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Reservoir levels

Reservoir levels and rainfall figures

How much rain falls in our region?

It may feel like it rains a lot in the UK, but did you know that our capital city gets less rain each year than Rome, Istanbul and even sunny Sydney?

Check out our graph to see rainfall difference from average for the Thames Region:

Rainfall in the Thames region graph

Where our water comes from

We rely on rain to maintain groundwater levels in our region.

Groundwater is the water that soaks into our aquifers (underground layers of rock or unconsolidated materials through which water can flow and be stored). These supply up to 30% of the water we use every day across London and the Thames Valley. But that’s not all our aquifers do – they also help to keep our rivers flowing, which is where the remaining 70% of our water supply comes from.

Groundwater in the Thames region

Groundwater levels were average across the Thames region by the end of June, except in parts of the Cotswolds, where groundwater levels were below average, and South East London, where groundwater levels were above average.

Groundwater levels often respond slower to rainfall (or lack of it) than river flows providing resilience against short-sharp dry periods. Each aquifer has different properties and will respond in different ways.

River flow in the Thames region

During June 2020, river flows in the River Thames and River Lee were below average. Flows in the smaller rivers across the Thames region were generally average except in the west (Cotswolds) where flows were below average.

The Teddington Target Flow (TTF) was maintained at 800 Ml/d during June. The TTF is the minimum River Thames flow over the Teddington weir that is required to balance environmental, navigational and water supply needs. The TTF depends on the time of year and our reservoir storage and is always agreed with the Environment Agency.

Saving for a rainy day

We store water in large, open raw water reservoirs before we pump it to our world-class treatment plants, ready for cleaning.

We carefully monitor water levels in reservoirs, regularly inspecting and maintaining the infrastructure to safeguard your supply.

At the end of June 2020:

  • Reservoirs in London were 93% full (94% full in West London and 89% full in Lee Valley)
  • Farmoor Reservoir in Oxfordshire was 97% full

Our water resources situation

Check out our infographic to see our water resource situation at the end of June.

Water resource situation diagram

Want to help save water at home?

There are lots of ways you can help save water, from turning the taps off when you're brushing your teeth, to using rainwater for your plants.

Learn more about saving water