There has been a recent change to the Health and Safety Executive guidance, Managing health and safety in swimming pools - HSG179.

Following research conducted by RLSS UK, which prompted some changes to the National Pool Lifeguard Qualification (NPLQ) in July 2023, the mention of 10:20 has recently been removed from HSG179. Read the latest version of the publication ‘Managing health and safety in swimming pools’ here. 
The results from the research (find out more about the research here) demonstrated that lifeguards could not follow the 10-second scanning rule despite being told to and reverted to a natural scan pattern. This prompted RLSS UK to remove 10:20 from the NPLQ in July 2023 and replace it with Natural Scan: 20. Instructing lifeguards to continuously scan the pool and/or zone they are responsible for and instructing operators to ensure lifeguards can get to any area within their zone within 20 seconds.
In July 2023, the Health and Safety Executive provided a quote supporting the changes RLSS UK had made, and now they have updated their guidance for swimming pool operators to remove 10:20.
Jo Talbot, Director RLSS UK: “I am thrilled the HSE has made the changes, and the guidance within HSG179 regarding lifeguard scanning reflects the research conducted. We pride ourselves at RLSS UK on supporting the swimming pool industry and providing the most robust qualifications to provide the best lifeguards, fully equipped to make swimming pools as safe as possible. This change means the guidance and our qualifications are in line, and most importantly, the swimming pool can ensure their lifeguards are using tried and tested methods to supervise the swimming pool, helping everyone to enjoy water safely.”
We have created a comparison between HSG179 Fourth edition 02/18 and 03/18, it details the changes relating to 10:20 and other changes that the Health and Safety Executive have made. View comparison here.