The first event of the six-meeting interclub series concentrated on the distance races.
Williams (15), a pupil at St Hildas Collegiate, broke her own girls under-16 short-course record by 20.63sec in 17min 02.35sec.
This swim missed the New Zealand age-group record by 3sec and is the 38th fastest 1500m freestyle time in her age-group since September last year.
An impressive feature of William's swim was that her rating started at 44.5 strokes a minute over the first few laps and increased to 48.5 strokes in the final lap.
The national record was swum by Athens Olympian Rebecca Linton in 2001.
Stefannie Gillespie (13), a pupil at St Hildas, broke her own Otago record set in July last year by 48sec when she clocked 18min 33.30sec.
Adam Simpson (15), a pupil at Otago Boys High School, captured the a 1993 record of former international Karl Purdie-Smith in 16min 09.97sec.
It reduced his own personal-best time by 21.97sec and was 0.83sec faster than Purdie-Smith's time.
Simpson had broken Purdie-Smith's 800m freestyle time at the Neptune Carnival at Queens Birthday Weekend.
The winter series is sponsored by Absolute Insurance, which has set up a club grant system.
Waves is one of seven clubs in New Zealand to receive a grant and it uses it to run the six-meet series and develop an athlete sports science fund.
