South West Water wasn’t singled out in the recent press reports on the shortcomings of the water companies. The reason seems to be that, in absolute terms, its leakage rate of around 127 million litres a day is not as large as say Severn Trent or United Utilities (both more than 400 million litres a day), but its performance is bad.

Owl thinks a more useful measure for comparative purposes would be percentage loss through leakage of water supplied. Unfortunately this is not a metric easily discoverable. The latest South West Water Summary Performance Report 2021 only records losses but nothing about how much water was supplied in total.

To get an estimate of water supply Owl has had to turn to South West Water’s Fact Sheet.

This states:

“We deliver over 340 million litres of water each day through some 15,000km of water mains to 800,000 homes and 70,000 businesses in the South West. About 95% of the water we supply is returned to us for treatment and disposal. We do this through some 14,995km of sewers, around 800 sewage pumping stations and over 600 treatment works, many of which serve a population of less than 1,000 people.”

How should we interpret this delivery figure?

Is this the volume of water that leaves the treatment plants and enters the delivery system?

Or is it the water estimated to have been delivered to customers’ taps after leakage? 

I.e. Is it the measure of input or output?

The Performance Report records that for 2020/21 leakage average was 126.8 million litres a day against a target of 120.5 for which South West Water received a penalty of £3.875m.

The 127 million litres per day leakage represents 37% of the total under the first interpretation and 27% of the (340+127=467) million litres a day under the second. 

Either way the leakage is colossal. Who is to blame?

What they say is:

“The network was challenged throughout the year with increased demand due to changes in customer behaviour during the multiple lockdown periods and a higher than normal regional population given the significant proportion of second home ownership in our region.

As a result, increased pumping has been required to more rural areas. There was a record number of bursts in early 2021 and our teams responded well to this increase, however as a consequence of these factors, leakage rose resulting in our three year average leakage target not being met.”

“Unfortunately, we are below the industry average for our leakage performance this year.“