Is Drainage Infrastructure Keeping Up With Increased Rainfall?

First of all, we must look at how rainfall has changed over the past years. The Met Office publishes seasonal and annual climate summaries which include statistics of rainfall.

Upon looking at the annual rainfall amount for 2020 (see figure 1) it shows that rainfall in parts of Dorset, specifcally Swanage, have seen up to 125% of the 1981-2010 average rainfall amount.

Figure 1 | Credit - Met Office

Last year was the UK's wettest year since 2000, with 116% of the 1981-2010 average and 122% of the 1961-1990 average rainfall.

During heavy rainfall, the capacity of the pipes that make up our combined sewage system can be exceeded, which could cause floods if not spilled out. This is why combined sewer overflows (CSOs), also known as storm drain overflows, were developed.

Wessex Water emptied CSOs 28,994 times during 2020, and this number is expected to increase if rainfall continues to rise, since CSOs must be emptied more frequently to meet demand.

"Imagine you're running a bath and it's about to overflow, what would you do? you'd turn off the tap. we can't turn off the tap."

In this clip, Ruth Barden, Director of Environmental Solutions for the company, explains why CSOs may operate more frequently and how the number of discharges could be reduced.

As rainfall is on the rise and more houses continue to be built, we would expect infrastructure of the sewer to be improved and expanded to combat the increase. However, this is dependent on local authorities.

In this clip, I ask Ruth if the sewer and rainfall infrastructure is being built to compensate for the amount of houses being built in addition to if public pressure on housing developers is enough to enforce sustainable solutions.

What do you think?

What more could local authorities and housing developers do to keep up with rainfall increases? Leave your thoughts below in the comments.