| Event | Time | Meet | Date |
|---|---|---|---|
| 100m Backstroke | 1:18.15 | 2026 Ontario Age Groups - MPAC | 2026-03-05 |
| 100m Backstroke | 1:19.26 | LAC - 12 & Under Celebration | 2026-01-17 |
| 100m Breaststroke | 1:31.95 | 2026 Ontario Age Groups - MPAC | 2026-03-05 |
| 100m Breaststroke | 1:29.11 | LAC - 12 & Under Celebration | 2026-01-17 |
| 100m Butterfly | 1:25.45 | LAC - Nothers Fall Invitational | 2025-11-21 |
| 100m Freestyle | 1:14.73 | Western Region Long Course Championships | 2025-06-13 |
| 100m Freestyle | 1:12.68 | LAC - Nothers Fall Invitational | 2025-11-21 |
| 100m IM | 1:25.76 | LAC - Fall Start Up | 2025-10-19 |
| 200m Backstroke | 2:49.57 | 2026 Ontario Age Groups - MPAC | 2026-03-05 |
| 200m Backstroke | 2:50.82 | Western Region Short Course Championships | 2026-02-12 |
| 200m Breaststroke | 3:08.34 | LC Winter Invitational | 2026-01-30 |
| 200m Breaststroke | 3:16.15 | LAC – November Fall Time Trial | 2025-11-01 |
| 200m Butterfly | 3:18.28 | LAC - Dr. Paul Hauch Invitational | 2025-07-05 |
| 200m Freestyle | 2:35.33 | Western Region Short Course Championships | 2026-02-12 |
| 200m IM | 2:56.59 | LC Winter Invitational | 2026-01-30 |
| 200m IM | 2:50.08 | Western Region Short Course Championships | 2026-02-12 |
| 400m Freestyle | 5:30.68 | LC Winter Invitational | 2026-01-30 |
| 400m Freestyle | 5:24.43 | BAC Team Showdown 2025 | 2025-12-12 |
| 400m IM | 5:59.90 | BAC Team Showdown 2025 | 2025-12-12 |
| 50m Backstroke | 36.41 | 2026 Ontario Age Groups - MPAC | 2026-03-05 |
| 50m Backstroke | 36.66 | LAC - 12 & Under Celebration | 2026-01-17 |
| 50m Breaststroke | 41.77 | 2026 Ontario Age Groups - MPAC | 2026-03-05 |
| 50m Breaststroke | 42.39 | LAC - Fall Start Up | 2025-10-19 |
| 50m Butterfly | 38.89 | Western Region Long Course Championships | 2025-06-13 |
| 50m Butterfly | 36.70 | Western Region Short Course Championships | 2026-02-12 |
| 50m Freestyle | 32.86 | BAC Team Showdown 2025 | 2025-12-12 |
| 800m Freestyle | 11:26.98 | LAC - Nothers Fall Invitational | 2025-11-21 |
Haase, William's top personal bests include 100m Backstroke (1:18.15), 100m Backstroke (1:19.26), 100m Breaststroke (1:31.95), 100m Breaststroke (1:29.11), 100m Butterfly (1:25.45).
Haase, William swims for London Aquatic Club.
Haase, William has competed in 10 meets.