of its life, putting it at higher risk of failure and increasing maintenance requirements. We need to make the right decisions about when and where we replace equipment.
  • Rising energy costs: Energy prices are predicted to rise steeply in the coming years. This will have a significant effect on the costs of pumping water and wastewater around our 5,000-square-mile region.
  • Customer expectations: The level of service customers expect of us is rising - a trend which is likely to continue. Technology now plays a major part in people's everyday lives. We need to keep pace with changes and offer services that match expectations.

Listening to customers

Before submitting to Ofwat the first version of our five-year plan, in December 2013, we had already sought the opinions of thousands of our customers.

As part of this, we interviewed over 5,000 people, listened to the views of more than 30,000 and received in excess of 18,000 responses to online surveys. This feedback, and the thoughts of our Customer Challenge Group, helped us put together our initial proposals.

We later, we have asked a representative sample of customers for their views on three issues:

Bills: Customers said bill increases should be smoothed from year to year, avoiding sudden rises. Our plan for 2015-2020 follows this approach as far as possible.
Our overall plan: Eight in ten customers found our plan (excluding the Thames Tideway Tunnel) reasonable. Acceptability fell to nearly six in ten when the additional Tunnel charges were included.
Incentives: Customers agreed with Ofwat's requirement for financial penalties if we don't meet certain targets, or a small increase in bills if we do. They said the most important areas to incentivise in this way were reducing supply interruptions, leakage and sewer flooding - our plan addresses these. They also said bills should be lowered if we fail certain targets - again, our plan would see bills reduced from 2020 if this happens.

Our long-term commitments

Based on what customers have told us they want, we identified six basic long-term services and benefits that we aim to provide in our five-year plan and beyond:

  • We will provide safe and reliable water that meets all necessary standards and is available when customers need it.
  • We will provide a safe and reliable wastewater service that meets all necessary standards and is available when customers need it.
  • We will show customers that they can trust us, that we are easy to do business with and that we care.
  • We will provide the services customers need in the most economic and efficient way, so that bills are no more than necessary.
  • We will limit our impact on the environment and achieve a socially responsible, sustainable business.
  • We will provide customers with a choice of easy-to-use contact options.