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?
In October, we experienced above average rainfall in the Thames Catchment. At 169.6 mm, it was 227.6% of the long-term average.
Check out our graph to see rainfall difference from average for the Thames Catchment:
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 mostly average across the Thames region by the end of October. 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
By the end of October 2020, river flows in the River Thames and River Lee were average. With the significant rainfall at the beginning of October, flows increased to above average for the time of year.
Flows in the smaller rivers across the Thames region were generally average for the time of year, only Bibury Springs remained below its constraint and the Kennet at Knighton below its Abstraction Incentive Mechanism (AIM) constraint at the end of October. The AIM is an Ofwat scheme to reduce the abstraction from sources that are considered environmentally sensitive.
The Teddington Target Flow (TTF) was 800 Ml/d at the end of October. 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 October 2020:
- Reservoirs in London were 78% full (77% full in West London and 85% full in Lee Valley), which is average for the time of year.
- Farmoor Reservoir in Oxfordshire was 97% full, which is average for the time of year.
Our water resources situation
Check out our infographic to see our water resource situation at the end of October.
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.
