Water availability



Where our water comes from

See below the journey that water takes to get to your tap.

Stage 1 - Rain



Evaporated water in the air condenses and form clouds in the sky. When it becomes too heavy, it falls as rain.

Stage 2 - Rivers



When rain falls to the ground it flows into drains or across the ground and eventually makes its way into rivers and streams.

Stage 3 - Evaporation



The sun heats water in the oceans, rivers and lakes and it turns to water vapour. The vapour is so light that it rises.

Stage 4 - Aquifer


Chalk Aquifer

The rain that does not flow into rivers or into the sea seeps slowly through the soil and rocks into the aquifer deep underground in the rock.

Stage 5 - Water Pumping Station


Water Pumping Station

Water is pumped out of the aquifer deep underground and it is treated ready to be sent to homes and businesses.

Stage 6 - Water Distribution


Water Distribution Pipes

The pumping stations pump treated water into distribution pipes so that it reaches your taps in a clean and safe way.

Stage 7 - Your House


Your House

Now you can use the water for cleaning, cooking, drinking - to name a few uses!

View our
Water Efficiency House

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Environmental monitoring

Our Water Strategy Team undertakes routine environmental monitoring such as measuring groundwater levels and spot gauging river flows. This helps us understand the impacts of our abstractions on the local environment. In addition, we also record rainfall at strategic sites to help us understand how the weather affects our abstractions and water availability.

The monitoring that is carried out helps us to write our Water Resources Management Plan and Drought Management Plan, which allows us to plan for the future, including the best management of resources in the event of drought. For the plans in your area please click here.


River photos

As part of our routine environmental monitoring we take river photos at fixed locations every three months. This provides a valuable visual check of the rivers in our communities which is used to record both seasonal and annual changes. We have records going back more than 15 years.


River Colne - Location A


Normal flow                                                                                      High flow conditions


Low flow conditions


Recording rainfall data

We collect rainfall data on a monthly basis at some of our sites. This data is used to help us to understand the amount of rainfall which ends up back in the rivers and recharges groundwater sources. Once the data is collected and analysed, it is sent to the MET Office for their records.

Other organisations and independent recorders in the UK also contribute their observations to the MET Office. This is then collated into reports based on geographical areas.

For the latest water situation report for your area please click here .


Measuring groundwater levels

We review groundwater levels weekly using our own data and data from the Environment Agency (EA). We also record groundwater levels using data loggers for specific projects.

Between 2012 and 2015 we investigated the impacts of our abstractions on a number of local rivers, including the Colne and Ver, as part of our obligations under the National Environment Programme (NEP).

As well as assessing the impacts of our abstractions, we also explored various options of reducing or mitigating these impacts including reducing the demand for water through our Water Saving Programme, importing water from neighbouring water companies and undertaking river enhancements to help improve the ecology.

For the latest water situation report for your area please click here.


Measuring river flows

The flow in any river is constantly changing as a result of a number of factors. To monitor these changes we use a number of different tools and techniques. This includes utilising data from the Environment Agency’s (EA) automated gauging station network. We also manually spot gauge a river with the use of a flow meter. This data is collected and analysed on a regular basis and helps us understand how much water is flowing through the rivers at a set location.

For the latest water situation report for your area please click here.



Colne Community

The River Colne rises in Colney Heath and flows southwest through rural areas before entering the urban area of Watford. The Upper Colne catchment is described as having a complex groundwater and surface water flow regime and there is connectivity in the central Colne Valley through swallow holes (connecting surface water to groundwater) and varying lithology. We have carried out field investigations and monitoring to assess the impact of our abstractions on flow and ecology.


Mid Colne Abstraction Study

This study area looked at eight kilometres of the River Colne between Rickmansworth and Denham Green which included the Mid Colne Lakes, a series of 18 lakes formed as a result of historic gravel extraction. Part of the area is designated as a Site of Special Scientific Interest (SSSI). We monitored groundwater levels, river flows, lake levels and undertook ecological surveys.



Dour Community

Little Stour National Environment Programme

We are carrying out a programme of works to improve the ecological conditions of the Little Stour River with the support of other stakeholders. A steering group has been formed, with the Environment Agency (EA), to work together on this project.

An options appraisal was undertaken to identify the most beneficial schemes to improve the ecology in the river.

A number of river restoration and habitat enhancement works have been identified along the river to restore the ecological potential. A Catchment Sensitive Farming Officer will also work in the catchment, to work with farmers, landowners and agronomists to reduce the likely runoff from fields adjacent to the Little Stour and to improve the water quality in the river.


Lee Community

River Beane habitat enhancement 



The River Beane is a chalk stream tributary of the River Lea. For the section of the River Beane that flows near Watton-at-Stone, it is very over-shaded which results in a lack of marginal vegetation, due to the reduced amount of light reaching the river channel. An old weir along the river had prevented fish from moving up and down the river. This site is also in a catchment where we will be reducing abstraction to help improve flows (see sustainability reductions section).


Our involvement

We are undertaking environmental improvements in areas under stress in this river until 2020. The habitat enhancement work includes the thinning of trees that are over-shading the river, to allow more light and help aquatic plants to grow. A number of large fallen trees which are completely blocking the river will be removed and large woody material from the tree thinning will be fixed into the banks to create refuge areas for small fry, creating additional habitats for aquatic insects.

The residents in the area intend to carry out some marginal planting, using native species once the trees have been thinned. Removal of the top of the small weir has allowed fish to move up through this reach and make use of the new habitat created as a result of the enhancement work.


Over-shaded river                                                                                                 Small weir 




Misbourne Community

Misbourne River flow investigation

The River Misbourne runs for 28 km through the Chiltern Hills from its source at Mobwell Pond in Great Missenden to the River Colne at Denham. It is flanked by locally and nationally important sites and throughout its course it has varied and valuable habitats. Previous studies concluded that abstractions in the upper catchment were lowering the groundwater table and water levels in Great Missenden Abbey Park lakes. We reduced our abstractions by eight million litres per day in the 1990’s to help improve flows, but there were further concerns raised about effects on the conservation and amenity value of the river. An options appraisal was included in our Asset Management Period programme (AMP5 2010-2015) to look at further improving flow and ecology.



The River Misbourne at Bottom House Farm Lane                        The River Misbourne at Stone Cottage High Street


Shardeloes Lake which the river Misbourne flows into and out of.


Following the options appraisal, we included a further sustainability reduction for the Misbourne (See Sustainability Reduction section) along with river restoration and habitat enhancement to help achieve Good Ecological Status.




Stort Community

River Rib study


The River Rib is predominantly a groundwater-fed chalk stream characterised by narrow, steep sided shallow channels with a history of low flows during dry summer months. We investigated a 12.3km length of the river and three of our groundwater sources, to assess any impact on the flow and ecology. We undertook monitoring of groundwater levels and river flows, and carried out ecological surveys, to identify any links between our abstractions and river flows.



Upstream River Rib at Hamels Mill                                               Downstream River Rib at Hamels Mill


Upstream River Rib at Standon Village                                        Downstream River Rib at Barwich Ford