When the finale to the season takes place at Guildford in January, they will need just a point from remaining matches against closest rivals City of Manchester and City of Coventry to be sure of success.
Fiona McCann (3), Katie Hesketh (3) and Laura Hesketh (2) were the leading scorers in the win over Otter, who conceded five goals in the last quarter. Manchester won again - 15-5 against Sheffield Sharks, including five goals from Isobel Howe and four from Rosie Huck.
Otter Lutra and Leeds Sharks lead Championship 1 with 100 per cent records from four matches.