The new rules mean companies are required to block annual bonuses and other awards to directors where they do not comply with the watchdog’s rules.
This includes pollution incidents, poor environmental practices and criminal convictions.
Ofwat said that a further £2.4m of performance-related executive pay was not required to be blocked, but should not be funded by customers.
Among the firms that triggered its rules, Thames Water had seven of the most serious category of pollution incidents, recorded in 2024.
It also breached its licence to hold a sufficient credit rating and had a one-star rating in relation to its environmental performance.
This meant that no bonuses or other awards were paid to its chief executive or its former finance chief, who left in March.