London Fire Brigade and Surrey Fire and Rescue Service have issued an urgent water safety warning during this week's heatwave.

On Monday, off-duty Richmond firefighter, Alastair Stewart, was spending time with his family by the river by Chertsey Meads when he prevented a boy from drowning.

His son alerted him to a teenager in trouble in the water and after helping to safely bring the boy to the bankside, Alistair used his training in immediate emergency care to carry out CPR.

He said: "I was out enjoying time with my family paddle boarding. The weather was great, and the water was very calm. Suddenly, my son starts shouting that a boy had gone under the water. I could see him near the bottom and with the help of my son managed to get him on to the paddleboard and on to the riverbank.

"I'm trained in immediate emergency care as part of my role as a firefighter and started to carry out CPR. Two doctors who happened to be nearby also came to help and an ambulance arrived.

"I was so relieved to later hear he was going to be okay, but he was also incredibly lucky. With the weather this week staying really warm and the water looking really tempting I want to help ensure people know how to spend time around water safely.

"Use life jackets when taking part in water sports and don't jump into the water. It's colder than it looks."

This incident comes after the Bridgade carried out work earlier this summer urging parents to talk to their children about the dangers of jumping into open water following the tragic death of 14-year-old Brian Sasu in Richmond last year.

Firefighters held a water safety event in Teddington alongside partners, teaching people how to use throwlines to save lives and giving water safety advice.

The Brigade also wrote to all London councils asking them to take action and carry out risk assessments to ensure waterways in their boroughs have appropriate water safety measures in place.

The letter has received response from some councils who are meeting with the Brigade's Water Safety Team to discuss how water safety can be improved in their boroughs.

London Fire Brigade's Assistant Commissioner for Prevention and Protection, Charlie Pugsley, said: "We're still sadly seeing too many incidents like this. Thanks to Firefighter Stewart's bravery, a tragedy was thankfully avoided here, but it's important to be aware of just how easy it is to get into difficulty in the water.

"Even with temperatures reaching 30 degrees this week, the water temperature can cause cold water shock. Cold water can cause your body to go into shock no matter how fit you are or well you can swim, causing panic, anxiety, disorientation, and loss of muscular control. These reactions can also cause you to gasp for air resulting in water being inhaled. If you fall into water float to live – stay calm, float on your back, and call for help.

"If you see someone in trouble in the water call 999, tell them to float on their back and throw them something that floats."

For more tips on water safety follow London Fire Brigade's water safety guide.