Adam Warner successfully defended his 1,500m title at the London Region Championships.
Warner, who will represent Team GB in his first Maccabiah Games in July, also won the 400m freestyle race.
He said: "I'm really pleased with how I swam at the weekend. I hope my good times will put me in a fast heat for the Maccabiah.
"Training has been going very well and I am completing my final preparations before heading to Israel."
Warner has been acclimatising for the Games with a warm weather training camp in Mallorca. He will compete in races in Sheffield and Plymouth, as well as an open water event in Germany, before travelling to Israel.