EVENT 421 Men 1500m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 1 | Oscar Gavelle | 14 | Rotherham Mo | 18:02.15 |
| 2 | 3 | Dilanas Satavicius | 13 | Nuneaton | 17:58.82 |
| 3 | 5 | Samuel Green | 13 | Bassetlaw SS | 17:56.42 |
| 4 | 7 | Thomas Croke | 14 | Barnet Copt | 17:50.19 |
| 5 | 6 | Jack Keers | 14 | Teddington | 17:52.28 |
| 6 | 4 | Lucas Lovell | 14 | Portsmouth N | 17:57.59 |
| 7 | 2 | Eddie Evans | 14 | Beckenham | 17:59.35 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 9 | Charley King | 15 | Thanet Swim | 17:44.43 |
| 1 | 11 | Oscar Winterburn | 15 | teamipswich | 17:40.79 |
| 2 | 13 | Alfie Charlton | 15 | Harrogate | 17:38.94 |
| 3 | 15 | Ethan Wills | 15 | Wycombe Dist | 17:36.88 |
| 4 | 17 | Reuben Thomas | 14 | Mt Kelly | 17:35.72 |
| 5 | 16 | Zachary Powell | 15 | AST Burnham | 17:35.74 |
| 6 | 14 | Rufus Parry | 15 | Wycombe Dist | 17:37.25 |
| 7 | 12 | Matthew Sawers | 14 | Wigan BEST | 17:40.05 |
| 8 | 10 | Thomas Swales | 14 | Nova Cent'n | 17:43.02 |
| 9 | 8 | Euan Flannery | 14 | Warrington W | 17:49.18 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 19 | Joseph Mulligan | 17 | Nova Cent'n | 17:34.42 |
| 1 | 21 | Jacob Pillinger | 17 | Bicester | 17:34.02 |
| 2 | 23 | Ben Gilchrist | 22 | RichmondDale | 17:32.74 |
| 3 | 25 | Jack Pritchard | 16 | Wigan BEST | 17:31.53 |
| 4 | 27 | Alfie Bisby | 16 | South Lincs | 17:30.96 |
| 5 | 26 | William Hicklin | 14 | Co Leeds | 17:30.99 |
| 6 | 24 | Finlay Richardson | 14 | Guildford Ct | 17:32.67 |
| 7 | 22 | Oliver Lawson | 15 | Portsmouth N | 17:33.40 |
| 8 | 20 | Jackson Jardine | 16 | Cockermouth | 17:34.32 |
| 9 | 18 | Eamonn Djeridi | 15 | Royal Wolv | 17:34.64 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 29 | Josh Miles | 15 | Soundwell | 17:30.10 |
| 1 | 31 | Hugh Mason-Williams | 15 | Co Birm'ham | 17:29.61 |
| 2 | 33 | George Turner | 16 | Newcastle | 17:27.17 |
| 3 | 35 | Timothy Jones | 15 | Newquay | 17:26.73 |
| 4 | 37 | Daniel Payton | 14 | N & D PP SC | 17:26.49 |
| 5 | 36 | Sonny Thomas | 17 | Leander | 17:26.72 |
| 6 | 34 | Jad Idris | 17 | Co Leeds | 17:26.85 |
| 7 | 32 | Orlando Dearing | 15 | Co Peterboro | 17:28.57 |
| 8 | 30 | Alan Parra-Manzo | 16 | Maidenhead | 17:29.80 |
| 9 | 28 | Daniel Menzer | 20 | Birm'ham Uni | 17:30.49 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 39 | Makar Yakhno | 13 | Portsmouth N | 17:25.38 |
| 1 | 41 | Oscar Bellinger | 15 | Salisbury | 17:25.00 |
| 2 | 43 | Anton Supov | 16 | Maidenhead | 17:23.50 |
| 3 | 45 | Daniel Harris | 16 | Co Leicester | 17:22.81 |
| 4 | 47 | Damien Batchelor | 16 | Co Birm'ham | 17:21.50 |
| 5 | 46 | George Hooper | 16 | Co St Albans | 17:22.24 |
| 6 | 44 | Oliver Etheridge | 20 | Atlantis | 17:22.99 |
| 7 | 42 | Yassin Selmani | 15 | Barnet Copt | 17:24.36 |
| 8 | 40 | Nathan Chapman | 19 | Mt Kelly | 17:25.20 |
| 9 | 38 | Ted Whitwam | 17 | Bracknell | 17:25.64 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 49 | Lewis Jarrett | 17 | Romford Town | 17:20.89 |
| 1 | 51 | Jack Finnie | 16 | Rotherham Mo | 17:20.09 |
| 2 | 53 | Ashton Hallows | 17 | Plymouth Lea | 17:18.79 |
| 3 | 55 | Barnaby Ryder | 16 | Mt Kelly | 17:14.98 |
| 4 | 57 | Ryan Wall | 16 | Co Cambridge | 17:13.31 |
| 5 | 56 | Danielius Tuma | 19 | Crawley | 17:14.70 |
| 6 | 54 | Kenechukwu Harris-Eze | 16 | Barnet Copt | 17:16.53 |
| 7 | 52 | Jake Chesworth | 16 | Maxwell | 17:19.32 |
| 8 | 50 | Sebastian Parkes | 17 | TigersJersey | 17:20.25 |
| 9 | 48 | Daniel Pollard | 18 | KingstonHull | 17:21.11 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 0 | 59 | Daniel Jackson | 17 | Bo Kirklees | 17:11.95 |
| 1 | 61 | Daniel Moyses | 17 | Co Peterboro | 17:11.02 |
| 2 | 63 | Joshua Robinson | 18 | N & D PP SC | 17:08.61 |
| 3 | 65 | Joe Ritson | 18 | Wrekin SC | 17:00.40 |
| 4 | 67 | Will Sellars | 17 | Cayman | 16:47.15 |
| 5 | 66 | Nathan Potter | 18 | Maidenhead | 16:58.15 |
| 6 | 64 | Billy Bainbridge | 17 | Teddington | 17:07.37 |
| 7 | 62 | Amos Starkey | 18 | Gloucester | 17:10.87 |
| 8 | 60 | Benjamin Mould | 18 | Wycombe Dist | 17:11.13 |
| 9 | 58 | George Lambert | 18 | Portsmouth N | 17:13.08 |